GraphicsMagick

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# 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
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

# 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;

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