Magick::Image Class

Contents

Introduction

Image is the primary object in Magick++ and represents a single image frame (see image design). The STL interface must be used to operate on image sequences or images (e.g. of format GIF, TIFF, MIFF, Postscript, & MNG) which are comprized of multiple image frames. Individual frames of a multi-frame image may be requested by adding array-style notation to the end of the file name (e.g. "animation.gif[3]" retrieves the fourth frame of a GIF animation. Various image manipulation operations may be applied to the image. Attributes may be set on the image to influence the operation of the manipulation operations. The Pixels class provides low-level access to image pixels. As a convenience, including <Magick++.h> is sufficient in order to use the complete Magick++ API. The Magick++ API is enclosed within the Magick namespace so you must either add the prefix " Magick:: " to each class/enumeration name or add the statement " using namespace Magick;" after including the Magick++.h header.

The InitializeMagick() function MUST be invoked before constructing any Magick++ objects. This used to be optional, but now it is absolutely required. This function initalizes semaphores and configuration information necessary for the software to work correctly. Failing to invoke InitializeMagick() is likely to lead to a program crash or thrown assertion. If the program resides in the same directory as the GraphicsMagick files, then argv[0] may be passed as an argument so that GraphicsMagick knows where its files reside, otherwise NULL may be passed and GraphicsMagick will try to use other means (if necessary).

The preferred way to allocate Image objects is via automatic allocation (on the stack). There is no concern that allocating Image objects on the stack will excessively enlarge the stack since Magick++ allocates all large data objects (such as the actual image data) from the heap. Use of automatic allocation is preferred over explicit allocation (via new) since it is much less error prone and allows use of C++ scoping rules to avoid memory leaks. Use of automatic allocation allows Magick++ objects to be assigned and copied just like the C++ intrinsic data types (e.g. 'int '), leading to clear and easy to read code. Use of automatic allocation leads to naturally exception-safe code since if an exception is thrown, the object is automatically deallocated once the stack unwinds past the scope of the allocation (not the case for objects allocated via new ).

Image is very easy to use. For example, here is a the source to a program which reads an image, crops it, and writes it to a new file (the exception handling is optional but strongly recommended):

#include <Magick++.h>
#include <iostream>
using namespace std;
using namespace Magick;
int main(int argc,char **argv)
{
  InitializeMagick(*argv);

  // Construct the image object. Seperating image construction from the
  // the read operation ensures that a failure to read the image file
  // doesn't render the image object useless.
  Image image;

  try {
    // Read a file into image object
    image.read( "girl.gif" );

    // Crop the image to specified size (width, height, xOffset, yOffset)
    image.crop( Geometry(100,100, 100, 100) );

    // Write the image to a file
    image.write( "x.gif" );
  }
  catch( Exception &error_ )
    {
      cout << "Caught exception: " << error_.what() << endl;
      return 1;
    }
  return 0;
}

The following is the source to a program which illustrates the use of Magick++'s efficient reference-counted assignment and copy-constructor operations which minimize use of memory and eliminate unncessary copy operations (allowing Image objects to be efficiently assigned, and copied into containers). The program accomplishes the following:

  1. Read master image.
  2. Assign master image to second image.
  3. Zoom second image to the size 640x480.
  4. Assign master image to a third image.
  5. Zoom third image to the size 800x600.
  6. Write the second image to a file.
  7. Write the third image to a file.
#include <Magick++.h>
#include <iostream>
using namespace std;
using namespace Magick;
int main(int argc,char **argv)
{
    InitializeMagick(*argv);
    Image master("horse.jpg");
    Image second = master;
    second.zoom("640x480");
    Image third = master;
    third.zoom("800x600");
    second.write("horse640x480.jpg");
    third.write("horse800x600.jpg");
    return 0;
}

During the entire operation, a maximum of three images exist in memory and the image data is never copied.

The following is the source for another simple program which creates a 100 by 100 pixel white image with a red pixel in the center and writes it to a file:

#include <Magick++.h>
using namespace std;
using namespace Magick;
int main(int argc,char **argv)
{
    InitializeMagick(*argv);
    Image image( "100x100", "white" );
    image.pixelColor( 49, 49, "red" );
    image.write( "red_pixel.png" );
    return 0;
}

If you wanted to change the color image to grayscale, you could add the lines:

image.quantizeColorSpace( GRAYColorspace );
image.quantizeColors( 256 );
image.quantize( );

or, more simply:

image.type( GrayscaleType );

prior to writing the image.

BLOBs

While encoded images (e.g. JPEG) are most often written-to and read-from a disk file, encoded images may also reside in memory. Encoded images in memory are known as BLOBs (Binary Large OBjects) and may be represented using the Blob class. The encoded image may be initially placed in memory by reading it directly from a file, reading the image from a database, memory-mapped from a disk file, or could be written to memory by Magick++. Once the encoded image has been placed within a Blob, it may be read into a Magick++ Image via a constructor or read() . Likewise, a Magick++ image may be written to a Blob via write().

An example of using Image to write to a Blob follows:

#include <Magick++.h>
using namespace std;
using namespace Magick;
int main(int argc,char **argv)
{
    // Read GIF file from disk
    Image image( "giraffe.gif" );

    // Write to BLOB in JPEG format
    Blob blob;
    image.magick( "JPEG" ) // Set JPEG output format
    image.write( &blob );

    [ Use BLOB data (in JPEG format) here ]

    return 0;
}

likewise, to read an image from a Blob, you could use one of the following examples:

[ Entry condition for the following examples is that data is pointer to encoded image data and length represents the size of the data ]

Blob blob( data, length );
Image image( blob );

or

Blob blob( data, length );
Image image;
image.read( blob);

Some images do not contain their size or format so the size and format must be specified in advance:

Blob blob( data, length );
Image image;
image.size( "640x480")
image.magick( "RGBA" );
image.read( blob);

Construct An Image

An Image may be constructed in a number of ways. It may be constructed from a file, a URL, or an encoded image (e.g. JPEG) contained in an in-memory Blob . The following Image constructors and assignment operators are available:

Construct from image file or image specification:

Image( const std::string &imageSpec_ )

Construct a blank image canvas of specified size and color:

Image( const Geometry &size_, const Color &color_ )

Construct Image from in-memory Blob:

Image ( const Blob &blob_ )

Construct Image of specified size from in-memory Blob:

Image ( const Blob &blob_, const Geometry &size_ )

Construct Image of specified size and depth from in-memory Blob:

Image ( const Blob &blob_, const Geometry &size,
        const unsigned int depth )

Construct Image of specified size, depth, and format from in-memory Blob:

Image ( const Blob &blob_, const Geometry &size,
        const unsigned int depth_,
        const std::string &magick_ )

Construct Image of specified size, and format from in-memory Blob:

Image ( const Blob &blob_, const Geometry &size,
        const std::string &magick_ )

Construct an image based on an array of raw pixels, of specified type and mapping, in memory:

Image ( const unsigned int width_,
        const unsigned int height_,
        const std::string &map_,
        const StorageType type_,
        const void *pixels_ )

Default constructor:

Image( void )

Copy constructor:

Image ( const Image & image_ )

Assignment operator:

Image& operator= ( const Image &image_ )

Read Or Write An Image

ping

Ping is similar to read except only enough of the image is read to determine the image columns, rows, and filesize. Access the columns(), rows(), and fileSize() attributes after invoking ping. The image pixels are not valid after calling ping:

void            ping ( const std::string &imageSpec_ )

