Magick::Image Class

Quick Contents

• BLOBs
• Constructors
• Image Manipulation Methods
• Image Attributes
• Raw Image Pixel Access

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

#include <Magick++.h>
#include <iostream>
using namespace std;
using namespace Magick;
int main(int argc,char **argv)
{
  try {
    // Create an image object and read an image
    Image image( "girl.gif" );

    // Crop the image to specified size
    // (Geometry implicitly initialized by char *)
    image.crop("100x100+100+100" );

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

1. Read master image.
2. Assign master image to second image.
3. Zoom second image to the size 640x480.
4. Assign master image to a third image.
5. Zoom third image to the size 800x600.
6. Write the second image to a file.
7. Write the third image to a file.

#include <Magick++.h>
#include <iostream>
using namespace std;
using namespace Magick;
int main(int argc,char **argv)
{
    Image master("horse.jpg");
    Image second = master;
    second.zoom("640x480");
    Image third = master;
    third.zoom("800x600");
    second.write("horse640x480.jpg");
    third.write("horse800x600.jpg");
    return 0;
}

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

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

    image.quantizeColorSpace( GRAYColorspace );
    image.quantize( options );

prior to writing the image.

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

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

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

    [ Use BLOB data (in JPEG format) here ]

    return 0;
}

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

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

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

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

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

The operations supported by Image are shown in the following table:
 

