GraphicsMagick Types

AffineMatrix

AffineMatrix defines a 2D affine matrix transform.

typedef struct _AffineMatrix
{
  double
    sx,
    rx,
    ry,
    sy,
    tx,
    ty;
} AffineMatrix;

BlobInfo

BlobInfo is an opaque pointer reference to the internal structure of an I/O blob handle.

Cache

typedef void
  *Cache;

ChannelType

typedef enum
{
  UndefinedChannel,
  RedChannel,     /* RGB Red channel */
  CyanChannel,    /* CMYK Cyan channel */
  GreenChannel,   /* RGB Green channel */
  MagentaChannel, /* CMYK Magenta channel */
  BlueChannel,    /* RGB Blue channel */
  YellowChannel,  /* CMYK Yellow channel */
  OpacityChannel, /* Opacity channel */
  BlackChannel,   /* CMYK Black (K) channel */
  MatteChannel,   /* Same as Opacity channel (deprecated) */
  AllChannels,    /* Color channels */
  GrayChannel     /* Color channels represent an intensity. */
} ChannelType;

ChromaticityInfo

The ChromaticityInfo structure is used to represent chromaticity (colorspace primary coordinates in xy space) values for images in GraphicsMagick.

The members of the ChromaticityInfo structure are shown in the following table:

ChromaticityInfo Structure Members
Member Type Description
red_primary PointInfo Chromaticity red primary point (e.g. x=0.64, y=0.33)
green_primary PointInfo Chromaticity green primary point (e.g. x=0.3, y=0.6)
blue_primary PointInfo Chromaticity blue primary point (e.g. x=0.15, y=0.06)
white_point PointInfo Chromaticity white point (e.g. x=0.3127, y=0.329)

ClassType

ClassType enumeration specifies the image storage class.

ClassType
Enumeration Description
UndefinedClass Unset value.
DirectClass Image is composed of pixels which represent literal color values.
PseudoClass Image is composed of pixels which specify an index in a color palette.

ClipPathUnits

typedef enum
{
  UserSpace,
  UserSpaceOnUse,
  ObjectBoundingBox
} ClipPathUnits;

ColorPacket

typedef struct _ColorPacket
{
  PixelPacket
    pixel;

  unsigned short
    index;

  unsigned long
    count;
} ColorPacket;

ColorspaceType

The ColorspaceType enumeration is used to specify the colorspace that quantization (color reduction and mapping) is done under or to specify the colorspace when encoding an output image. Colorspaces are ways of describing colors to fit the requirements of a particular application (e.g. Television, offset printing, color monitors). Color reduction, by default, takes place in the RGBColorspace. Empirical evidence suggests that distances in color spaces such as YUVColorspace or YIQColorspace correspond to perceptual color differences more closely han do distances in RGB space. These color spaces may give better results when color reducing an image. Refer to quantize for more details.

When encoding an output image, the colorspaces RGBColorspace, CMYKColorspace, and GRAYColorspace may be specified. The CMYKColorspace option is only applicable when writing TIFF, JPEG, and Adobe Photoshop bitmap (PSD) files.

ColorspaceType
Enumeration Description
UndefinedColorspace Unset value.
RGBColorspace Red, Green, Blue colorspace.
GRAYColorspace Similar to Luma (Y) according to ITU-R 601
TransparentColorspace RGB which preserves the matte while quantizing colors.
OHTAColorspace  
XYZColorspace CIE XYZ
YCCColorspace Kodak PhotoCD PhotoYCC
YIQColorspace  
YPbPrColorspace  
YUVColorspace YUV colorspace as used for computer video.
CMYKColorspace Cyan, Magenta, Yellow, Black colorspace.
sRGBColorspace Kodak PhotoCD sRGB
HSLColorspace Hue, saturation, luminosity
HWBColorspace Hue, whiteness, blackness
LABColorspace ITU LAB
CineonLogRGBColorspace RGB data with Cineon Log scaling, 2.048 density range
Rec601LumaColorspace Luma (Y) according to ITU-R 601
Rec601YCbCrColorspace YCbCr according to ITU-R 601
Rec709LumaColorspace Luma (Y) according to ITU-R 709
Rec709YCbCrColorspace YCbCr according to ITU-R 709

ComplianceType

typedef enum
{
  UndefinedCompliance = 0x0000,
  NoCompliance = 0x0000,
  SVGCompliance = 0x0001,
  X11Compliance = 0x0002,
  XPMCompliance = 0x0004,
  AllCompliance = 0xffff
} ComplianceType;

CompositeOperator

CompositeOperator is used to select the image composition algorithm used to compose a composite image with an image. By default, each of the composite image pixels are replaced by the corresponding image tile pixel. Specify CompositeOperator to select a different algorithm.

The image compositor requires a matte, or alpha channel in the image for some operations. This extra channel usually defines a mask which represents a sort of a cookie-cutter for the image. This is the case when matte is 255 (full coverage) for pixels inside the shape, zero outside, and between zero and 255 on the boundary. For certain operations, if image does not have a matte channel, it is initialized with 0 for any pixel matching in color to pixel location (0,0), otherwise 255 (to work properly borderWidth must be 0).