Ping is similar to read except only enough of the image is read to determine the image columns, rows, and filesize. Access the columns(), rows(), and fileSize() attributes after invoking ping. The image pixels are not valid after calling ping:

void            ping ( const Blob &blob_ )

read

Read single image frame into current object. Use ping instead if you want to obtain the basic attributes of the image without reading the whole file/blob:

void            read ( const std::string &imageSpec_ )

Read single image frame of specified size into current object:

void            read ( const Geometry &size_,
                       const std::string &imageSpec_ )

Read single image frame from in-memory Blob:

void            read ( const Blob        &blob_ )

Read single image frame of specified size from in-memory Blob:

void            read ( const Blob        &blob_,
                       const Geometry    &size_ )

Read single image frame of specified size and depth from in-memory Blob:

void            read ( const Blob         &blob_,
                       const Geometry     &size_,
                       const unsigned int depth_ )

Read single image frame of specified size, depth, and format from in-memory Blob:

void            read ( const Blob         &blob_,
                       const Geometry     &size_,
                       const unsigned int depth_,
                       const std::string  &magick_ )

Read single image frame of specified size, and format from in-memory Blob:

void            read ( const Blob         &blob_,
                       const Geometry     &size_,
                       const std::string  &magick_ )

Read single image frame from an array of raw pixels, with specified storage type (ConstituteImage), e.g. image.read( 640, 480, "RGB", 0, pixels ):

void            read ( const unsigned int width_,
                       const unsigned int height_,
                       const std::string &map_,
                       const StorageType  type_,
                       const void        *pixels_ )

write

Write single image frame to a file:

void            write ( const std::string &imageSpec_ )

Write single image frame to in-memory Blob, with optional format and adjoin parameters:

void            write ( Blob *blob_ )

void            write ( Blob *blob_,
                        const std::string &magick_ )

void            write ( Blob *blob_,
                        const std::string &magick_,
                        const unsigned int depth_ )

Write single image frame to an array of pixels with storage type specified by user (DispatchImage), e.g. image.write( 0, 0, 640, 1, "RGB", 0, pixels ):

void            write ( const int x_,
                        const int y_,
                        const unsigned int columns_,
                        const unsigned int rows_,
                        const std::string& map_,
                        const StorageType type_,
                        void *pixels_ )

Manipulate An Image

Image supports access to all the single-image (versus image-list) manipulation operations provided by the GraphicsMagick library. If you must process a multi-image file (such as an animation), the STL interface , which provides a multi-image abstraction on top of Image, must be used.

Image manipulation methods are very easy to use. For example:

Image image;
image.read("myImage.tiff");
image.addNoise(GaussianNoise);
image.write("myImage.tiff");

adds gaussian noise to the image file "myImage.tiff".

The following image manipulation methods are available:

adaptiveThreshold

Apply adaptive thresholding to the image (see http://homepages.inf.ed.ac.uk/rbf/HIPR2/adpthrsh.htm). Adaptive thresholding is useful if the ideal threshold level is not known in advance, or if the illumination gradient is not constant across the image. Adaptive thresholding works by evaulating the mean (average) of a pixel region (size specified by width and height) and using the mean as the thresholding value. In order to remove residual noise from the background, the threshold may be adjusted by subtracting a constant offset (default zero) from the mean to compute the threshold:

void            adaptiveThreshold ( const unsigned int width,
                                    const unsigned int height,
                                    const unsigned offset = 0 )

addNoise

Add noise to image with the specified noise type:

void            addNoise ( const NoiseType noiseType_ )

addNoiseChannel

Add noise to an image channel with the specified noise type. The channel parameter specifies the channel to add noise to. The noiseType parameter specifies the type of noise:

void            addNoiseChannel ( const ChannelType channel_,
                                  const NoiseType noiseType_)

affineTransform

Transform image by specified affine (or free transform) matrix:

void            affineTransform ( const DrawableAffine &affine )

annotate

Annotate image (draw text on image)

Gravity effects text placement in bounding area according to these rules:

NorthWestGravity
text bottom-left corner placed at top-left
NorthGravity
text bottom-center placed at top-center
NorthEastGravity
text bottom-right corner placed at top-right
WestGravity
text left-center placed at left-center
CenterGravity
text center placed at center
EastGravity
text right-center placed at right-center
SouthWestGravity
text top-left placed at bottom-left
SouthGravity
text top-center placed at bottom-center
SouthEastGravity
text top-right placed at bottom-right

Annotate using specified text, and placement location:

void            annotate ( const std::string &text_,
                           const Geometry &location_ )

Annotate using specified text, bounding area, and placement gravity:

void            annotate ( const std::string &text_,
                           const Geometry &boundingArea_,
                           const GravityType gravity_ )

Annotate with text using specified text, bounding area, placement gravity, and rotation:

void            annotate ( const std::string &text_,
                           const Geometry &boundingArea_,
                           const GravityType gravity_,
                           const double degrees_ )

Annotate with text (bounding area is entire image) and placement gravity:

void            annotate ( const std::string &text_,
                           const GravityType gravity_ )

blur

Blur an image with the specified blur factor.

The radius parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel. The sigma parameter specifies the standard deviation of the Laplacian, in pixels:

void            blur ( const double radius_ = 0.0,
                       const double sigma_ = 1.0  )

blurChannel

Blur an image channel with the specified blur factor.

The channel parameter specifies the channel to modify. The radius parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel. The sigma parameter specifies the standard deviation of the Laplacian, in pixels:

void            blurChannel ( const ChannelType channel_,
                              const double radius_ = 0.0,
                              const double sigma_ = 1.0  )

border

Border image (add border to image). The color of the border is specified by the borderColor attribute:

void            border ( const Geometry &geometry_
                         = borderGeometryDefault )

cdl

Bake in the ASC-CDL, which is a convention for the for the exchange of basic primary color grading information between for the exchange of basic primary color grading information between equipment and software from different manufacturers. It is a useful transform for other purposes as well:

void cdl ( const std::string &cdl_ )

See CdlImage for more details on the ASC-CDL.

channel

Extract channel from image. Use this option to extract a particular channel from the image. MatteChannel for example, is useful for extracting the opacity values from an image:

void            channel ( const ChannelType channel_ )

channelDepth

Set or obtain modulus channel depth:

void            channelDepth ( const ChannelType channel_,
                               const unsigned int depth_ )

unsigned int    channelDepth ( const ChannelType channel_ )

charcoal

Charcoal effect image (looks like charcoal sketch).