Image Image Manipulation Methods

Method	Signature(s)	Description
addNoise	NoiseType noiseType_	Add noise to image with specified noise type.
annotate	const std::string &text_, const Geometry &location_	Annotate using specified text, and placement location
	string text_, const Geometry &boundingArea_, GravityType gravity_	Annotate using specified text, bounding area, and placement gravity. If boundingArea_ is invalid, then bounding area is entire image.
	const std::string &text_, const Geometry &boundingArea_, GravityType gravity_, double degrees_,	Annotate with text using specified text, bounding area, placement gravity, and rotation. If boundingArea_ is invalid, then bounding area is entire image.
	const std::string &text_, GravityType gravity_	Annotate with text (bounding area is entire image) and placement gravity.
blur	const double radius_ = 1, const double sigma_ = 0.5	Blur image. The radius_ parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel.  The sigma_ parameter specifies the standard deviation of the Laplacian, in pixels.
border	const Geometry &geometry_ = "6x6+0+0"	Border image (add border to image).  The color of the border is specified by the borderColor attribute.
channel	ChannelType layer_	Extract channel from image. Use this option to extract a particular channel from  the image.  MatteChannel  for  example, is useful for extracting the opacity values from an image.
charcoal	const double radius_ = 1, const double sigma_ = 0.5	Charcoal effect image (looks like charcoal sketch). The radius_ parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel.  The sigma_ parameter specifies the standard deviation of the Laplacian, in pixels.
chop	const Geometry &geometry_	Chop image (remove vertical or horizontal subregion of image)
colorize	const unsigned int opacityRed_, const unsigned int opacityGreen_, const unsigned int opacityBlue_, const Color &penColor_	Colorize image with pen color, using specified percent opacity for red, green, and blue quantums.
	const unsigned int opacity_, const Color &penColor_	Colorize image with pen color, using specified percent opacity.
comment	const string &comment_	Comment image (add comment string to image).  By default, each image is commented with its file name. Use  this  method to  assign a specific comment to the image.  Optionally you can include the image filename, type, width, height, or other  image  attributes by embedding special format characters.
composite	const Image &compositeImage_, int xOffset_, int yOffset_, CompositeOperator compose_ = InCompositeOp	Compose an image onto the current image at offset specified by xOffset_, yOffset_ using the composition algorithm specified by compose_.
	const Image &compositeImage_, const Geometry &offset_, CompositeOperator compose_ = InCompositeOp	Compose an image onto the current image at offset specified by offset_ using the composition algorithm specified by compose_.
	const Image &compositeImage_, GravityType gravity_, CompositeOperator compose_ = InCompositeOp	Compose an image onto the current image with placement specified by gravity_ using the composition algorithm specified by compose_.
contrast	unsigned int sharpen_	Contrast image (enhance intensity differences in image)
convolve	unsigned int order_, const double *kernel_	Convolve image.  Applies a user-specfied convolution to the image. The order_ parameter represents the number of columns and rows in the filter kernel, and kernel_ is a two-dimensional array of doubles representing the convolution kernel to apply.
crop	const Geometry &geometry_	Crop image (subregion of original image)
cycleColormap	int amount_	Cycle image colormap
despeckle	void	Despeckle image (reduce speckle noise)
display	void	Display image on screen. Caution: if an image format is is not compatable with the display visual (e.g. JPEG on a colormapped display) then the original image will be altered. Use a copy of the original if this is a problem.
draw	const Drawable &drawable_	Draw shape or text on image.
	const std::list<Drawable> &drawable_	Draw shapes or text on image using a set of Drawable objects contained in an STL list. Use of this method improves drawing performance and allows batching draw objects together in a list for repeated use.
edge	unsigned int order_	Edge image (hilight edges in image)
emboss	const double radius_ = 1, const double sigma_ = 0.5	Emboss image (hilight edges with 3D effect). The radius_ parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel.  The sigma_ parameter specifies the standard deviation of the Laplacian, in pixels.
enhance	void	Enhance image (minimize noise)
equalize	void	Equalize image (histogram equalization)
erase	void	Set all image pixels to the current background color.
flip	void	Flip image (reflect each scanline in the vertical direction)
floodFill- Color	unsigned int x_, unsigned int y_, const Color &fillColor_	Flood-fill color across pixels that match the color of the target pixel and are neighbors of the target pixel. Uses current fuzz setting when determining color match.
	const Geometry &point_, const Color &fillColor_
	unsigned int x_, unsigned int y_, const Color &fillColor_, const Color &borderColor_	Flood-fill color across pixels starting at target-pixel and stopping at pixels matching specified border color. Uses current fuzz setting when determining color match.
	const Geometry &point_, const Color &fillColor_, const Color &borderColor_
floodFill- Texture	unsigned int x_, unsigned int y_,  const Image &texture_	Flood-fill texture across pixels that match the color of the target pixel and are neighbors of the target pixel. Uses current fuzz setting when determining color match.
	const Geometry &point_, const Image &texture_
	unsigned int x_, unsigned int y_, const Image &texture_, const Color &borderColor_	Flood-fill texture across pixels starting at target-pixel and stopping at pixels matching specified border color. Uses current fuzz setting when determining color match.
	const Geometry &point_, const Image &texture_, const Color &borderColor_
flop	void	Flop image (reflect each scanline in the horizontal direction)