CompositeOperator
Enumeration Description
UndefinedCompositeOp Unset value.
OverCompositeOp The result is the union of the the two image shapes with the composite image obscuring image in the region of overlap.
InCompositeOp The result is a simply composite image cut by the shape of image. None of the image data of image is included in the result.
OutCompositeOp The resulting image is composite image with the shape of image cut out.
AtopCompositeOp The result is the same shape as image image, with composite image obscuring image there the image shapes overlap. Note that this differs from OverCompositeOp because the portion of composite image outside of image's shape does not appear in the result.
XorCompositeOp The result is the image data from both composite image and image that is outside the overlap region. The overlap region will be blank.
PlusCompositeOp The result is just the sum of the image data. Output values are cropped to 255 (no overflow). This operation is independent of the matte channels.
MinusCompositeOp The result of composite image - image, with overflow cropped to zero. The matte chanel is ignored (set to 255, full coverage).
AddCompositeOp The result of composite image + image, with overflow wrapping around (mod 256).
SubtractCompositeOp The result of composite image - image, with underflow wrapping around (mod 256). The add and subtract operators can be used to perform reversible transformations.
DifferenceCompositeOp The result of abs(composite image - image). This is useful for comparing two very similar images.
BumpmapCompositeOp The result image shaded by composite image.
CopyCompositeOp The resulting image is image replaced with composite image. Here the matte information is ignored.
CopyRedCompositeOp The resulting image is the red layer in image replaced with the red layer in composite image. The other layers are copied untouched.
CopyGreenCompositeOp The resulting image is the green layer in image replaced with the green layer in composite image. The other layers are copied untouched.
CopyBlueCompositeOp The resulting image is the blue layer in image replaced with the blue layer in composite image. The other layers are copied untouched.
CopyOpacityCompositeOp The resulting image is the matte layer in image replaced with the matte layer in composite image. The other layers are copied untouched.
ClearCompositeOp Pixels in the region are set to Transparent.
DissolveCompositeOp  
DisplaceCompositeOp  
ModulateCompositeOp Modulate brightness in HSL space.
ThresholdCompositeOp  
NoCompositeOp Do nothing at all.
DarkenCompositeOp  
LightenCompositeOp  
HueCompositeOp Copy Hue channel (from HSL colorspace).
SaturateCompositeOp Copy Saturation channel (from HSL colorspace).
ColorizeCompositeOp Copy Hue and Saturation channels (from HSL colorspace).
LuminizeCompositeOp Copy Brightness channel (from HSL colorspace).
ScreenCompositeOp [Not yet implemented]
OverlayCompositeOp [Not yet implemented]
CopyCyanCompositeOp Copy the Cyan channel.
CopyMagentaCompositeOp Copy the Magenta channel.
CopyYellowCompositeOp Copy the Yellow channel.
CopyBlackCompositeOp Copy the Black channel.
DivideCompositeOp  

CompressionType

CompressionType is used to express the desired compression type when encoding an image. Be aware that most image types only support a sub-set of the available compression types. If the compression type specified is incompatable with the image, GraphicsMagick selects a compression type compatable with the image type.

CompressionType
Enumeration Description
UndefinedCompression Unset value.
NoCompression No compression
BZipCompression BZip (Burrows-Wheeler block-sorting text compression algorithm and Huffman coding) as used by bzip2 utilities
FaxCompression CCITT Group 3 FAX compression
Group4Compression CCITT Group 4 FAX compression (used only for TIFF)
JPEGCompression JPEG compression
LosslessJPEGCompression Lossless JPEG compression
LZWCompression Lempel-Ziv-Welch (LZW) compression (caution, patented by Unisys)
RLECompression Run-Length encoded (RLE) compression
ZipCompression Lempel-Ziv compression (LZ77) as used in PKZIP and GNU gzip.

DecorationType

typedef enum
{
  NoDecoration,
  UnderlineDecoration,
  OverlineDecoration,
  LineThroughDecoration
} DecorationType;

DrawContext

typedef struct _DrawContext *DrawContext;

DrawInfo

The DrawInfo structure is used to support annotating an image using drawing commands.

Methods Supporting DrawInfo
Method Description
GetDrawInfo() Allocate new structure with defaults set.
CloneDrawInfo() Copy existing structure, allocating new structure in the process.
DestroyDrawInfo() Deallocate structure, including any members.
DrawImage() Render primitives to image.

The members of the DrawInfo structure are shown in the following table. The structure is initialized to reasonable defaults by first initializing the equivalent members of ImageInfo, and then initializing the entire structure using GetDrawInfo().

DrawInfo Structure Members Supporting DrawImage()
Member Type Description
affine AffineInfo Coordinate transformation (rotation, scaling, and translation).
border_color PixelPacket Border color
box PixelPacket Text solid background color.
decorate DecorationType Text decoration type.
density char * Text rendering density in DPI (effects scaling font according to pointsize). E.g. "72x72"
fill PixelPacket Object internal fill (within outline) color.
font char * Font to use when rendering text.
gravity GravityType Text placement preference (e.g. NorthWestGravity).
linewidth double Stroke (outline) drawing width in pixels.
pointsize double Font size (also see density).
primitive char * Space or new-line delimited list of text drawing primitives (e.g "text 100,100 Cockatoo"). See the table Drawing Primitives for the available drawing primitives.
stroke PixelPacket Object stroke (outline) color.
stroke_antialias unsigned int Set to True (non-zero) to obtain anti-aliased stroke rendering.
text_antialias unsigned int Set to True (non-zero) to obtain anti-aliased text rendering.
tile Image * Image texture to draw with. Use an image containing a single color (e.g. a 1x1 image) to draw in a solid color.

Drawing Primitives

The drawing primitives shown in the following table may be supplied as a space or new-line delimited list to the primitive member. Primitives which set drawing options effect the results from subsequent drawing operations. See the 'push graphic-context' and 'pop graphic-context' primitives for a way to control the propagation of drawing options.