The radius parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel. The sigma parameter specifies the standard deviation of the Laplacian, in pixels:

void            charcoal ( const double radius_ = 0.0,
                           const double sigma_ = 1.0 )

chop

Chop image (remove vertical or horizontal subregion of image):

void            chop ( const Geometry &geometry_ )

colorize

Colorize image with pen color, using specified percent opacity for red, green, and blue quantums:

void            colorize ( const unsigned int opacityRed_,
                           const unsigned int opacityGreen_,
                           const unsigned int opacityBlue_,
                           const Color &penColor_ )

Colorize image with pen color, using specified percent opacity:

void            colorize ( const unsigned int opacity_,
                           const Color &penColor_ )

colorMatrix

Apply a color matrix to the image channels. The user supplied matrix may be of order 1 to 5 (1x1 through 5x5):

void            colorMatrix (const unsigned int order_,
                             const double *color_matrix_)

See ColorMatrixImage for more details.

comment

Comment image (add comment string to image). By default, each image is commented with its file name. Use this method to assign a specific comment to the image. Optionally you can include the image filename, type, width, height, or other image attributes by embedding special format characters:

void            comment ( const std::string &comment_ )

compare

Compare current image with another image. Sets meanErrorPerPixel, normalizedMaxError, and normalizedMeanError in the current image. False is returned if the images are identical. An ErrorOption exception is thrown if the reference image columns, rows, colorspace, or matte differ from the current image:

bool            compare ( const Image &reference_ )

composite

Compose an image onto another at specified x and y offset and using a specified algorithm:

void            composite ( const Image &compositeImage_,
                            const int xOffset_,
                            const int yOffset_,
                            const CompositeOperator compose_
                            = InCompositeOp )

void            composite ( const Image &compositeImage_,
                            const Geometry &offset_,
                            const CompositeOperator compose_
                            = InCompositeOp )

void            composite ( const Image &compositeImage_,
                            const GravityType gravity_,
                            const CompositeOperator compose_
                            = InCompositeOp )

contrast

Contrast image (enhance intensity differences in image):

void            contrast ( const unsigned int sharpen_ )

convolve

Convolve image. Applies a user-specified convolution to the image. The order parameter represents the number of columns and rows in the filter kernel while kernel is a two-dimensional array of doubles representing the convolution kernel to apply:

void            convolve ( const unsigned int order_,
                           const double *kernel_ )

crop

Crop image (return subregion of original image):

void            crop ( const Geometry &geometry_ )

cycleColormap

Cycle (rotate) image colormap:

void            cycleColormap ( const int amount_ )

despeckle

Despeckle image (reduce speckle noise):

void            despeckle ( void )

display

Display image on screen. Caution: if an image format is is not compatible with the display visual (e.g. JPEG on a colormapped display) then the original image will be altered. Use a copy of the original if this is a problem:

void display ( void )

draw

Draw shape or text on image using a single drawable object:

void            draw ( const Drawable &drawable_ );

Draw shapes or text on image using a set of Drawable objects contained in an STL list. Use of this method improves drawing performance and allows batching draw objects together in a list for repeated use:

void            draw ( const std::list<Magick::Drawable> &drawable_ );

edge

Edge image (hilight edges in image). The radius is the radius of the pixel neighborhood.. Specify a radius of zero for automatic radius selection:

void            edge ( const double radius_ = 0.0 )

emboss

Emboss image (hilight edges with 3D effect). The radius parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel. The sigma parameter specifies the standard deviation of the Laplacian, in pixels:

void            emboss ( const double radius_ = 0.0,
                         const double sigma_ = 1.0)

enhance

Enhance image (minimize noise):

void            enhance ( void );

equalize

Equalize image (histogram equalization):

void            equalize ( void )

erase

Set all image pixels to the current background color:

void            erase ( void )

flip

Flip image (reflect each scanline in the vertical direction):

void            flip ( void )

floodFillColor

Flood-fill color across pixels that match the color of the target pixel and are neighbors of the target pixel. Uses current fuzz setting when determining color match:

void            floodFillColor( const unsigned int x_,
                                const unsigned int y_,
                                const Color &fillColor_ )

void            floodFillColor( const Geometry &point_,
                                const Color &fillColor_ )

Flood-fill color across pixels starting at target-pixel and stopping at pixels matching specified border color. Uses current fuzz setting when determining color match:

void            floodFillColor( const unsigned int x_,
                                const unsigned int y_,
                                const Color &fillColor_,
                                const Color &borderColor_ )

void            floodFillColor( const Geometry &point_,
                                const Color &fillColor_,
                                const Color &borderColor_ )

floodFillOpacity

Flood-fill pixels matching color (within fuzz factor) of target pixel(x,y) with replacement opacity value using method:

void            floodFillOpacity ( const unsigned int x_,
                                   const unsigned int y_,
                                   const unsigned int opacity_,
                                   const PaintMethod method_ )

floodFillTexture

Flood-fill texture across pixels that match the color of the target pixel and are neighbors of the target pixel. Uses current fuzz setting when determining color match:

void            floodFillTexture( const unsigned int x_,
                                  const unsigned int y_,
                                  const Image &texture_ )

void            floodFillTexture( const Geometry &point_,
                                  const Image &texture_ )

Flood-fill texture across pixels starting at target-pixel and stopping at pixels matching specified border color. Uses current fuzz setting when determining color match:

void            floodFillTexture( const unsigned int x_,
                                  const unsigned int y_,
                                  const Image &texture_,
                                  const Color &borderColor_ )

void            floodFillTexture( const Geometry &point_,
                                  const Image &texture_,
                                  const Color &borderColor_ )

flop

Flop image (reflect each scanline in the horizontal direction):

void            flop ( void );

frame

Draw a decorative frame around the image:

void            frame ( const Geometry &geometry_ = frameGeometryDefault )

void            frame ( const unsigned int width_,
                        const unsigned int height_,
                        const int innerBevel_ = 6,
                        const int outerBevel_ = 6 )

gamma

Gamma correct the image or individual image channels:

void            gamma ( const double gamma_ )

void            gamma ( const double gammaRed_,
                        const double gammaGreen_,
                        const double gammaBlue_ )

gaussianBlur

Gaussian blur image. The number of neighbor pixels to be included in the convolution mask is specified by width. The standard deviation of the gaussian bell curve is specified by sigma:

void            gaussianBlur ( const double width_, const double sigma_ )

gaussianBlurChannel

Gaussian blur image channel. The number of neighbor pixels to be included in the convolution mask is specified by width. The standard deviation of the gaussian bell curve is specified by sigma:

void            gaussianBlurChannel ( const ChannelType channel_,
                                      const double width_,
                                      const double sigma_ )

implode

Implode image (special effect):

void            implode ( const double factor_ )

haldClut

Apply a color lookup table (Hald CLUT) to the image:

void            haldClut ( const Image &clutImage_ )

See HaldClutImage for more details.

label

Assign a label to an image. Use this option to assign a specific label to the image. Optionally you can include the image filename, type, width, height, or scene number in the label by embedding special format characters. If the first character of string is @, the image label is read from a file titled by the remaining characters in the string. When converting to Postscript, use this option to specify a header string to print above the image:

void            label ( const std::string &label_ )

level

Level image to increase image contrast, and/or adjust image gamma. Adjust the levels of the image by scaling the colors falling between specified white and black points to the full available quantum range. The parameters provided represent the black, mid (gamma), and white points. The black point specifies the darkest color in the image. Colors darker than the black point are set to zero. Mid point (gamma) specifies a gamma correction to apply to the image. White point specifies the lightest color in the image. Colors brighter than the white point are set to the maximum quantum value. The black and white point have the valid range 0 to MaxRGB while mid (gamma) has a useful range of 0 to ten:

void            level ( const double black_point,
                        const double white_point,
                        const double mid_point=1.0 )

levelChannel

Level image channel to increase image contrast, and/or adjust image gamma. Adjust the levels of the image channel by scaling the colors falling between specified white and black points to the full available quantum range. The parameters provided represent the black, mid (gamma), and white points. The black point specifies the darkest color in the image. Colors darker than the black point are set to zero. Mid point (gamma) specifies a gamma correction to apply to the image. White point specifies the lightest color in the image. Colors brighter than the white point are set to the maximum quantum value. The black and white point have the valid range 0 to MaxRGB while mid (gamma) has a useful range of 0 to ten:

