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

The ClassType enumeration specifies the image storage class. A DirectClass representation of an image is based on an array of PixelPacket structures in RAM and/or in a disk file where color values are stored "directly". A PseudoClass representation of an image is based on an array of IndexPacket values (also in RAM and/or in a disk file) which are the index values to the Image colormap (a small array of PixelPacket values) where the color values corresponding to the pixel at the index are stored.

It is possible for an image to be represented as DirectClass and PseudoClass simultaneously, but only one type may be claimed as the current representation by the Image storage_class member. It is normally assumed that when the Image is set to PseudoClass that the DirectClass representation is up to date but while updating the image, this is often not the case. The DirectClass representation of the image may be updated based on the PseudoClass representation by calling the SyncImage() function.

As a special case, CMYK is represented by the red, green, blue, and opacity members of PixelPacket, and CMYKA is the same except that the IndexPacket values represent Opacity. CMYKA images are described as DirectClass even though the IndexPacket values are used (the image colormap is not valid).

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, such as television, offset printing, and 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 than do distances in RGB space. These color spaces may give better results when reducing the color of 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 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.
MultiplyCompositeOp	The result of composite image × image. This is useful for the creation of drop-shadows.
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
OverlayCompositeOp
CopyCyanCompositeOp	Copy the Cyan channel.
CopyMagentaCompositeOp	Copy the Magenta channel.
CopyYellowCompositeOp	Copy the Yellow channel.
CopyBlackCompositeOp	Copy the Black channel.
DivideCompositeOp
HardLightCompositeOp
ExclusionCompositeOp
ColorDodgeCompositeOp
ColorBurnCompositeOp
SoftLightCompositeOp
LinearBurnCompositeOp
LinearDodgeCompositeOp
LinearLightCompositeOp
VividLightCompositeOp
PinLightCompositeOp
HardMixCompositeOp

CompressionType

CompressionType is used to specify the desired compression type when encoding an image. Be aware that most image types only support a subset of the available compression types. If the specified compression type is incompatible with the image, GraphicsMagick will select a compression type compatible with the image type, which might be no compression at all.

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.
LZMACompression	LZMA - Lempel-Ziv-Markov chain algorithm
JPEG2000Compression	JPEG 2000 - ISO/IEC std 15444-1
JBIG1Compression	JBIG v1 - ISO/IEC std 11544 / ITU-T rec T.82
JBIG2Compression	JBIG v2 - ISO/IEC std 14492 / ITU-T rec T.88
ZSTDCompression	Facebook's Zstandard/Zstd
WebPCompression	Google's WebP

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
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

Some formats, such as TIFF and DPX, allow storing data in multiple "endian" orders and EndianType allows controlling that. With MSB endian and accessing memory bytes with increasing offset, the most significant byte is encountered first, while with LSB endian, the least significant byte is encountered first.

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

Warnings and errors are represented by integer numbers (declared as an ExceptionType enumeration) with the range of warnings starting with WarningException, the range of errors starting with ErrorException, and the range of fatal errors starting with FatalErrorException.

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 defaults to using the LanczosFilter, which has been proven to provide the best results for most images in a reasonable amount of time. Other filter types, such as the TriangleFilter, may execute much faster but may show artifacts when the image is resized 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, such as text or an image, within a bounding region. 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

LogEventType

LogEventType specifies the log event type to match one or more log areas. Although defined as an enum type, the values are based on unsigned integer flags value with one mask bit set, more than one mask bit set, or all of the assigned mask bits set. Values are boolean ORed together to represent multiple event types.

LogEventType
Enumeration	Description
UndefinedEventMask	No events specified
NoEventsMask	No events specified
ConfigureEventMask	Configuration event (related to initialization or shutdown)
AnnotateEventMask	Annotation event (text drawing)
RenderEventMask	Rendering event (vector drawing)
TransformEventMask	Image transformation event (e.g. cropping)
LocaleEventMask	Locale event (internationalization)
CoderEventMask	Coder event (file decode or encode)
X11EventMask	X11 event (event related to use of X11)
CacheEventMask	Pixel cache event (pixel storage in memory or on disk)
BlobEventMask	Blob event (I/O to/from memory or a file)
DeprecateEventMask	Deprecation event (use of a function which will be removed)
UserEventMask	User event (event allowed for the user, not otherwise used)
ResourceEventMask	Resource event (resource limit assignment, allocation/deallocation)
TemporaryFileEventMask	Temporary file event (temporary file created or removed)
ExceptionEventMask	Exception event (a warning or error was reported into ExceptionInfo)
OptionEventMask	Option event (something related to a user provided option)
InformationEventMask	Information event
WarningEventMask	Warning event (a warning was reported into ExceptionInfo)
ErrorEventMask	Error event (an error was reported into ExceptionInfo)
FatalErrorEventMask	Fatal error event (a fatal error was reported into ExceptionInfo)
AllEventsMask	All events (matches any/all events)

LogMethod

LogMethod is a call-back function type in the form:

typedef void (*LogMethod)(const ExceptionType type,const char *text)

LogOutputType

LogOutputType specifies how/where logging ("tracing") output is to be directed.