Drawing Primitives
Primitive Arguments Purpose
affine sx,rx,ry,sy,tx,ty Apply coordinate transformations to support scaling (s), rotation (r), and translation (t). Angles are specified in radians. Equivalent to SVG matrix command which supplies a transformation matrix.
angle angle Specify object drawing angle.
arc startX,startY endX,endY startDegrees,endDegrees Draw an arc.
Bezier x1,y1, x2,y2, x3,y3, ..., xN,yN Draw a Bezier curve.
circle originX,originY perimX,perimY Draw a circle.
color x,y (point|replace| floodfill|filltoborder| reset) Set color in image according to specified colorization rule.
decorate (none|underline|overline| line-through) Specify text decoration.
ellipse originX,originY width,height arcStart,arcEnd Draw an ellipse.
fill colorspec Specifiy object filling color.
fill-opacity opacity Specify object fill opacity.
font fontname Specify text drawing font.
gravity (NorthWest,North,NorthEast, West,Center,East, SouthWest,South,SouthEast) Specify text positioning gravity.
image x,y width,height filename Composite image at position, scaled to specified width and height, and specified filename. If width or height is zero, scaling is not performed.
line startX,startY endX,endY Draw a line.
matte x,y (point|replace| floodfill|filltoborder| reset) Set matte in image according to specified colorization rule.
opacity fillOpacity strokeOpacity Specify drawing fill and stroke opacities.
path 'SVG-compatible path arguments' Draw using SVG-compatible path drawing commands.
point x,y Set point to fill color.
pointsize pointsize Specify text drawing pointsize (scaled to density).
polygon x1,y1, x2,y2, x3,y3, ..., xN,yN Draw a polygon.
polyline x1,y1, x2,y2, x3,y3, ..., xN,yN Draw a polyline.
pop graphic-context Remove options set since previous "push graphic-context" command. Options revert to those in effect prior to pushing the graphic context.
push graphic-context Specify new graphic context.
rect upperLeftX,upperLeftY lowerRightX,lowerRightY Draw a rectangle.
rotate angle Specify coordiante space rotation. Subsequent objects are drawn with coordate space rotated by specified angle.
roundrectangle centerX,centerY width,hight cornerWidth,cornerHeight Draw a rectangle with rounded corners.
stroke colorspec Specify object stroke (outline) color.
stroke-antialias stroke_antialias (0 or 1) Specify if stroke should be antialiased or not.
stroke-dash value Specify pattern to be used when drawing stroke.
stroke-opacity opacity Specify opacity of stroke drawing color.
stroke-width linewidth Specify stroke (outline) width in pixels.
text x,y "some text" Draw text at position.
text-antialias text_antialias (0 or 1) Specify if rendered text is to be antialiased (blend edges).
scale x,y Specify scaling to be applied to coordintate space for subsequent drawing commands.
translate x,y Specify center of coordinate space to use for subsequent drawing commands.

EndianType

typedef enum
{
  UndefinedEndian,
  LSBEndian,            /* "little" endian */
  MSBEndian,            /* "big" endian */
  NativeEndian          /* native endian */
} EndianType;

ErrorHandler

typedef void
  (*ErrorHandler)(const ExceptionType,const char *,const char *);

ExceptionInfo

typedef struct _ExceptionInfo
{
  char
    *reason,
    *description;

  ExceptionType
    severity;

  unsigned long
    signature;
} ExceptionInfo;

ExceptionType

typedef enum
{
  UndefinedException,
  WarningException = 300,
  ResourceLimitWarning = 300,
  TypeWarning = 305,
  OptionWarning = 310,
  DelegateWarning = 315,
  MissingDelegateWarning = 320,
  CorruptImageWarning = 325,
  FileOpenWarning = 330,
  BlobWarning = 335,
  StreamWarning = 340,
  CacheWarning = 345,
  CoderWarning = 350,
  ModuleWarning = 355,
  DrawWarning = 360,
  ImageWarning = 365,
  XServerWarning = 380,
  MonitorWarning = 385,
  RegistryWarning = 390,
  ConfigureWarning = 395,
  ErrorException = 400,
  ResourceLimitError = 400,
  TypeError = 405,
  OptionError = 410,
  DelegateError = 415,
  MissingDelegateError = 420,
  CorruptImageError = 425,
  FileOpenError = 430,
  BlobError = 435,
  StreamError = 440,
  CacheError = 445,
  CoderError = 450,
  ModuleError = 455,
  DrawError = 460,
  ImageError = 465,
  XServerError = 480,
  MonitorError = 485,
  RegistryError = 490,
  ConfigureError = 495,
  FatalErrorException = 700,
  ResourceLimitFatalError = 700,
  TypeFatalError = 705,
  OptionFatalError = 710,
  DelegateFatalError = 715,
  MissingDelegateFatalError = 720,
  CorruptImageFatalError = 725,
  FileOpenFatalError = 730,
  BlobFatalError = 735,
  StreamFatalError = 740,
  CacheFatalError = 745,
  CoderFatalError = 750,
  ModuleFatalError = 755,
  DrawFatalError = 760,
  ImageFatalError = 765,
  XServerFatalError = 780,
  MonitorFatalError = 785,
  RegistryFatalError = 790,
  ConfigureFatalError = 795
} ExceptionType;

FillRule

typedef enum
{
  UndefinedRule,
  EvenOddRule,
  NonZeroRule
} FillRule;

FilterTypes

FilterTypes is used to adjust the filter algorithm used when resizing images. Different filters experience varying degrees of success with various images and can take significantly different amounts of processing time. GraphicsMagick uses the LanczosFilter by default since this filter has been shown to provide the best results for most images in a reasonable amount of time. Other filter types (e.g. TriangleFilter) may execute much faster but may show artifacts when the image is re-sized or around diagonal lines. The only way to be sure is to test the filter with sample images.

FilterTypes
Enumeration Description
UndefinedFilter Unset value.
PointFilter Point Filter
BoxFilter Box Filter
TriangleFilter Triangle Filter
HermiteFilter Hermite Filter
HanningFilter Hanning Filter
HammingFilter Hamming Filter
BlackmanFilter Blackman Filter
GaussianFilter Gaussian Filter
QuadraticFilter Quadratic Filter
CubicFilter Cubic Filter
CatromFilter Catrom Filter
MitchellFilter Mitchell Filter
LanczosFilter Lanczos Filter
BesselFilter Bessel Filter
SincFilter Sinc Filter

FrameInfo

typedef struct _FrameInfo
{
  unsigned long
    width,
    height;

  long
    x,
    y,
    inner_bevel,
    outer_bevel;
} FrameInfo;

GravityType

GravityType specifies positioning of an object (e.g. text, image) within a bounding region (e.g. an image). Gravity provides a convenient way to locate objects irrespective of the size of the bounding region, in other words, you don't need to provide absolute coordinates in order to position an object. A common default for gravity is NorthWestGravity.