frame	const Geometry &geometry_ = "25x25+6+6"	Add decorative frame around image
	unsigned int width_, unsigned int height_, int x_, int y_, int innerBevel_ = 0, int outerBevel_ = 0
gamma	double gamma_	Gamma correct image (uniform red, green, and blue correction).
	double gammaRed_, double gammaGreen_, double gammaBlue_	Gamma correct red, green, and blue channels of image.
gaussianBlur	double width_, double sigma_	Gaussian blur image. The number of neighbor pixels to be included in the convolution mask is specified by 'width_'.  For example, a width of one gives a (standard) 3x3 convolution mask. The standard deviation of the gaussian bell curve is specified by 'sigma_'.
implode	double factor_	Implode image (special effect)
label	const string &label_	Assign a label to an image. Use this option to  assign  a  specific label to the image. Optionally you can include the image filename, type, width, height, or scene number in the label by embedding  special format characters. If the first character of string is @, the image label is read from a file titled by the remaining characters in the string. When converting to Postscript, use this  option to specify a header string to print above the image.
magnify	void	Magnify image by integral size
map	const Image &mapImage_ , bool dither_ = false	Remap image colors with closest color from reference image. Set dither_ to true in to apply Floyd/Steinberg error diffusion to the image. By default, color reduction chooses an optimal  set  of colors that best represent the original image. Alternatively, you can  choose  a  particular  set  of colors  from  an image file with this option.
matteFloodfill	const Color &target_, unsigned int matte_, int x_, int y_, PaintMethod method_	Floodfill designated area with a matte value
medianFilter	unsigned int radius_	Filter image by replacing each pixel component with the median color in a circular neighborhood
minify	void	Reduce image by integral size
modifyImage	void	Prepare to update image. Ensures that there is only one reference to the underlying image so that the underlying image may be safely modified without effecting previous generations of the image. Copies the underlying image to a new image if necessary.
modulate	double brightness_, double saturation_, double hue_	Modulate percent hue, saturation, and brightness of an image
negate	bool grayscale_ = false	Negate colors in image.  Replace every pixel with its complementary color (white becomes black, yellow becomes blue, etc.).  Set grayscale to only negate grayscale values in image.
normalize	void	Normalize image (increase contrast by normalizing the pixel values to span the full range of color values).
oilPaint	unsigned int radius_ = 3	Oilpaint image (image looks like oil painting)
opaque	const Color &opaqueColor_, const Color &penColor_	Change color of pixels matching opaqueColor_ to specified penColor_.
ping	const std::string &imageSpec_	Ping is similar to read except only enough of the image is read to determine the image columns, rows, and filesize.  The columns, rows, and fileSize attributes are valid after invoking ping.  The image data is not valid after calling ping.
quantize	bool measureError_ = false	Quantize image (reduce number of colors). Set measureError_ to true in order to calculate error attributes.
raise	const Geometry &geometry_ = "6x6+0+0",  bool raisedFlag_ =  false	Raise image (lighten or darken the edges of an image to give a 3-D raised or lowered effect)
read	const string &imageSpec_	Read image into current object
	const Geometry &size_, const std::string &imageSpec_	Read image of specified size into current object. This form is useful for images that do not specifiy their size or to specify a size hint for decoding an image. For example, when reading a Photo CD, JBIG, or JPEG image, a size request causes the library to return an image which is the next resolution greater or equal to the specified size. This may result in memory and time savings.
	const Blob &blob_	Read encoded image of specified size from an in-memory BLOB into current object. Depending on the method arguments, the Blob size, depth, and format may also be specified. Some image formats require that size be specified. The default ImageMagick uses for depth depends on its Quantum size (8 or 16).  If ImageMagick's Quantum size does not match that of the image, the depth may need to be specified. ImageMagick can usually automatically detect the image's format. When a format can't be automatically detected, the format must be specified.
	const Blob &blob_, const Geometry &size_
	const Blob &blob_, const Geometry &size_, unsigned int depth_
	const Blob &blob_, const Geometry &size_, unsigned short depth_, const string &magick_
	const Blob &blob_, const Geometry &size_, const string &magick_
	const unsigned int width_, const unsigned int height_, std::string map_, const StorageType type_, const void *pixels_	Read image based on an array of image pixels. The pixel data must be in scanline order top-to-bottom. The data can be character, short int, integer, float, or double. Float and double require the pixels to be normalized [0..1]. The other types are [0..MaxRGB].  For example, to create a 640x480 image from unsigned red-green-blue character data, use   image.read( 640, 480, "RGB", 0, pixels ); The parameters are as follows:   width_ Width in pixels of the image. height_ Height in pixels of the image. map_ This character string can be any combination or order of R = red, G = green, B = blue, A = alpha, C = cyan, Y = yellow M = magenta, and K = black. The ordering reflects the order of the pixels in the supplied pixel array. type_ Pixel storage type (CharPixel, ShortPixel, IntegerPixel, FloatPixel, or DoublePixel) pixels_ This array of values contain the pixel components as defined by the map_ and type_ parameters. The length of the arrays must equal the area specified by the width_ and height_ values and type_ parameters.
reduceNoise	void	Reduce noise in image using a noise peak elimination filter.
	unsigned int order_