void            levelChannel ( const ChannelType channel,
                               const double black_point,
                               const double white_point,
                               const double mid_point=1.0 )

magnify

Magnify image by integral size (double the dimensions):

void            magnify ( void )

map

Remap image colors with closest color from a reference image. Set dither to true in to apply Floyd/Steinberg error diffusion to the image. By default, color reduction chooses an optimal set of colors that best represent the original image. Alternatively, you can choose a particular set of colors from an image file with this option:

void            map ( const Image &mapImage_ ,
                      const bool dither_ = false )

matteFloodfill

Floodfill designated area with a replacement opacity value:

void            matteFloodfill ( const Color &target_ ,
                                 const unsigned int opacity_,
                                 const int x_, const int y_,
                                 const PaintMethod method_ )

medianFilter

Filter image by replacing each pixel component with the median color in a circular neighborhood:

void            medianFilter ( const double radius_ = 0.0 )

minify

Reduce image by integral (half) size:

void            minify ( void )

modifyImage

Prepare to update image (copy if reference > 1). Normally Magick++'s implicit reference counting takes care of all instance management. In the rare case that the automatic instance management does not work, use this method to assure that there is only one reference to the image to be modified. It should be used in the cases where a GraphicsMagick C function is used directly on an image which may have multiple references:

void            modifyImage ( void )

modulate

Modulate percent hue, saturation, and brightness of an image. Modulation of saturation and brightness is as a ratio of the current value (1.0 for no change). Modulation of hue is an absolute rotation of -180 degrees to +180 degrees from the current position corresponding to an argument range of 0 to 2.0 (1.0 for no change):

void            modulate ( const double brightness_,
                           const double saturation_,
                           const double hue_ )

motionBlur

Motion blur image with specified blur factor. The radius parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel. The sigma parameter specifies the standard deviation of the Laplacian, in pixels. The angle parameter specifies the angle the object appears to be comming from (zero degrees is from the right):

void            motionBlur ( const double radius_,
                             const double sigma_,
                             const double angle_ )

negate

Negate colors in image. Set grayscale to only negate grayscale values in image:

void            negate ( const bool grayscale_ = false )

normalize

Normalize image (increase contrast by normalizing the pixel values to span the full range of color values):

void            normalize ( void )

oilPaint

Oilpaint image (image looks like an oil painting):

void            oilPaint ( const double radius_ = 3.0 )

opacity

Set or attenuate the opacity channel in the image. If the image pixels are opaque then they are set to the specified opacity value, otherwise they are blended with the supplied opacity value. The value of opacity ranges from 0 (completely opaque) to MaxRGB. The defines OpaqueOpacity and TransparentOpacity are available to specify completely opaque or completely transparent, respectively:

void            opacity ( const unsigned int opacity_ )

opaque

Change color of specified opaque pixel to specified pen color:

void            opaque ( const Color &opaqueColor_,
                         const Color &penColor_ )

quantize

Quantize image (reduce number of colors). Set measureError to true in order to calculate error attributes:

void            quantize ( const bool measureError_ = false )

quantumOperator

Apply an arithmetic or bitwise operator to the image pixel quantums:

void            quantumOperator ( const ChannelType channel_,
                                  const QuantumOperator operator_,
                                  double rvalue_)

void            quantumOperator ( const int x_,const int y_,
                                  const unsigned int columns_,
                                  const unsigned int rows_,
                                  const ChannelType channel_,
                                  const QuantumOperator operator_,
                                  const double rvalue_)

process

Execute a named process module using an argc/argv syntax similar to that accepted by a C 'main' routine. An exception is thrown if the requested process module doesn't exist, fails to load, or fails during execution:

void            process ( std::string name_,
                          const int argc_,
                          char **argv_ )

raise

Raise image (lighten or darken the edges of an image to give a 3-D raised or lowered effect):

void            raise ( const Geometry &geometry_ = "6x6+0+0",
                        const bool raisedFlag_ = false )

randomThreshold

Random threshold image.

Changes the value of individual pixels based on the intensity of each pixel compared to a random threshold. The result is a low-contrast, two color image. The thresholds argument is a geometry containing LOWxHIGH thresholds. If the string contains 2x2, 3x3, or 4x4, then an ordered dither of order 2, 3, or 4 will be performed instead. If a channel argument is specified then only the specified channel is altered. This is a very fast alternative to 'quantize' based dithering:

void            randomThreshold( const Geometry &thresholds_ )

randomThresholdChannel

Random threshold image channel.

Changes the value of individual pixels based on the intensity of each pixel compared to a random threshold. The result is a low-contrast, two color image. The thresholds argument is a geometry containing LOWxHIGH thresholds. If the string contains 2x2, 3x3, or 4x4, then an ordered dither of order 2, 3, or 4 will be performed instead. If a channel argument is specified then only the specified channel is altered. This is a very fast alternative to 'quantize' based dithering:

void            randomThresholdChannel( const Geometry &thresholds_,
                                        const ChannelType channel_ )

reduceNoise

Reduce noise in image using a noise peak elimination filter:

void            reduceNoise ( void )

void            reduceNoise ( const double order_ )

roll

Roll image (rolls image vertically and horizontally) by specified number of columnms and rows):

void            roll ( const Geometry &roll_ )

void            roll ( const unsigned int columns_,
                       const unsigned int rows_ )

rotate

Rotate image counter-clockwise by specified number of degrees:

void            rotate ( const double degrees_ )

sample

Resize image by using pixel sampling algorithm:

void            sample ( const Geometry &geometry_ )

scale

Resize image by using simple ratio algorithm which provides good quality:

void            scale ( const Geometry &geometry_ )

scale

Resize image using several algorithms to make smaller images very quickly. This is very useful to create thumbnails from large images but usually works well for any image resizing purpose:

void            thumbnail ( const Geometry &geometry_ );

segment

Segment (coalesce similar image components) by analyzing the histograms of the color components and identifying units that are homogeneous with the fuzzy c-means technique. A histogram is built for the image. This histogram is filtered to reduce noise and a second derivative of the histogram plot is built and used to identify potential cluster colors (peaks in the histogram). The cluster colors are then validated by scanning through all of the pixels to see how many pixels fall within each cluster. Some candidate cluster colors may not match any of the image pixels at all and should be discarded. Specify clusterThreshold, as the number of pixels matching a cluster color in order for the cluster to be considered valid. SmoothingThreshold eliminates noise in the second derivative of the histogram. As the value is increased, you can expect a smoother second derivative. The default is 1.5:

void            segment ( const double clusterThreshold_ = 1.0,
                          const double smoothingThreshold_ = 1.5 )

shade

Shade image using distant light source. Specify azimuth and elevation as the position of the light source. By default, the shading results as a grayscale image.. Set colorShading to true to shade the red, green, and blue components of the image:

void            shade ( const double azimuth_ = 30,
                        const double elevation_ = 30,
                        const bool   colorShading_ = false )

sharpen

Sharpen pixels in image. The radius parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel. The sigma parameter specifies the standard deviation of the Laplacian, in pixels:

void            sharpen ( const double radius_ = 0.0,
                          const double sigma_ = 1.0 )