LogOutputType
Enumeration	Description
DisabledOutput	Reporting disabled
UndefinedOutput	Reporting disabled
StdoutOutput	Log to stdout in "human readable" format
StderrOutput	Log to stderr in "human readable" format
XMLFileOutput	Log to a file in an XML format
TXTFileOutput	Log to a file in a text format
Win32DebugOutput	Windows, Output events to the application/system debugger.
Win32EventlogOutput	Windows, Output events to the Application event log.
MethodOutput	Log by calling registered C-language callback function

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 long	Image width
compression	CompressionType	Image compresion type. The default is the compression type of the specified image file.
delay	unsigned long	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	DisposeType	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.
endian	EndianType	The byte order to use when writing images.
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	double	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.
gravity	GravityType	Positioning of the image within a bounding region.
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 long	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 long	Base image width (before transformations)
magick_filename	char [MaxTextExtent]	Base image filename (before transformations)
magick_rows	unsigned long	Base image height (before transformations)
matte	MagickBool	If true, 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	long	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 long	Image height
scene	unsigned long	Image frame scene number.
start_loop	long	Animation frame number to start looping at.
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 the 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	MagickBool	Join images into a single multi-image file.
antialias	MagickBool	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.
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 long	Image depth (8 or 16). QuantumLeap must be defined before a depth of 16 is valid.
dither	MagickBool	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.
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	double	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.
magick	char [MaxTextExtent]	Image encoding format (e.g. "GIF").
matte_color	PixelPacket	Image matte (transparent) color.
monochrome	MagickBool	Transform the image to black and white.
page	char *	Equivalent size of Postscript page.
pen	PixelPacket	Drawing object stroke or fill color.
pointsize	double	Text rendering font point size.
quality	unsigned long	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, such as Photo CD, JBIG, or JPEG.
subimage	unsigned long	Subimage of an image sequence.
subrange	unsigned long	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
GrayscaleMatteType	Grayscale image with opacity
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
ColorSeparationMatteType	Cyan/Yellow/Magenta/Black (CYMK) image with opacity

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', 'unsigned short', and 'unsigned int'. The type is selected at build time according to the QuantumDepth setting.

typedef Quantum IndexPacket;

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 callback 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 callback 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	MagickBool	Set to non-zero (True) if this file format supports multi-frame images.
blob_support	MagickBool	Set to non-zero (True) if the encoder and decoder for this format supports operating on arbitrary BLOBs (rather than only disk files).
client_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.
coder_class	CoderClass	Image format coder stability level.
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.
note	const char *	Usage note for users.
previous	MagickInfo	Previous MagickInfo struct in linked-list. NULL if none.
stealth	MagickBook	Image format should not appear appear in format listings.
raw	MagickBool	Image format does not contain size (must be specified in ImageInfo).
version	const char *	Version of the support library used for the format.

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);

A MonitorHandler should normally return True (a non-zero value) if the operation can continue. If it returns False, then the operation will be aborted. This mechanism enables a user to terminate a process that is taking too long to complete.

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

MonitorHandler Parameters
Parameter	Type	Description
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
RandomNoise	Random noise (uniform distribution)
UndefinedNoise	Undefined 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 assured to be valid immediately after calling SyncImage(), although it is usually already valid and the convention is to assure that the DirectClass representation is updated. 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
Member	Type	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:

Quantum is an unsigned short (MaxRGB=65535) if GraphicsMagick is built using -DQuantumDepth=16 Otherwise it is an unsigned char (MaxRGB=255).

SyncImage() may be used to synchronize the DirectClass color pixels to the current PseudoClass colormap.

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

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	size_t	Profile length
name	char *	Profile name
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 long	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 used to store a pixel component, such as the 'R' in an RGB pixel. It can be defined as either an 'unsigned char', 'unsigned short', or an 'unsigned int'.

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, which can be eight, sixteen, or thirty-two 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 long	Rectangle width
height	unsigned long	Rectangle height
x	long	Rectangle horizontal offset
y	long	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

Resource limits constrain the system resources that a GraphicsMagick process may consume, or that individual decode/encode and/or image processing operations may consume. If a resource is expended and another resource may be substituted (such as RAM memory vs an on-disk temporary file), then the alternative resource is used until it is also expended. When a resource limit is exceeded and there is no more alternative resource available, then a hard error is reported for the operation being performed.

Global limits may be applied for the Pixel Cache total disk space (Gigabytes), the Pixel Cache number of simultaneous open files (Files), the Pixel Cache total file memory-mapping (Megabytes), the maximum heap memory allocations (Megabytes), the maximum number of pixels in a single image (Pixels), the maximum number of worker threads, the maximum pixel width of an image (Pixels), the maximum pixel height of an image (Pixels), and the maximum amount of uncompressed file data which may be read while decoding.

Normally these limits should be set before using GraphicsMagick to perform other operations. Environment variables are available which may also set these properties when GraphicsMagick is initialized.

ResourceType
Enumeration	Description
UndefinedResource	Undefined value
DiskResource	Pixel cache total disk space (Gigabytes)
FileResource	Pixel cache number of open files (Files)
MapResource	Pixel cache total file memory-mapping (Megabytes)
MemoryResource	Maximum heap memory (e.g. malloc) allocations (Megabytes)
PixelsResource	Maximum number of pixels in a single image (Pixels)
ThreadsResource	Maximum number of worker threads
WidthResource	Maximum pixel width of an image (Pixels)
HeightResource	Maximum pixel height of an image (Pixels)
ReadResource	Maximum amount of uncompressed file data which may be read while decoding

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

The VirtualPixelMethod enumeration describes how the pixel cache APIs fill requested pixel regions which are outside of the image. Returned pixels must be initialized to some value. The edge of the image represents a "disconnect" but convolutions and other filters need mathematical continuity while computing their results or else the computed edges of the image would be distorted.

VirtualPixelMethod Enumeration Values
Enumeration	Description
UndefinedVirtualPixelMethod	Value was not specified
ConstantVirtualPixelMethod	Use the image background color
EdgeVirtualPixelMethod	Extend the edge pixel toward infinity (default)
MirrorVirtualPixelMethod	Mirror the image
TileVirtualPixelMethod	Tile the image

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;