GravityType
Enumeration Description
ForgetGravity Don't use gravity.
NorthWestGravity Position object at top-left of region.
NorthGravity Postiion object at top-center of region
NorthEastGravity Position object at top-right of region
WestGravity Position object at left-center of region
CenterGravity Position object at center of region
EastGravity Position object at right-center of region
SouthWestGravity Position object at left-bottom of region
SouthGravity Position object at bottom-center of region
SouthEastGravity Position object at bottom-right of region

Image

The Image structure represents an GraphicsMagick image. It is initially allocated by AllocateImage() and deallocated by DestroyImage(). The functions ReadImage(), ReadImages(), BlobToImage() and CreateImage() return a new image. Use CloneImage() to copy an image. An image consists of a structure containing image attributes as well as the image pixels.

The image pixels are represented by the structure PixelPacket and are cached in-memory, or on disk, depending on the cache threshold setting. This cache is known as the "pixel cache". Pixels in the cache may not be edited directly. They must first be made visible from the cache via a pixel view. A pixel view is a rectangular view of the pixels as defined by a starting coordinate, and a number of rows and columns. When considering the varying abilities of multiple platforms, the most reliably efficient pixel view is comprized of part, or all, of one image row.

There are two means of accessing pixel views. When using the default view, the pixels are made visible and accessable by using the GetImagePixels() method which provides access to a specified region of the image. After the view has been updated, the pixels may be saved back to the cache in their original positions via SyncImagePixels(). In order to create an image with new contents, or to blindly overwrite existing contents, the method SetImagePixels() is used to reserve a pixel view corresponding to a region in the pixel cache. Once the pixel view has been updated, it may be written to the cache via SyncImagePixels(). The function GetIndexes() provides access to the image colormap, represented as an array of type IndexPacket.

A more flexible interface to the image pixels is via the Cache View interface. This interface supports multiple pixel cache views (limited by the amount of available memory), each of which are identified by a handle (of type ViewInfo). Use OpenCacheView() to obtain a new cache view, CloseCacheView() to discard a cache view, GetCacheViewPixels() to access an existing pixel region, SetCacheView() to define a new pixel region, and SyncCacheViewPixels() to save the updated pixel region. The function GetCacheViewIndexes() provides access to the colormap indexes associated with the pixel view.

When writing encoders and decoders for new image formats, it is convenient to have a high-level interface available which supports converting between external pixel representations and GraphicsMagick's own representation. Pixel components (red, green, blue, opacity, RGB, or RGBA) may be transferred from a user-supplied buffer into the default view by using ImportImagePixelArea(), or from an allocated view via ImportViewPixelArea(). Pixel components may be transferred from the default view into a user-supplied buffer by using ExportImagePixelArea(), or from an allocated view via ExportViewPixelArea(). Use of this high-level interface helps protect image coders from changes to GraphicsMagick's pixel representation and simplifies the implementation.

The members of the Image structure are shown in the following table:

Image Structure Members
Member Type Description
background_color PixelPacket Image background color
blur double Blur factor to apply to the image when zooming
border_color PixelPacket Image border color
chromaticity ChromaticityInfo Red, green, blue, and white-point chromaticity values.
colormap PixelPacket * PseudoColor palette array.
colors unsigned int The desired number of colors. Used by QuantizeImage().
colorspace ColorspaceType Image pixel interpretation.If the colorspace is RGB the pixels are red, green, blue. If matte is true, then red, green, blue, and index. If it is CMYK, the pixels are cyan, yellow, magenta, black. Otherwise the colorspace is ignored.
columns unsigned int Image width
compression CompressionType Image compresion type. The default is the compression type of the specified image file.
delay unsigned int 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.
depth unsigned int Image depth. Number of encoding bits per sample. Usually 8 or 16, but sometimes 10 or 12.
directory char * Tile names from within an image montage. Only valid after calling MontageImages() or reading a MIFF file which contains a directory.
dispose unsigned int GIF disposal method. This option is used to control how successive frames are rendered (how the preceding frame is disposed of) when creating a GIF animation.
exception ExceptionInfo Record of any error which occurred when updating image.
filename char [MaxTextExtent] Image file name to read or write.
filter FilterTypes Filter to use when resizing image. The reduction filter employed has a significant 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.
fuzz int 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.
gamma double Gamma level of the image. The same color image displayed on two different workstations may look different due to differences in the display monitor. Use gamma correction to adjust for this color difference.
geometry char * Preferred size of the image when encoding.
interlace 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.
iterations unsigned int Number of iterations to loop an animation (e.g. Netscape loop extension) for.
magick char [MaxTextExtent] Image encoding format (e.g. "GIF").
magick_columns unsigned int Base image width (before transformations)
magick_filename char [MaxTextExtent] Base image filename (before transformations)
magick_rows unsigned int Base image height (before transformations)
matte unsigned int If non-zero, then the index member of pixels represents the alpha channel.
matte_color PixelPacket Image matte (transparent) color
montage char * Tile size and offset within an image montage. Only valid for montage images.
next struct _Image * Next image frame in sequence
offset int Number of initial bytes to skip over when reading raw image.
orientation OrientationType Orientation of the image. Specifies scanline orientation and starting coordinate of image.
page RectangleInfo Equivalent size of Postscript page.
previous struct _Image * Previous image frame in sequence.
rendering_intent RenderingIntent The type of rendering intent.
rows unsigned int Image height
scene unsigned int Image frame scene number.
storage_class ClassType Image storage class. If DirectClass then the image packets contain valid RGB or CMYK colors. If PseudoClass then the image has a colormap referenced by pixel's index member.
tile_info RectangleInfo Describes a tile within an image. For example, if your images is 640x480 you may only want 320x256 with an offset of +128+64. It is used for raw formats such as RGB and CMYK as well as for TIFF.
timer TimerInfo Support for measuring actual (user + system) and elapsed execution time.
total_colors unsigned long The number of colors in the image after QuantizeImage(), or QuantizeImages() if the verbose flag was set before the call. Calculated by GetNumberColors().
units ResolutionType Units of image resolution
x_resolution double Horizontal resolution of the image
y_resolution double Vertical resolution of the image