roll	int columns_, int rows_	Roll image (rolls image vertically and horizontally) by specified number of columnms and rows)
rotate	double degrees_	Rotate image counter-clockwise by specified number of degrees.
sample	const Geometry &geometry_	Resize image by using pixel sampling algorithm
scale	const Geometry &geometry_	Resize image by using simple ratio algorithm
segment	double clusterThreshold_ = 1.0, double smoothingThreshold_ = 1.5	Segment (coalesce similar image components) by analyzing the histograms of the color components and identifying units that are homogeneous with the fuzzy c-means technique. Also uses quantizeColorSpace and verbose image attributes. Specify clusterThreshold_, as the number  of  pixels  each cluster  must exceed the cluster threshold to be considered valid. SmoothingThreshold_ eliminates noise in the  second derivative of the histogram. As the value is  increased, you can  expect  a  smoother second derivative.  The default is 1.5.
shade	double azimuth_ = 30, double elevation_ = 30, bool colorShading_ = false	Shade image using distant light source. Specify azimuth_ and elevation_ as the  position  of  the light source. By default, the shading results as a grayscale image.. Set colorShading_ to true to shade the red, green, and blue components of the image.
sharpen	const double radius_ = 1, const double sigma_ = 0.5	Sharpen pixels in image.  The radius_ parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel.  The sigma_ parameter specifies the standard deviation of the Laplacian, in pixels.
shear	double xShearAngle_, double yShearAngle_	Shear image (create parallelogram by sliding image by X or Y axis).  Shearing slides one edge of an image along the X  or  Y axis,  creating  a parallelogram.  An X direction shear slides an edge along the X axis, while  a  Y  direction shear  slides  an edge along the Y axis.  The amount of the shear is controlled by a shear angle.  For X direction  shears,  x  degrees is measured relative to the Y axis, and similarly, for Y direction shears  y  degrees is measured relative to the X axis. Empty triangles left over from shearing the  image  are filled  with  the  color  defined as borderColor.
solarize	double factor_ = 50.0	Solarize image (similar to effect seen when exposing a photographic film to light during the development process)
spread	unsigned int amount_ = 3	Spread pixels randomly within image by specified amount
stegano	const Image &watermark_	Add a digital watermark to the image (based on second image)
stereo	const Image &rightImage_	Create an image which appears in stereo when viewed with red-blue glasses (Red image on left, blue on right)
swirl	double degrees_	Swirl image (image pixels are rotated by degrees)
texture	const Image &texture_	Layer a texture on pixels matching image background color.
threshold	double threshold_	Threshold image
transform	const Geometry &imageGeometry_	Transform image based on image and crop geometries. Crop geometry is optional.
	const Geometry &imageGeometry_, const Geometry &cropGeometry_
transparent	const Color &color_	Add matte image to image, setting pixels matching color to transparent.
trim	void	Trim edges that are the background color from the image.
unsharpmask	double radius_, double sigma_, double amount_, double threshold_	Replace image with a sharpened version of the original image using the unsharp mask algorithm. The radius_ parameter specifies the radius of the Gaussian, in pixels, not counting the center pixel. The sigma_ parameter specifies the standard deviation of the Gaussian, in pixels. The amount_ parameter specifies the percentage of the difference between the original and the blur image that is added back into the original. The threshold_ parameter specifies the threshold in pixels needed to apply the diffence amount.
wave	double amplitude_ = 25.0, double wavelength_ = 150.0	Alter an image along a sine wave.
write	const string &imageSpec_	Write image to a file using filename imageSpec_. Caution: if an image format is selected which is capable of supporting fewer colors than the original image or quantization has been requested, the original image will be quantized to fewer colors. Use a copy of the original if this is a problem.
	Blob *blob_	Write image to a in-memory BLOB stored in blob_. The magick_ parameter specifies the image format to write (defaults to magick ). The depth_ parameter species the image depth (defaults to depth). Caution: if an image format is selected which is capable of supporting fewer colors than the original image or quantization has been requested, the original image will be quantized to fewer colors. Use a copy of the original if this is a problem.
	Blob *blob_, std::string &magick_
	Blob *blob_, std::string &magick_, unsigned int depth_
	const int x_, const int y_, const unsigned int columns_, const unsigned int rows_, const std::string &map_, const StorageType type_, void *pixels_	Write pixel data into a buffer you supply. The data is saved either as char, short int, integer, float or double format in the order specified by the type_ parameter. For example, we want to extract scanline 1 of a 640x480 image as character data in red-green-blue order:   image.write(0,0,640,1,"RGB",0,pixels); The parameters are as follows:   x_ Horizontal ordinate of left-most coordinate of region to extract. y_ Vertical ordinate of top-most coordinate of region to extract. columns_ Width in pixels of the region to extract. rows_ Height in pixels of the region to extract. map_ This character string can be any combination or order of R = red, G = green, B = blue, A = alpha, C = cyan, Y = yellow, M = magenta, and K = black. The ordering reflects the order of the pixels in the supplied pixel array. type_ Pixel storage type (CharPixel, ShortPixel, IntegerPixel, FloatPixel, or DoublePixel) pixels_ This array of values contain the pixel components as defined by the map_ and type_ parameters. The length of the arrays must equal the area specified by the width_ and height_ values and type_ parameters.
zoom	const Geometry &geometry_	Zoom image to specified size.