sharpenChannel

Sharpen pixels in image channel. The radius parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel. The sigma parameter specifies the standard deviation of the Laplacian, in pixels:

void            sharpenChannel ( const ChannelType channel_,
                                 const double radius_ = 0.0,
                                 const double sigma_ = 1.0 )

shave

Shave pixels from image edges:

void            shave ( const Geometry &geometry_ )

shear

Shear image (create parallelogram by sliding image by X or Y axis). Shearing slides one edge of an image along the X or Y axis, creating a parallelogram. An X direction shear slides an edge along the X axis, while a Y direction shear slides an edge along the Y axis. The amount of the shear is controlled by a shear angle. For X direction shears, x degrees is measured relative to the Y axis, and similarly, for Y direction shears y degrees is measured relative to the X axis. Empty triangles left over from shearing the image are filled with the color defined as borderColor:

void            shear ( const double xShearAngle_,
                        const double yShearAngle_ )

solarize

Solarize image (similar to effect seen when exposing a photographic film to light during the development process):

void            solarize ( const double factor_ = 50.0 )

spread

Spread pixels randomly within image by specified ammount:

void            spread ( const unsigned int amount_ = 3 )

stegano

Add a digital watermark to the image (based on second image):

void            stegano ( const Image &watermark_ )

stereo

Create an image which appears in stereo when viewed with red-blue glasses (Red image on left, blue on right):

void            stereo ( const Image &rightImage_ )

strip

Remove all profiles and text attributes from the image.

void strip ( void );

swirl

Swirl image (image pixels are rotated by degrees):

void            swirl ( const double degrees_ )

texture

Channel a texture on pixels matching image background color:

void            texture ( const Image &texture_ )

threshold

Threshold image channels (below threshold becomes black, above threshold becomes white). The range of the threshold parameter is 0 to MaxRGB:

void            threshold ( const double threshold_ )

transform

Transform image based on image and crop geometries. Crop geometry is optional:

void            transform ( const Geometry &imageGeometry_ )

void            transform ( const Geometry &imageGeometry_,
                            const Geometry &cropGeometry_  )

transparent

Add matte channel to image, setting pixels matching color to transparent:

void            transparent ( const Color &color_ )

trim

Trim edges that are the background color from the image:

void            trim ( void )

type

Convert the image representation to the specified type or retrieve the current image type. If the image is reduced to an inferior type, then image information may be lost (e.g. color changed to grayscale).

Available enumerations for the type parameter:

BilevelType
black/white
GrayscaleType
grayscale
GrayscaleMatteType
grayscale with alpha (opacity) channel
PaletteType
colormapped
PaletteMatteType
colormapped with transparency
TrueColorType
true (full) color
TrueColorMatteType
true (full) color with alpha (opacity) channel
ColorSeparationType
Cyan, magenta, yellow, and black
ColorSeparationMatteType
Cyan, magenta, yellow, and black with alpha (opacity) channel
OptimizeType
Optimize the image type to best represent the existing pixels
void            type ( const ImageType type_ )

ImageType       type ( void ) const

unsharpmask

Replace image with a sharpened version of the original image using the unsharp mask algorithm.

radius
the radius of the Gaussian, in pixels, not counting the center pixel.
sigma
the standard deviation of the Gaussian, in pixels.
amount
the percentage of the difference between the original and the blur image that is added back into the original.
threshold
the threshold in pixels needed to apply the diffence amount.
void            unsharpmask ( const double radius_,
                              const double sigma_,
                              const double amount_,
                              const double threshold_ )

unsharpmaskChannel

Replace image channel with a sharpened version of the original image using the unsharp mask algorithm.

channel
image channel to modify.
radius
the radius of the Gaussian, in pixels, not counting the center pixel.
sigma
the standard deviation of the Gaussian, in pixels.
amount
the percentage of the difference between the original and the blur image that is added back into the original.
threshold
the threshold in pixels needed to apply the diffence amount.
void            unsharpmaskChannel ( const ChannelType channel_,
                                     const double radius_,
                                     const double sigma_,
                                     const double amount_,
                                     const double threshold_ );

wave

Map image pixels to a sine wave:

void            wave ( const double amplitude_ = 25.0,
                       const double wavelength_ = 150.0 )

zoom

Zoom (resize) image to specified size:

void            zoom ( const Geometry &geometry_ )

Set/Get Image Attributes

Image attributes are set and obtained via methods in Image. Except for methods which accept pointer arguments (e.g. chromaBluePrimary) all methods return attributes by value.

Image attributes are easily used. For example, to set the resolution of the TIFF file "file.tiff" to 150 dots-per-inch (DPI) in both the horizontal and vertical directions, you can use the following example code:

string filename("file.tiff");
Image image;
image.read(filename);
image.resolutionUnits(PixelsPerInchResolution);
image.density(Geometry(150,150));   // could also use image.density("150x150")
image.write(filename)

The following image attribute methods are available:

adjoin

Join images into a single multi-image file:

void            adjoin ( const bool flag_ )

bool            adjoin ( void ) const

antiAlias

Control antialiasing of rendered Postscript and Postscript or TrueType fonts. Enabled by default:

void            antiAlias( const bool flag_ )

bool            antiAlias( void )

animationDelay

Time in 1/100ths of a second (0 to 65535) which must expire before displaying the next image in an animated sequence. This option is useful for regulating the animation of a sequence of GIF images within Netscape:

void            animationDelay ( const unsigned int delay_ )

unsigned int    animationDelay ( void ) const

animationIterations

Number of iterations to loop an animation (e.g. Netscape loop extension) for:

void            animationIterations ( const unsigned int iterations_ )

unsigned int    animationIterations ( void ) const

attribute

Access an arbitrary named image attribute. Any number of named attributes may be attached to the image. For example, the image comment is a named image attribute with the name "comment". EXIF tags are attached to the image as named attributes. Use the syntax "EXIF:<tag>" to request an EXIF tag similar to "EXIF:DateTime":

void            attribute ( const std::string name_,
                            const std::string value_ )

std::string     attribute ( const std::string name_ )

backgroundColor

Image background color:

void            backgroundColor ( const Color &color_ )

Color           backgroundColor ( void ) const

backgroundTexture

Image file name to use as the background texture. Does not modify image pixels:

void            backgroundTexture (const std::string &backgroundTexture_ )

std::string     backgroundTexture ( void ) const

baseColumns

Base image width (before transformations):

unsigned int    baseColumns ( void ) const

baseFilename

Base image filename (before transformations):

std::string     baseFilename ( void ) const

baseRows

Base image height (before transformations):

unsigned int    baseRows ( void ) const

borderColor

Image border color:

void            borderColor ( const Color &color_ )

Color           borderColor ( void ) const

boundingBox

Return smallest bounding box enclosing non-border pixels. The current fuzz value is used when discriminating between pixels. This is the crop bounding box used by crop(Geometry(0,0)):

Geometry        boundingBox ( void ) const

boxColor

Base color that annotation text is rendered on (default none):

void            boxColor ( const Color &boxColor_ )