ImageInfo

The ImageInfo structure is used to supply option information to the functions AllocateImage(), AnimateImages(), BlobToImage(), CloneAnnotateInfo(), DisplayImages(), GetAnnotateInfo(), ImageToBlob(), PingImage(), ReadImage(), ReadImages(), and, WriteImage(). These functions update information in ImageInfo to reflect attributes of the current image.

Use CloneImageInfo() to duplicate an existing ImageInfo structure or allocate a new one. Use DestroyImageInfo() to deallocate memory associated with an ImageInfo structure. Use GetImageInfo() to initialize an existing ImageInfo structure. Use SetImageInfo() to set image type information in the ImageInfo structure based on an existing image.

The members of the ImageInfo structure are shown in the following table:

ImageInfo Structure Members
Member Type Description
adjoin unsigned int Join images into a single multi-image file.
antialias unsigned int Control antialiasing of rendered Postscript and Postscript or TrueType fonts. Enabled by default.
background_color PixelPacket Image background color.
border_color PixelPacket Image border color.
colorspace ColorspaceType Image pixel interpretation.If the colorspace is RGB the pixels are red, green, blue. If matte is true, then red, green, blue, and index. If it is CMYK, the pixels are cyan, yellow, magenta, black. Otherwise the colorspace is ignored.
compression CompressionType Image compresion type. The default is the compression type of the specified image file.
delay char * 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.
density char * 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 page.
depth unsigned int Image depth (8 or 16). QuantumLeap must be defined before a depth of 16 is valid.
dispose char * GIF disposal method. This option is used to control how successive frames are rendered (how the preceding frame is disposed of) when creating a GIF animation.
dither unsigned int 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 colors or monochrome option must be set for this option to take effect.
file FILE * Stdio stream to read image from or write image to. If set, ImageMagick will read from or write to the stream rather than opening a file. Used by ReadImage() and WriteImage(). The stream is closed when the operation completes.
filename char [MaxTextExtent] Image file name to read or write.
fill PixelPacket Drawing object fill color.
font char * 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").
fuzz int 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.
interlace 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.
iterations char * Number of iterations to loop an animation (e.g. Netscape loop extension) for.
linewidth unsigned int Line width for drawing lines, circles, ellipses, etc.
magick char [MaxTextExtent] Image encoding format (e.g. "GIF").
matte_color PixelPacket Image matte (transparent) color.
monochrome unsigned int Transform the image to black and white.
page char * Equivalent size of Postscript page.
ping unsigned int Set to True to read enough of the image to determine the image columns, rows, and filesize. The columns, rows, and size attributes are valid after invoking ReadImage() while ping is set. The image data is not valid after calling ReadImage() if ping is set.
pointsize double Text rendering font point size.
preview_type PreviewType Image manipulation preview option. Used by 'display'.
quality unsigned int JPEG/MIFF/PNG compression level (default 75).
server_name char * X11 display to display to obtain fonts from, or to capture image from.
size char * 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.
stroke PixelPacket Drawing object outline color.
subimage unsigned int Subimage of an image sequence.
subrange unsigned int Number of images relative to the base image.
texture char * Image filename to use as background texture.
tile char * Tile name.
units ResolutionType Units of image resolution.
verbose unsigned int Print detailed information about the image if True.
view char * FlashPix viewing parameters.

ImageType

ImageType indicates the type classification of the image.

ImageType
Enumeration Description
UndefinedType Unset value.
BilevelType Monochrome image
GrayscaleType Grayscale image
PaletteType Indexed color (palette) image
PaletteMatteType Indexed color (palette) image with opacity
TrueColorType Truecolor image
TrueColorMatteType Truecolor image with opacity
ColorSeparationType Cyan/Yellow/Magenta/Black (CYMK) image

IndexPacket

IndexPacket is the type used for a colormap index. An array of type IndexPacket is used to represent an image in PseudoClass type. Currently supported IndexPacket underlying types are 'unsigned char' and 'unsigned short'. The type is selected at build time according to the QuantumDepth setting.

InterlaceType

InterlaceType specifies the ordering of the red, green, and blue pixel information in the image. Interlacing is usually used to make image information available to the user faster by taking advantage of the space vs time tradeoff. For example, interlacing allows images on the Web to be recognizable sooner and satellite images to accumulate/render with image resolution increasing over time.

Use LineInterlace or PlaneInterlace to create an interlaced GIF or progressive JPEG image.

InterlaceType
Enumeration Description
UndefinedInterlace Unset value.
NoInterlace Don't interlace image (RGBRGBRGBRGBRGBRGB...)
LineInterlace Use scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...)
PlaneInterlace Use plane interlacing (RRRRRR...GGGGGG...BBBBBB...)
PartitionInterlace Similar to plane interlaing except that the different planes are saved to individual files (e.g. image.R, image.G, and image.B)

LayerType

LayerType is used as an argument when doing color separations. Use LayerType when extracting a layer from an image. MatteLayer is useful for extracting the opacity values from an image.