The supported image attributes and the method arguments required to obtain them are shown in the following table:
 

Image Image Attributes

Attribute	Type	Get Signature	Set Signature	Description
adjoin	bool	void	bool flag_	Join images into a single multi-image file.
antiAlias	bool	void	bool flag_	Control antialiasing of rendered Postscript and Postscript or TrueType fonts. Enabled by default.
animation- Delay	unsigned int (0 to 65535)	void	unsigned int delay_	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.
animation- Iterations	unsigned int	void	unsigned int iterations_	Number of iterations to loop an animation (e.g. Netscape loop extension) for.
background- Color	Color	void	const Color &color_	Image background color
background- Texture	string	void	const string &texture_	Image file name to use as the background texture. Does not modify image pixels.
baseColumns	unsigned int	void		Base image width (before transformations)
baseFilename	string	void		Base image filename (before transformations)
baseRows	unsigned int	void		Base image height (before transformations)
borderColor	Color	void	const Color &color_	Image border color
boxColor	Color	void	const Color &boxColor_	Base color that annotation text is rendered on.
cacheThreshold	unsigned int		unsigned int	Pixel cache threshold in megabytes with default value 80MB. Once this threshold is exceeded, all subsequent pixels cach operations are to/from disk. This is a static method and the attribute it sets is shared by all Image objects.
chroma- BluePrimary	float x & y	float *x_, float *y_	float x_, float y_	Chromaticity blue primary point (e.g. x=0.15, y=0.06)
chroma- GreenPrimary	float x & y	float *x_, float *y_	float x_, float y_	Chromaticity green primary point (e.g. x=0.3, y=0.6)
chroma- RedPrimary	float x & y	float *x_, float *y_	float x_, float y_	Chromaticity red primary point (e.g. x=0.64, y=0.33)
chroma- WhitePoint	float x & y	float *x_, float *y_	float x_, float y_	Chromaticity white point (e.g. x=0.3127, y=0.329)
classType	ClassType	void	ClassType class_	Image storage class.  Note that conversion from a DirectClass image to a PseudoClass image may result in a loss of color due to the limited size of the palette (256 or 65535 colors).
colorFuzz	double	void	double fuzz_	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.
colorMap	Color	unsigned int index_	unsigned int index_, const Color &color_	Color at color-pallet index.
colorSpace	ColorspaceType colorSpace_	void	ColorspaceType colorSpace_	The colorspace (e.g. CMYK) used to represent the image pixel colors. Image pixels are always stored as RGB(A) except for the case of CMY(K).
columns	unsigned int	void		Image width
comment	string	void		Image comment
compress- Type	CompressionType	void	CompressionType compressType_	Image compresion type. The default is the compression type of the specified image file.
density	Geometry  (default 72x72)	void	const Geometry &density_	Vertical and horizontal resolution in pixels of the image. This option specifies an image density when decoding a Postscript or Portable Document page. Often used with psPageSize.
depth	unsigned int (8 or 16)	void	unsigned int depth_	Image depth. Used to specify the bit depth when reading or writing  raw images. Defaults to the quantum depth that ImageMagick is compiled with.
directory	string	void		Tile names from within an image montage
fileName	string	void	const string &fileName_	Image file name.
fileSize	unsigned int	void		Number of bytes of the image on disk
fillColor	Color	void	const Color &fillColor_	Color to use when filling drawn objects
filterType	FilterTypes	void	FilterTypes filterType_	Filter to use when resizing image. The reduction filter employed has a sigificant effect on the time required to resize an image and the resulting quality. The default filter is Lanczos which has been shown to produce high quality results when reducing most images.
font	string	void	const string &font_	Text rendering font. If the font is a fully qualified X server font name, the font is obtained from an X  server. To use a TrueType font, precede the TrueType filename with an @. Otherwise, specify  a  Postscript font name (e.g. "helvetica").
fontPointsize	unsigned int	void	unsigned int pointSize_	Text rendering font point size
format	string	void		Long form image format description.
gamma	double (typical range 0.8 to 2.3)	void		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	Geometry	void		Preferred size of the image when encoding.
gifDispose- Method	unsigned int { 0 = Disposal not specified, 1 = Do not dispose of graphic, 3 = Overwrite graphic with background color, 4 = Overwrite graphic with previous graphic. }	void	unsigned int disposeMethod_	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.
iccColorProfile	Blob	void	const Blob &colorProfile_	ICC color profile. Supplied via a Blob since Magick++/ and ImageMagick do not currently support formating this data structure directly.  Specifications are available from the International Color Consortium for the format of ICC color profiles.
interlace- Type	InterlaceType	void	InterlaceType interlace_	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.
iptcProfile	Blob	void	const Blob& iptcProfile_	IPTC profile. Supplied via a Blob since Magick++ and ImageMagick do not currently  support formating this data structure directly. Specifications are available from the International Press Telecommunications Council for IPTC profiles.
label	string	void	const string &label_	Image label
magick	string	void	const string &magick_	Get image format (e.g. "GIF")
matte	bool	void	bool matteFlag_	True if the image has transparency. If set True, store matte channel if  the image has one otherwise create an opaque one.
matteColor	Color	void	const Color &matteColor_	Image matte (transparent) color
meanError- PerPixel	double	void		The mean error per pixel computed when an image is color reduced. This parameter is only valid if verbose is set to true and the image has just been quantized.
monochrome	bool	void	bool flag_	Transform the image to black and white