Color           boxColor ( void ) const

cacheThreshold

Pixel cache threshold in megabytes. Once this memory threshold is exceeded, all subsequent pixels cache operations are to/from disk. This setting is shared by all Image objects:

static void     cacheThreshold ( const unsigned int threshold_ )

chromaBluePrimary

Chromaticity blue primary point (e.g. x=0.15, y=0.06):

void            chromaBluePrimary ( const double x_, const double y_ )

void            chromaBluePrimary ( double *x_, double *y_ ) const

chromaGreenPrimary

Chromaticity green primary point (e.g. x=0.3, y=0.6):

void            chromaGreenPrimary ( const double x_, const double y_ )

void            chromaGreenPrimary ( double *x_, double *y_ ) const

chromaRedPrimary

Chromaticity red primary point (e.g. x=0.64, y=0.33):

void            chromaRedPrimary ( const double x_, const double y_ )

void            chromaRedPrimary ( double *x_, double *y_ ) const

chromaWhitePoint

Chromaticity white point (e.g. x=0.3127, y=0.329):

void            chromaWhitePoint ( const double x_, const double y_ )
void            chromaWhitePoint ( double *x_, double *y_ ) const

classType

Image class (DirectClass or PseudoClass). NOTE: setting a DirectClass image to PseudoClass will result in the loss of color information if the number of colors in the image is greater than the maximum palette size (either 256 or 65536 entries depending on the value of QuantumDepth when ImageMagick was built):

void            classType ( const ClassType class_ )

ClassType       classType ( void ) const

clipMask

Associate a clip mask image with the current image. The clip mask image must have the same dimensions as the current image or an exception is thrown. Clipping occurs wherever pixels are transparent in the clip mask image. Clipping Pass an invalid image to unset an existing clip mask:

void            clipMask ( const Image & clipMask_ )

Image           clipMask ( void  ) const

colorFuzz

Colors within this distance are considered equal. A number of algorithms search for a target color. By default the color must be exact. Use this option to match colors that are close to the target color in RGB space:

void            colorFuzz ( const double fuzz_ )

double          colorFuzz ( void ) const

colorMap

Color at colormap position index:

void            colorMap ( const unsigned int index_,
                           const Color &color_ )

Color           colorMap ( const unsigned int index_ ) const

colorMapSize

Number of entries in the colormap. Setting the colormap size may extend or truncate the colormap. The maximum number of supported entries is specified by the MaxColormapSize constant, and is dependent on the value of QuantumDepth when GraphicsMagick is compiled. An exception is thrown if more entries are requested than may be supported. Care should be taken when truncating the colormap to ensure that the image colormap indexes reference valid colormap entries:

void            colorMapSize ( const unsigned int entries_ )

unsigned int    colorMapSize ( void )

colorSpace

The colorspace (e.g. CMYK) used to represent the image pixel colors:

void            colorSpace( const ColorspaceType colorSpace_ )

ColorspaceType  colorSpace ( void ) const

columns

Image width:

unsigned int    columns ( void ) const

comment

Image comment:

std::string     comment ( void ) const

compose

Composition operator to be used when composition is implicitly used (such as for image flattening):

void            compose (const CompositeOperator compose_)

CompositeOperator compose ( void ) const

compressType

Image compresion type. The default is the compression type of the input image file:

void            compressType ( const CompressionType compressType_ )

CompressionType compressType ( void ) const

debug

Enable printing of debug messages from GraphicsMagick as it executes:

void            debug ( const bool flag_ )

bool            debug ( void ) const

defineValue

Set or obtain a definition string to applied when encoding or decoding the specified format. The meanings of the definitions are format specific. The format is designated by the magick argument, the format-specific key is designated by key, and the associated value is specified by value. See the defineSet() method if the key must be removed entirely:

void            defineValue ( const std::string &magick_,
                              const std::string &key_,
                              const std::string &value_ )

std::string     defineValue ( const std::string &magick_,
                              const std::string &key_ ) const

defineSet

Set or obtain a definition flag to applied when encoding or decoding the specified format. Similar to the defineValue() method except that passing the flag value 'true' creates a value-less define with that format and key. Passing the flag value 'false' removes any existing matching definition. The method returns 'true' if a matching key exists, and 'false' if no matching key exists:

void            defineSet ( const std::string &magick_,
                            const std::string &key_,
                            bool flag_ )

bool            defineSet ( const std::string &magick_,
                            const std::string &key_ ) const

density

Vertical and horizontal resolution in pixels of the image. This option specifies an image density when decoding a Postscript or Portable Document page. Often used with psPageSize:

void            density ( const Geometry &geomery_ )

Geometry        density ( void ) const

depth

Image depth (bits allocated to red/green/blue components). Used to specify the bit depth when reading or writing raw images or when the output format supports multiple depths. Defaults to the quantum depth that GraphicsMagick is compiled with:

void            depth ( const unsigned int depth_ )

unsigned int    depth ( void ) const

directory

Tile names from within an image montage:

std::string     directory ( void ) const

endian

Endianness (LSBEndian like Intel, MSBEndian like SPARC, or NativeEndian for what this computer uses) for image formats which support endian-specific options:

void            endian ( const EndianType endian_ )

EndianType      endian ( void ) const

fileName

Image file name:

void            fileName ( const std::string &fileName_ )

std::string     fileName ( void ) const

fileSize

Number of bytes of the image on disk:

off_t          fileSize ( void ) const

fillColor

Color to use when filling drawn objects:

void            fillColor ( const Color &fillColor_ )

Color           fillColor ( void ) const

fillPattern

Pattern to use while filling drawn objects:

void            fillPattern ( const Image &fillPattern_ )

Image           fillPattern ( void  ) const

fillRule

Rule to use when filling drawn objects:

void            fillRule ( const FillRule &fillRule_ )

FillRule        fillRule ( void ) const

filterType

Filter to use when resizing image. The reduction filter employed has a sigificant effect on the time required to resize an image and the resulting quality. The default filter is Lanczos which has been shown to produce high quality results when reducing most images:

void            filterType ( const FilterTypes filterType_ )

FilterTypes     filterType ( void ) const

font

Text rendering font. If the font is a fully qualified X server font name, the font is obtained from an X server. To use a TrueType font, precede the TrueType filename with an @. Otherwise, specify a Postscript font name (e.g. "helvetica").:

void            font ( const std::string &font_ )

std::string     font ( void ) const

fontPointsize

Text rendering font point size:

void            fontPointsize ( const double pointSize_ )

double          fontPointsize ( void ) const

fontTypeMetrics

Obtain font metrics (see TypeMetric) for text string given current font, pointsize, and density settings. This information is necessary in order to do fancy layout of text:

void            fontTypeMetrics( const std::string &text_,
                                 TypeMetric *metrics )

format

Long image format description:

std::string     format ( void ) const

gamma

Gamma level of the image. Gamma is a pow() function which converts between the linear light representation and the representation for the computer display. Most computer images are gamma corrected to 2.2 (1/0.4545) so that each step results in a visually linear step on a computer or video display:

double          gamma ( void ) const

geometry

Preferred size of the image when encoding:

Geometry        geometry ( void ) const

gifDisposeMethod

GIF disposal method. This option (specific to the GIF file format) is used to control how successive frames are rendered (how the preceding frame is disposed of) when creating a GIF animation:

void            gifDisposeMethod ( const unsigned int disposeMethod_ )

unsigned int    gifDisposeMethod ( void ) const

iccColorProfile

ICC color profile. Supplied via a Blob since Magick++/ and GraphicsMagick do not currently support formating this data structure directly. Specifications are available from the International Color Consortium for the format of ICC color profiles:

void            iccColorProfile( const Blob &colorProfile_ )