LayerType
Enumeration Description
UndefinedLayer Unset value.
RedLayer Select red layer
GreenLayer Select green layer
BlueLayer Select blue layer
MatteLayer Select matte (opacity values) layer

MagickInfo

The MagickInfo structure is used by GraphicsMagick to register support for an image format. The MagickInfo structure is allocated with default parameters by calling SetMagickInfo(). Image formats are registered by calling RegisterMagickInfo() which adds the initial structure to a linked list (at which point it is owned by the list). A pointer to the structure describing a format may be obtained by calling GetMagickInfo(). Pass the argument NULL to obtain the first member of this list. A human-readable list of registered image formats may be printed to a file descriptor by calling ListMagickInfo().

Support for formats may be provided as a module which is part of the GraphicsMagick library, provided by a module which is loaded dynamically at run-time, or directly by the linked program. Users of GraphicsMagick will normally want to create a loadable-module, or support encode/decode of an image format directly from within their program.

Sample Module:

The following shows sample code for a module called "GIF" (gif.c). Note that the names of the Register and Unregister call-back routines are calculated at run-time, and therefore must follow the rigid naming scheme RegisterFORMATImage and UnregisterFORMATImage, respectively, where FORMAT is the upper-cased name of the module file:

/* Read image */
Image *ReadGIFImage(const ImageInfo *image_info)
{
  [ decode the image ... ]
}

/* Write image */
unsigned int WriteGIFImage(const ImageInfo *image_info,Image *image)
{
  [ encode the image ... ]
}

/* Module call-back to register support for formats */
void RegisterGIFImage(void)
{
  MagickInfo *entry;
  entry=SetMagickInfo("GIF");
  entry->decoder=ReadGIFImage;
  entry->encoder=WriteGIFImage;
  entry->description="CompuServe graphics interchange format";
  entry->module="GIF";
  RegisterMagickInfo(entry);

  entry=SetMagickInfo("GIF87");
  entry->decoder=ReadGIFImage;
  entry->encoder=WriteGIFImage;
  entry->adjoin=False;
  entry->description="CompuServe graphics interchange format (version 87a)";
  entry->module="GIF";
  RegisterMagickInfo(entry);
}

/* Module call-back to unregister support for formats */
Export void UnregisterGIFImage(void)
{
  UnregisterMagickInfo("GIF");
  UnregisterMagickInfo("GIF87");
}

Sample Application Code

Image format support provided within the user's application does not need to implement the RegisterFORMATImage and UnregisterFORMATImage call-back routines. Instead, the application takes responsibility for the registration itself. An example follows:

/* Read image */
Image *ReadGIFImage(const ImageInfo *image_info)
{
  [ decode the image ... ]
}
/* Write image */
unsigned int WriteGIFImage(const ImageInfo *image_info,Image *image)
{
  [ encode the image ... ]
}
#include <stdio.h>
int main( void )
{
  struct MagickInfo* info;
  info = SetMagickInfo("GIF");
  if ( info == (MagickInfo*)NULL )
  exit(1);
  info->decoder = ReadGIFImage;
  info->encoder = WriteGIFImage;
  info->adjoin = False;
  info->description = "CompuServe graphics interchange format";
  /* Add MagickInfo structure to list */
  RegisterMagickInfo(info);
  info = GetMagickInfo("GIF");
  [ do something with info ... ]
  ListMagickInfo( stdout );
  return;
}

MagickInfo Structure Definition

The members of the MagickInfo structure are shown in the following table:

MagickInfo Structure Members
Member Type Description
adjoin unsigned int Set to non-zero (True) if this file format supports multi-frame images.
blob_support unsigned int Set to non-zero (True) if the encoder and decoder for this format supports operating on arbitrary BLOBs (rather than only disk files).
data void * User specified data. A way to pass any sort of data structure to the endoder/decoder. To set this, GetMagickInfo() must be called to first obtain a pointer to the registered structure since it can not be set via a RegisterMagickInfo() parameter.
decoder Image *(*decoder) (const ImageInfo *) Function to decode image data and return GraphicsMagick Image.
description char * Long form image format description (e.g. "CompuServe graphics interchange format").
encoder unsigned int (*encoder)(const ImageInfo *, Image *) Function to encode image data with options passed via ImageInfo and image represented by Image.
module char * Name of module (e.g. "GIF") which registered this format. Set to NULL if format is not registered by a module.
name const char * Magick string (e.g. "GIF") which identifies this format.
next MagickInfo Next MagickInfo struct in linked-list. NULL if none.
previous MagickInfo Previous MagickInfo struct in linked-list. NULL if none.
raw unsigned int Image format does not contain size (must be specified in ImageInfo).

MonitorHandler

MonitorHandler is the function type to be used for the progress monitor callback. Its definition is as follows:

typedef unsigned int
  (*MonitorHandler)(const char *text, const magick_int64_t quantum,
    const magick_uint64_t span, ExceptionInfo *exception);

The operation of the monitor handler is described in the following table:

MonitorHandler Parameters
Parameter Type Description
return status unsigned int The progress monitor should normally return True (a non-zero value) if the operation is to continue. If the progress monitor returns false, then the operation is will be aborted. This mechanism allows a user to terminate a process which is taking too long to complete.
text const char * A description of the current operation being performed.
quantum const magick_int64_t A value within the range of 0 to span which indicates the degree of progress.
span const magick_uint64_t The total range that quantum will span.
exception exceptionInfo * If the progress monitor returns False (abort operation), it should also update the structure passed via the exception parameter so that an error message may be reported to the user.

MontageInfo

typedef struct _MontageInfo
{
  char
    *geometry,
    *tile,
    *title,
    *frame,
    *texture,
    *font;

  double
    pointsize;

  unsigned long
    border_width;

  unsigned int
    shadow;

  PixelPacket
    fill,
    stroke,
    background_color,
    border_color,
    matte_color;

  GravityType
    gravity;

  char
    filename[MaxTextExtent];

  unsigned long
    signature;
} MontageInfo;

NoiseType

NoiseType is used as an argument to select the type of noise to be added to the image.