montage- Geometry	Geometry	void		Tile size and offset within an image montage. Only valid for montage images.
normalized- MaxError	double	void		The normalized max error per pixel computed when an image is color reduced. This parameter is only valid if verbose is set to true and the image has just been quantized.
normalized- MeanError	double	void		The normalized mean error per pixel computed when an image is color reduced. This parameter is only valid if verbose is set to true and the image has just been quantized.
packets	unsigned int	void		The number of runlength-encoded packets in the image
packetSize	unsigned int	void		The number of bytes in each pixel packet
page	Geometry	void	const Geometry &pageSize_	Preferred size and location of an image canvas. Use this option to specify the dimensions and position of the Postscript page in dots per inch or a TEXT page in pixels. This option is typically used in concert with density. Page may also be used to position a GIF image (such as for a scene in an animation)
penColor	Color	void	const Color &penColor_	Pen color to use when annotating on or drawing on image.
penTexture	Image	void	const Image & penTexture_	Texture image to paint with (similar to penColor).
pixelColor	Color	unsigned int x_, unsigned int y_	unsigned int x_, unsigned int y_, const Color &color_	Get/set pixel color at location x & y.
quality	unsigned int (0 to 100)	void	unsigned int quality_	JPEG/MIFF/PNG compression level (default 75).
quantize- Colors	unsigned int	void	unsigned int colors_	Preferred number of colors in the image. The actual number of colors in the image may be less than your request, but never more. Images with less unique colors than specified with this option will have any duplicate or unused colors removed.
quantize- ColorSpace	ColorspaceType	void	ColorspaceType colorSpace_	Colorspace to quantize colors in (default RGB). Empirical evidence suggests that distances in color spaces such as YUV or YIQ correspond to perceptual color differences more closely than do distances in RGB space. These color spaces may give better results when color reducing an image.
quantize- Dither	bool	void	bool flag_	Apply Floyd/Steinberg error diffusion to the image. The basic strategy of dithering is to  trade  intensity resolution  for  spatial  resolution  by  averaging the intensities  of  several  neighboring  pixels. Images which  suffer  from  severe  contouring  when  reducing colors can be improved with this option. The quantizeColors or monochrome option must be set for this option to take effect.
quantize- TreeDepth	unsigned int	void	unsigned int treeDepth_	Depth of the quantization color classification tree. Values of 0 or 1 allow selection of the optimal tree depth for the color reduction algorithm. Values between 2 and 8 may be used to manually adjust the tree depth.
rendering- Intent	RenderingIntent	void	RenderingIntent render_	The type of rendering intent
resolution- Units	ResolutionType	void	ResolutionType units_	Units of image resolution
rows	unsigned int	void		The number of pixel rows in the image
scene	unsigned int	void	unsigned int scene_	Image scene number
signature	string	bool force_ = false		Image MD5 signature. Set force_ to 'true' to force re-computation of signature.
size	Geometry	void	const Geometry &geometry_	Width and height of a raw image (an image which does not support width and height information).  Size may also be used to affect the image size read from a multi-resolution format (e.g. Photo CD, JBIG, or JPEG.
strokeAntiAlias	bool	void	bool flag_	Enable or disable anti-aliasing when drawing object outlines.
strokeColor	Color	void	const Color &strokeColor_	Color to use when drawing object outlines
strokeDashOffset	unsigned int	void	unsigned int strokeDashOffset_	While drawing using a dash pattern, specify distance into the dash pattern to start the dash (default 0).
strokeDashArray	const unsigned int*	void	const unsigned int* strokeDashArray_	Specify the pattern of dashes and gaps used to stroke paths. The strokeDashArray represents a zero-terminated array of numbers that specify the lengths (in pixels) of alternating dashes and gaps in user units. If an odd number of values is provided, then the list of values is repeated to yield an even number of values.  A typical strokeDashArray_ array might contain the members 5 3 2 0, where the zero value indicates the end of the pattern array.
strokeLineCap	LineCap	void	LineCap lineCap_	Specify the shape to be used at the corners of paths (or other vector shapes) when they are stroked. Values of LineJoin are UndefinedJoin, MiterJoin, RoundJoin, and BevelJoin.
strokeLineJoin	LineJoin	void	LineJoin lineJoin_	Specify the shape to be used at the corners of paths (or other vector shapes) when they are stroked. Values of LineJoin are UndefinedJoin, MiterJoin, RoundJoin, and BevelJoin.
strokeMiterLimit	unsigned int	void	unsigned int miterLimit_	Specify miter limit. When two line segments meet at a sharp angle and miter joins have been specified for 'lineJoin', it is possible for the miter to extend far beyond the thickness of the line stroking the path. The miterLimit' imposes a limit on the ratio of the miter length to the 'lineWidth'. The default value of this parameter is 4.
strokeWidth	double	void	double strokeWidth_	Stroke width for use when drawing vector objects (default one)
subImage	unsigned int	void	unsigned int subImage_	Subimage of an image sequence
subRange	unsigned int	void	unsigned int subRange_	Number of images relative to the base image
tileName	string	void	const string &tileName_	Tile name
totalColors	unsigned long	void		Number of colors in the image
type	ImageType	void		Image type
verbose	bool	void	bool verboseFlag_	Print detailed information about the image
view	string	void	const string &view_	FlashPix viewing parameters.
x11Display	string (e.g. "hostname:0.0")	void	const string &display_	X11 display to display to, obtain fonts from, or to capture image from
xResolution	double	void		x resolution of the image
yResolution	double	void		y resolution of the image