Blob            iccColorProfile( void ) const

interlaceType

The type of interlacing scheme (default NoInterlace ). This option is used to specify the type of interlacing scheme for raw image formats such as RGB or YUV. NoInterlace means do not interlace, LineInterlace uses scanline interlacing, and PlaneInterlace uses plane interlacing. PartitionInterlace is like PlaneInterlace except the different planes are saved to individual files (e.g. image.R, image.G, and image.B). Use LineInterlace or PlaneInterlace to create an interlaced GIF or progressive JPEG image:

void            interlaceType ( const InterlaceType interlace_ )

InterlaceType   interlaceType ( void ) const

iptcProfile

IPTC profile. Supplied via a Blob since Magick++ and GraphicsMagick do not currently support formating this data structure directly. Specifications are available from the International Press Telecommunications Council for IPTC profiles:

void            iptcProfile( const Blob& iptcProfile_ )

Blob            iptcProfile( void ) const

isValid

Does object contain valid image? Set to false in order to invalidate the image. Images constructed via the default constructor are invalid images and isValid() will return false:

void            isValid ( const bool isValid_ )

bool            isValid ( void ) const

label

Image label:

std::string     label ( void ) const

lineWidth

Stroke width for drawing vector objects (default one) This method is now deprecated. Please use strokeWidth instead:

void            lineWidth ( const double lineWidth_ )

double          lineWidth ( void ) const

magick

File type magick identifier (.e.g "GIF"):

void            magick ( const std::string &magick_ )

std::string     magick ( void ) const

matte

Image supports transparency (matte channel):

void            matte ( const bool matteFlag_ )

bool            matte ( void ) const

matteColor

Image matte (frame) color:

void            matteColor ( const Color &matteColor_ )

Color           matteColor ( void ) const

meanErrorPerPixel

The mean error per pixel computed when an image is color reduced. This parameter is only valid if verbose is set to true and the image has just been quantized:

double          meanErrorPerPixel ( void ) const

modulusDepth

Image modulus depth (minimum number of bits required to support red/green/blue components without loss of accuracy). The pixel modulus depth may be decreased by supplying a value which is less than the current value, updating the pixels (reducing accuracy) to the new depth. The pixel modulus depth can not be increased over the current value using this method:

void            modulusDepth ( const unsigned int modulusDepth_ )

unsigned int    modulusDepth ( void ) const

monochrome

Transform image to black and white while color reducing (quantizing):

void            monochrome ( const bool monochromeFlag_ )

bool            monochrome ( void ) const

montageGeometry

Tile size and offset within an image montage. Only valid for montage images:

Geometry        montageGeometry ( void ) const

normalizedMaxError

The normalized max error per pixel computed when an image is color reduced. This parameter is only valid if verbose is set to true and the image has just been quantized:

double          normalizedMaxError ( void ) const

normalizedMeanError

The normalized mean error per pixel computed when an image is color reduced. This parameter is only valid if verbose is set to true and the image has just been quantized:

double          normalizedMeanError ( void ) const

orientation

Image orientation. Supported by some file formats such as DPX and TIFF. Useful for turning the right way up:

void            orientation ( const OrientationType orientation_ )

OrientationType orientation ( void ) const

page

Preferred size and location of an image canvas.

Use this option to specify the dimensions and position of the Postscript page in dots per inch or a TEXT page in pixels. This option is typically used in concert with density .

Page may also be used to position a GIF image (such as for a scene in an animation):

void            page ( const Geometry &pageSize_ )

Geometry        page ( void ) const

pixelColor

Get/set pixel color at location x & y:

void            pixelColor ( const unsigned int x_,
                             const unsigned int y_,
                             const Color &color_ )

Color           pixelColor ( const unsigned int x_,
                             const unsigned int y_ ) const

profile

Add or remove a named profile to/from the image. Remove the profile by passing an empty Blob (e.g. Blob()). Valid names are "*", "8BIM", "ICM", "IPTC", or a user/format-defined profile name:

void            profile( const std::string name_,
                         const Blob &colorProfile_ )

Retrieve a named profile from the image. Valid names are: "8BIM", "8BIMTEXT", "APP1", "APP1JPEG", "ICC", "ICM", & "IPTC" or an existing user/format-defined profile name:

Blob            profile( const std::string name_ ) const

quality

JPEG/MIFF/PNG compression level (default 75):

void            quality ( const unsigned int quality_ )

unsigned int    quality ( void ) const

quantizeColors

Maximum number of colors to quantize to:

void            quantizeColors ( const unsigned int colors_ )

unsigned int    quantizeColors ( void ) const

quantizeColorSpace

Colorspace to quantize in (default RGB). Empirical evidence suggests that distances in color spaces such as YUV or YIQ correspond to perceptual color differences more closely than do distances in RGB space. These color spaces may give better results when color reducing an image:

void            quantizeColorSpace ( const ColorspaceType colorSpace_ )

ColorspaceType  quantizeColorSpace ( void ) const

quantizeDither

Apply Floyd/Steinberg error diffusion to the image. The basic strategy of dithering is to trade intensity resolution for spatial resolution by averaging the intensities of several neighboring pixels. Images which suffer from severe contouring when reducing colors can be improved with this option. The quantizeColors or monochrome option must be set for this option to take effect:

void            quantizeDither ( const bool ditherFlag_ )

bool            quantizeDither ( void ) const

quantizeTreeDepth

Depth of the quantization color classification tree. Values of 0 or 1 allow selection of the optimal tree depth for the color reduction algorithm. Values between 2 and 8 may be used to manually adjust the tree depth:

void            quantizeTreeDepth ( const unsigned int treeDepth_ )

unsigned int    quantizeTreeDepth ( void ) const

renderingIntent

The type of rendering intent (used when applying an ICC color profile):

void            renderingIntent ( const RenderingIntent renderingIntent_ )

RenderingIntent renderingIntent ( void ) const

resolutionUnits

Units of image resolution:

void            resolutionUnits ( const ResolutionType resolutionUnits_ )

ResolutionType  resolutionUnits ( void ) const

rows

The number of pixel rows in the image:

unsigned int    rows ( void ) const

scene

Image scene number:

void            scene ( const unsigned int scene_ )

unsigned int    scene ( void ) const

signature

Image textual signature. Set force to true in order to re-calculate the signature regardless of whether the image data has been modified:

std::string     signature ( const bool force_ = false ) const

size

Width and height of a raw image (an image which does not support width and height information). Size may also be used to affect the image size read from a multi-resolution format (e.g. Photo CD, JBIG, or JPEG:

void            size ( const Geometry &geometry_ )

Geometry        size ( void ) const

statistics

Obtain image statistics. Statistics are normalized to the range of 0.0 to 1.0 and are output to the specified ImageStatistics structure:

void            statistics ( ImageStatistics *statistics ) const

strokeAntiAlias

Enable/disable stroke anti-aliasing:

void            strokeAntiAlias( const bool flag_ )

bool            strokeAntiAlias( void ) const

strokeColor

Color to use when drawing object outlines:

void            strokeColor ( const Color &strokeColor_ )