NoiseType
Enumeration Description
UniformNoise Uniform noise
GaussianNoise Gaussian noise
MultiplicativeGaussianNoise Multiplicative Gaussian noise
ImpulseNoise Impulse noise
LaplacianNoise Laplacian noise
PoissonNoise Poisson noise

OrientationType

OrientationType specifies the orientation of the image. Useful for when the image is produced via a different ordinate system, the camera was turned on its side, or the page was scanned sideways.

OrientationType
Enumeration Scanline Direction Frame Direction
UndefinedOrientation Unknown Unknown
TopLeftOrientation Left to right Top to bottom
TopRightOrientation Right to left Top to bottom
BottomRightOrientation Right to left Bottom to top
BottomLeftOrientation Left to right Bottom to top
LeftTopOrientation Top to bottom Left to right
RightTopOrientation Top to bottom Right to left
RightBottomOrientation Bottom to top Right to left
LeftBottomOrientation Bottom to top Left to right

PaintMethod

PaintMethod specifies how pixel colors are to be replaced in the image. It is used to select the pixel-filling algorithm employed.

PaintMethod
Enumeration Description
PointMethod Replace pixel color at point.
ReplaceMethod Replace color for all image pixels matching color at point.
FloodfillMethod Replace color for pixels surrounding point until encountering pixel that fails to match color at point.
FillToBorderMethod Replace color for pixels surrounding point until encountering pixels matching border color.
ResetMethod Replace colors for all pixels in image with pen color.

PixelPacket

The PixelPacket structure is used to represent DirectClass color pixels in GraphicsMagick. If the image is indicated as a PseudoClass image, its DirectClass representation is only valid immediately after calling SyncImage(). If an image is set as PseudoClass and the DirectClass representation is modified, the image should then be set as DirectClass. Use QuantizeImage() to restore the PseudoClass colormap if the DirectClass representation is modified.

The members of the PixelPacket structure are shown in the following table:

PixelPacket Structure Members
Member Type Interpretation
RGBColorspace (3) RGBColorspace + matte(3) CMYKColorspace
red Quantum Red Red Cyan
green Quantum Green Green Magenta
blue Quantum Blue Blue Yellow
opacity Quantum Ignored Opacity Black

Notes:

  1. Quantum is an unsigned short (MaxRGB=65535) if GraphicsMagick is built using -DQuantumDepth=16 Otherwise it is an unsigned char (MaxRGB=255).
  2. SyncImage() may be used to synchronize the DirectClass color pixels to the current PseudoClass colormap.
  3. For pixel representation purposes, all colorspaces are treated like RGBColorspace except for CMYKColorspace.

PointInfo

The PointInfo structure is used by the ChromaticityInfo structure to specify chromaticity point values. This defines the boundaries and gammut (range of included color) of the colorspace.

The members of the PointInfo structure are shown in the following table:

PointInfo Structure Members
Member Type Description
x double X ordinate
y double Y ordinate
z double Z ordinate

ProfileInfo

The ProfileInfo structure is used to represent ICC or IPCT profiles in GraphicsMagick (stored as an opaque BLOB).

The members of the ProfileInfo structure are shown in the following table:

ProfileInfo Structure Members
Member Type Description
length unsigned int Profile length
info unsigned char * Profile data

QuantizeInfo

The QuantizeInfo structure is used to support passing parameters to GraphicsMagick's color quantization (reduction) functions. Color quantization is the process of analyzing one or more images, and calculating a color palette which best approximates the image within a specified colorspace, and then adjusting the image pixels to use the calculated color palette. The maximum number of colors allowed in the color palette may be specified.

Methods Supporting QuantizeInfo
Method Description
GetQuantizeInfo() Allocate new structure with defaults set.
CloneQuantizeInfo() Copy existing structure, allocating new structure in the process.
DestroyQuantizeInfo () Deallocate structure, including any members.
QuantizeImage Analyzes the colors within a reference image and chooses a fixed number of colors to represent the image.
QuantizeImages Analyzes the colors within a set of reference images and chooses a fixed number of colors to represent the set.
QuantizeInfo Structure Members
Member Type Description
colorspace ColorspaceType The colorspace to quantize in. Color reduction, by default, takes place in the RGB color space. 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. The Transparent color space behaves uniquely in that it preserves the matte channel of the image if it exists.
dither unsigned int Set to True (non-zero) to apply Floyd/Steinberg error diffusion to the image. When the size of the color palette is less than the image colors, this trades off spacial resolution for color resolution by dithering to achieve a similar looking image.
measure_error unsigned int Set to True (non-zero) to calculate quantization errors when quantizing the image.
number_colors unsigned int Specify the maximum number of colors in the output image. Must be equal to, or less than MaxRGB, which is determined by the value of QuantumLeap when GraphicsMagick was compiled.
signature unsigned long ???
tree_depth unsigned int Specify the tree depth to use while quantizing. The values zero and one support automatic tree depth determination. The tree depth may be forced via values ranging from two to eight. The ideal tree depth depends on the characteristics of the input image, and may be determined through experimentation.

Quantum

Quantum is the base type ('unsigned char', 'unsigned short', 'unsigned int') used to store a pixel component (e.g. 'R' is one pixel component of an RGB pixel).

QuantumType

QuantumType is used to indicate the source or destination format of entire pixels, or components of pixels ("Quantums") while they are being read, or written to, a pixel cache. The validity of these format specifications depends on whether the Image pixels are in RGB format, RGBA format, or CMYK format. The pixel Quantum size is determined by the Image depth (eight or sixteen bits).