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

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

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

Image image("cow.png"); // Obtain pixel region with size 60x40, and top origin at 20x30 int columns = 60; PixelPacket *pixel_cache = image.GetPixels(20,30,columns,40); // Set pixel at column 5, and row 10 in the pixel cache to red. int column = 5; int row = 10; PixelPacket *pixel = pixel_cache+row*columns*sizeof(PixelPacket)+column; pixel = Color("red"); // Save updated pixel cache back to underlying image image.syncPixels(); image.write("horse.png");

The image cache supports the following methods:
 

Image Cache Methods

Method	Returns	Signature	Description
getPixels	PixelPacket*	int x_, int y_, unsigned int columns_, unsigned int rows_	Transfers pixels from the image to the pixel cache as defined by the specified rectangular region. Modified pixels may be subsequently transferred back to the image via syncPixels.
setPixels	PixelPacket*	int x_, int y_, unsigned int columns_, unsigned int rows_	Allocates a pixel cache region to store image pixels as defined by the region rectangle.  This area is subsequently transferred from the pixel cache to the image via syncPixels.
syncPixels	void	void	Transfers the image cache pixels to the image.
readPixels	void	QuantumTypes quantum_, unsigned char *source_,	Transfers one or more pixel components from a buffer or file into the image pixel cache of an image. ReadPixels is typically used to support image decoders.
writePixels	void	QuantumTypes quantum_, unsigned char *destination_	Transfers one or more pixel components from the image pixel cache to a buffer or file. WritePixels is typically used to support image encoders.