Color           strokeColor ( void ) const

strokeDashArray

Specify the pattern of dashes and gaps used to stroke paths. The strokeDashArray represents a zero-terminated array of numbers that specify the lengths of alternating dashes and gaps in pixels. If an odd number of values is provided, then the list of values is repeated to yield an even number of values. A typical strokeDashArray array might contain the members 5 3 2 0, where the zero value indicates the end of the pattern array:

void            strokeDashArray ( const double* strokeDashArray_ )

const double*   strokeDashArray ( void ) const

strokeDashOffset

While drawing using a dash pattern, specify distance into the dash pattern to start the dash (default 0):

void            strokeDashOffset ( const double strokeDashOffset_ )

double          strokeDashOffset ( void ) const

strokeLineCap

Specify the shape to be used at the end of open subpaths when they are stroked. Values of LineCap are UndefinedCap, ButtCap, RoundCap, and SquareCap:

void            strokeLineCap ( const LineCap lineCap_ )

LineCap         strokeLineCap ( void ) const

strokeLineJoin

Specify the shape to be used at the corners of paths (or other vector shapes) when they are stroked. Values of LineJoin are UndefinedJoin, MiterJoin, RoundJoin, and BevelJoin:

void            strokeLineJoin ( const LineJoin lineJoin_ )

LineJoin        strokeLineJoin ( void ) const

strokeMiterLimit

Specify miter limit. When two line segments meet at a sharp angle and miter joins have been specified for 'lineJoin', it is possible for the miter to extend far beyond the thickness of the line stroking the path. The miterLimit' imposes a limit on the ratio of the miter length to the 'lineWidth'. The default value of this parameter is 4:

void            strokeMiterLimit ( const unsigned int miterLimit_ )

unsigned int    strokeMiterLimit ( void ) const

strokePattern

Pattern image to use while stroking object outlines:

void            strokePattern ( const Image &strokePattern_ )

Image           strokePattern ( void  ) const

strokeWidth

Stroke width for drawing vector objects (default one):

void            strokeWidth ( const double strokeWidth_ )

double          strokeWidth ( void ) const

subImage

Subimage of an image sequence:

void            subImage ( const unsigned int subImage_ )

unsigned int    subImage ( void ) const

subRange

Number of images relative to the base image:

void            subRange ( const unsigned int subRange_ )

unsigned int    subRange ( void ) const

textEncoding

Annotation text encoding (e.g. "UTF-16"):

void            textEncoding ( const std::string &encoding_ )

std::string     textEncoding ( void ) const

tileName

Tile name:

void            tileName ( const std::string &tileName_ )

std::string     tileName ( void ) const

totalColors

Number of colors in the image:

unsigned long   totalColors ( void )

transformOrigin

Origin of coordinate system to use when annotating with text or drawing:

void            transformOrigin ( const double x_,const  double y_ )

transformRotation

Rotation to use when annotating with text or drawing:

void            transformRotation ( const double angle_ )

transformReset

Reset transformation parameters to default:

void            transformReset ( void )

transformScale

Scale to use when annotating with text or drawing:

void            transformScale ( const double sx_, const double sy_ )

transformSkewX

Skew to use in X axis when annotating with text or drawing:

void            transformSkewX ( const double skewx_ )

transformSkewY

Skew to use in Y axis when annotating with text or drawing:

void            transformSkewY ( const double skewy_ )

verbose

Print detailed information about the image:

void            verbose ( const bool verboseFlag_ )

bool            verbose ( void ) const

view

FlashPix viewing parameters:

void            view ( const std::string &view_ )

std::string     view ( void ) const

x11Display

X11 display to display to, obtain fonts from, or to capture image from:

void            x11Display ( const std::string &display_ )

std::string     x11Display ( void ) const

xResolution

x resolution of the image:

double          xResolution ( void ) const

yResolution

y resolution of the image:

double          yResolution ( void ) const

Low-Level Image Pixel Access

Image pixels (of type PixelPacket ) may be accessed directly via the Image Pixel Cache . The image pixel cache is a rectangular window into the actual image pixels (which may be in memory, memory-mapped from a disk file, or entirely on disk). Two interfaces exist to access the Image Pixel Cache. The interface described here (part of the Image class) supports only one view at a time. See the Pixels class for a more abstract interface which supports simultaneous pixel views (up to the number of rows). As an analogy, the interface described here relates to the Pixels class as stdio's gets() relates to fgets(). The Pixels class provides the more general form of the interface.

Obtain existing image pixels via getPixels(). Create a new pixel region using setPixels().

In order to ensure that only the current generation of the image is modified, the Image's modifyImage() method should be invoked to reduce the reference count on the underlying image to one. If this is not done, then it is possible for a previous generation of the image to be modified due to the use of reference counting when copying or constructing an Image.

Depending on the capabilities of the operating system, and the relationship of the window to the image, the pixel cache may be a copy of the pixels in the selected window, or it may be the actual image pixels. In any case calling syncPixels() insures that the base image is updated with the contents of the modified pixel cache. The method readPixels() supports copying foreign pixel data formats into the pixel cache according to the QuantumTypes. The method writePixels() supports copying the pixels in the cache to a foreign pixel representation according to the format specified by QuantumTypes.

The pixel region is effectively a small image in which the pixels may be accessed, addressed, and updated, as shown in the following example:

pixel_cache

// Construct image based on an existing file
Image image("cow.png");

// Ensure that there are no other references to this image.
image.modifyImage();

// Set the image type to TrueColor DirectClass representation.
image.type(TrueColorType);

// Request pixel region with size 60x40, and top origin at 20x30
int columns = 60;
PixelPacket *pixel_cache = image.getPixels(20,30,columns,40);

// Set pixel at column 5, and row 10 in the pixel cache to red.
int column = 5;
int row = 10;
PixelPacket *pixel = pixel_cache+row*columns+column;
*pixel = Color("red");

// Save changes to underlying image .
image.syncPixels();

 // Save updated image to file.
image.write("horse.png");

The image cache supports the following methods:

getConstPixels

Transfers read-only pixels from the image to the pixel cache as defined by the specified region:

const PixelPacket* getConstPixels ( const int x_, const int y_,
                                    const unsigned int columns_,
                                    const unsigned int rows_ ) const

getIndexes

Obtain mutable image pixel indexes (valid for PseudoClass images):

IndexPacket* getIndexes ( void )

getConstIndexes

Obtain immutable image pixel indexes (valid for PseudoClass images):

const IndexPacket* getConstIndexes ( void ) const

getPixels

Transfers pixels from the image to the pixel cache as defined by the specified region. Modified pixels may be subsequently transferred back to the image via syncPixels. This method is valid for DirectClass images:

PixelPacket* getPixels ( const int x_, const int y_,
                         const unsigned int columns_,
                         const unsigned int rows_ )

setPixels

Allocates a pixel cache region to store image pixels as defined by the region rectangle. This area is subsequently transferred from the pixel cache to the image via syncPixels:

PixelPacket* setPixels ( const int x_, const int y_,
                         const unsigned int columns_,
                         const unsigned int rows_ )

syncPixels

Transfers the image cache pixels to the image:

void syncPixels ( void )

readPixels

Transfers one or more pixel components from a buffer or file into the image pixel cache of an image. Used to support image decoders:

void readPixels ( const QuantumType quantum_,
                  const unsigned char *source_ )

writePixels

Transfers one or more pixel components from the image pixel cache to a buffer or file. Used to support image encoders:

void writePixels ( const QuantumType quantum_,
                   unsigned char *destination_ )

Copyright © Bob Friesenhahn 1999 - 2014