RGB(A) Image Quantums
Enumeration Description
IndexQuantum PseudoColor colormap indices (valid only for image with colormap)
RedQuantum Red pixel Quantum
GreenQuantum Green pixel Quantum
BlueQuantum Blue pixel Quantum
OpacityQuantum Opacity (Alpha) Quantum
CMY(K) Image Quantum
Enumeration Description
CyanQuantum Cyan pixel Quantum
MagentaQuantum Magenta pixel Quantum
YellowQuantum Yellow pixel Quantum
BlackQuantum Black pixel Quantum
Grayscale Image Quantums
Enumeration Description
GrayQuantum Gray pixel
GrayOpacityQuantum Pixel opacity
Entire Pixels (Expressed in Byte Order)
Enumeration Description
RGBQuantum RGB pixel (24 or 48 octets)
RGBAQuantum RGBA pixel (32 or 64 octets)
CMYKQuantum CMYK pixel (32 or 64 octets)

RectangleInfo

The RectangleInfo structure is used to represent positioning information in GraphicsMagick.

The members of the RectangleInfo structure are shown in the following table:

RectangleInfo Structure Members
Member Type Description
width unsigned int Rectangle width
height unsigned int Rectangle height
x int Rectangle horizontal offset
y int Rectangle vertical offset

RegistryType

typedef enum
{
  UndefinedRegistryType,
  ImageRegistryType,
  ImageInfoRegistryType
} RegistryType;

RenderingIntent

Rendering intent is a concept defined by ICC Spec ICC.1:1998-09, "File Format for Color Profiles". GraphicsMagick uses RenderingIntent in order to support ICC Color Profiles.

From the specification: "Rendering intent specifies the style of reproduction to be used during the evaluation of this profile in a sequence of profiles. It applies specifically to that profile in the sequence and not to the entire sequence. Typically, the user or application will set the rendering intent dynamically at runtime or embedding time."

RenderingIntent
Enumeration Description
UndefinedIntent Unset value.
SaturationIntent A rendering intent that specifies the saturation of the pixels in the image is preserved perhaps at the expense of accuracy in hue and lightness.
PerceptualIntent A rendering intent that specifies the full gamut of the image is compressed or expanded to fill the gamut of the destination device. Gray balance is preserved but colorimetric accuracy might not be preserved.
AbsoluteIntent Absolute colorimetric
RelativeIntent Relative colorimetric

ResolutionType

By default, GraphicsMagick defines resolutions in pixels per inch. ResolutionType provides a means to adjust this.

ResolutionType
Enumeration Description
UndefinedResolution Unset value.
PixelsPerInchResolution Density specifications are specified in units of pixels per inch (english units).
PixelsPerCentimeterResolution Density specifications are specified in units of pixels per centimeter (metric units).

ResourceType

typedef enum
{
  UndefinedResource,
  FileResource,
  MemoryResource,
  MapResource,
  DiskResource
} ResourceType;

SegmentInfo

typedef struct _SegmentInfo
{
  double
    x1,
    y1,
    x2,
    y2;
} SegmentInfo;

SignatureInfo

typedef struct _SignatureInfo
{
  unsigned long
    digest[8],
    low_order,
    high_order;

  long
    offset;

  unsigned char
    message[SignatureSize];
} SignatureInfo;

StorageType

typedef enum
{
  CharPixel,
  ShortPixel,
  IntegerPixel,
  LongPixel,
  FloatPixel,
  DoublePixel
} StorageType;

StreamHandler

typedef unsigned int
  (*StreamHandler)(const Image *,const void *,const size_t);

StretchType

typedef enum
{
  NormalStretch,
  UltraCondensedStretch,
  ExtraCondensedStretch,
  CondensedStretch,
  SemiCondensedStretch,
  SemiExpandedStretch,
  ExpandedStretch,
  ExtraExpandedStretch,
  UltraExpandedStretch,
  AnyStretch
} StretchType;

StyleType

typedef enum
{
  NormalStyle,
  ItalicStyle,
  ObliqueStyle,
  AnyStyle
} StyleType;

TypeMetric

typedef struct _TypeMetric
{
  PointInfo
    pixels_per_em;

  double
    ascent,
    descent,
    width,
    height,
    max_advance;

  SegmentInfo
    bounds;

  double
    underline_position,
    underline_thickness;
} TypeMetric;

ViewInfo

ViewInfo represents a handle to a pixel view, which represents a uniquely selectable rectangular region of pixels. The only limit on the number of views is the amount of available memory. Each Image contains a collection of default views (one view per thread) so that the image may be usefully accessed without needing to explicitly allocate pixel views.

typedef void *ViewInfo;

VirtualPixelMethod

typedef enum
{
  UndefinedVirtualPixelMethod,
  ConstantVirtualPixelMethod,
  EdgeVirtualPixelMethod,
  MirrorVirtualPixelMethod,
  TileVirtualPixelMethod
} VirtualPixelMethod;

MagickXResourceInfo

typedef struct _XResourceInfo
{
  XrmDatabase
    resource_database;

  ImageInfo
    *image_info;

  QuantizeInfo
    *quantize_info;

  unsigned long
    colors;

  unsigned int
    close_server,
    backdrop;

  char
    *background_color,
    *border_color;

  char
    *client_name;

  XColormapType
    colormap;

  unsigned int
    border_width,
    color_recovery,
    confirm_exit,
    delay;

  char
    *display_gamma;

  char
    *font,
    *font_name[MaxNumberFonts],
    *foreground_color;

  unsigned int
    display_warnings,
    gamma_correct;

  char
    *icon_geometry;

  unsigned int
    iconic,
    immutable;

  char
    *image_geometry;

  char
    *map_type,
    *matte_color,
    *name;

  unsigned int
    magnify,
    pause;  char
    *pen_colors[MaxNumberPens];

  char
    *text_font,
    *title;

  int
    quantum;

  unsigned int
    update,
    use_pixmap,
    use_shared_memory;

  unsigned long
    undo_cache;

  char
    *visual_type,
    *window_group,
    *window_id,
    *write_filename;

  Image
    *copy_image;

  int
    gravity;

  char
    home_directory[MaxTextExtent];
} XResourceInfo;

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