GraphicsMagick has a number of functions that allow you to read, manipulate, write, or display an image. These functions are accessible through the various tools or the object-oriented Perl interface, PerlMagick. However, you can also access the functions directly from your program through the Magick Application Programmer Interface. To invoke the functions, write your program in your favorite language while making calls to the Magick image functions and link with libGraphicsMagick.a, libGraphicsMagick.so, or Magick.dll depending on your system.
The API is divided into a number of categories:
 GraphicsMagick
	Methods to Constitute an Image
	GraphicsMagick
	Methods to Constitute an Image
	
	 GraphicsMagick
	Methods to Composite an Image
	GraphicsMagick
	Methods to Composite an Image
	
	 GraphicsMagick
	Image Methods
	GraphicsMagick
	Image Methods 
	 Methods
	to Count the Colors in an Image
	Methods
	to Count the Colors in an Image
	
	 Methods
	to Reduce the Number of Unique Colors in an Image
	Methods
	to Reduce the Number of Unique Colors in an Image
	
	 Methods
	to Segment an Image with Thresholding Fuzzy c-Means
	Methods
	to Segment an Image with Thresholding Fuzzy c-Means
	
	 Methods
	to Resize an Image
	Methods
	to Resize an Image
	
	 Methods
	to Transform an Image
	Methods
	to Transform an Image
	
	 Methods
	to Shear or Rotate an Image by an Arbitrary Angle
	Methods
	to Shear or Rotate an Image by an Arbitrary Angle
	
	 Methods
	to Enhance an Image
	Methods
	to Enhance an Image
	
	 GraphicsMagick
	Image Effects Methods
	GraphicsMagick
	Image Effects Methods
	
	 GraphicsMagick
	Special Effects Methods
	GraphicsMagick
	Special Effects Methods
	
	 GraphicsMagick
	Image Decoration Methods
	GraphicsMagick
	Image Decoration Methods
	
	 Image
	Text Attributes Methods
	Image
	Text Attributes Methods
	
	 Methods
	to Annotate an Image
	Methods
	to Annotate an Image
	
	 Methods
	to Paint on an Image
	Methods
	to Paint on an Image
	
	 Methods
	to Draw on an Image
	Methods
	to Draw on an Image
	
	 Image
	Vector Drawing Methods
	Image
	Vector Drawing Methods 
	 GraphicsMagick
	Methods to Create Image Thumbnails
	GraphicsMagick
	Methods to Create Image Thumbnails
	
	 Methods
	to Interactively Display and Edit an Image
	Methods
	to Interactively Display and Edit an Image
	
	 Methods
	to Interactively Animate an Image Sequence
	Methods
	to Interactively Animate an Image Sequence
	
	 Methods
	to Get or Set Image Pixels
	Methods
	to Get or Set Image Pixels
	
	 Working
	with Image Lists
	Working
	with Image Lists 
	 GraphicsMagick
	Cache Views Methods
	GraphicsMagick
	Cache Views Methods
	
	 Image
	Pixel FIFO
	Image
	Pixel FIFO 
	 Methods
	to Read or Write Binary Large OBjects
	Methods
	to Read or Write Binary Large OBjects
	
	 Methods
	to Read or List GraphicsMagick Image formats
	Methods
	to Read or List GraphicsMagick Image formats
	
	 Methods
	to Compute a Message Digest for an Image
	Methods
	to Compute a Message Digest for an Image
	
	 GraphicsMagick
	Registry Methods
	GraphicsMagick
	Registry Methods 
	 GraphicsMagick
	Error Methods
	GraphicsMagick
	Error Methods 
	 GraphicsMagick
	Memory Allocation Methods
	GraphicsMagick
	Memory Allocation Methods
	
	 GraphicsMagick
	Resource Consumption Methods
	GraphicsMagick
	Resource Consumption Methods
	
	 GraphicsMagick
	Progress Monitor Methods
	GraphicsMagick
	Progress Monitor Methods
	
	Here is a sample program to get you started. To find out about all the functions that are available, read the source code. Each function is delineated with a full rows of percent signs with comments describing the parameters required for the function and what it does. For ease in finding a function, they are sorted in alphabetical order.
Here is a full example of a program, demo.c, which reads multiple input files (possibly animation files) specified on the command line, resizes the image frames to 106x80, and writes the resulting animation to disk.
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <magick/api.h>
int main(int argc,char **argv)
{
  ExceptionInfo
    exception;
  Image
    *image,
    *images,
    *resize_image,
    *thumbnails;
  ImageInfo
    *image_info;
  int
    i;
  /*
    Initialize the image info structure and read the list of files
    provided by the user as a image sequence
  */
  InitializeMagick(*argv);
  GetExceptionInfo(&exception);
  image_info=CloneImageInfo((ImageInfo *) NULL);
  images=NewImageList();
  for (i=1; i< argc-1; i++)
    {
      (void) strcpy(image_info->filename,argv[i]);
      printf("Reading %s ...", image_info->filename);
      image=ReadImage(image_info,&exception);
      printf(" %lu frames\n", GetImageListLength(image));
      if (exception.severity != UndefinedException)
        CatchException(&exception);
      if (image)
        (void) AppendImageToList(&images,image);
    }
  if (!images)
    {
      printf("Failed to read any images!\n");
      exit(1);
    }
  /*
    Create a thumbnail image sequence
  */
  thumbnails=NewImageList();
  while ((image=RemoveFirstImageFromList(&images)) != (Image *) NULL)
    {
      resize_image=ResizeImage(image,106,80,LanczosFilter,1.0,&exception);
      DestroyImage(image);
      if (resize_image == (Image *) NULL)
        {
          CatchException(&exception);
          continue;
        }
      (void) AppendImageToList(&thumbnails,resize_image);
    }
  /*
    Write the thumbnail image sequence to file
  */
  if (thumbnails)
    {
      (void) strcpy(thumbnails->filename,argv[argc-1]);
      printf("Writing %s ... %lu frames\n", thumbnails->filename,
             GetImageListLength(thumbnails));
      WriteImage(image_info,thumbnails);
    }
  /*
    Release resources
  */
  DestroyImageList(thumbnails);
  DestroyImageInfo(image_info);
  DestroyExceptionInfo(&exception);
  DestroyMagick();
  return(0);
}
Now we need to compile. On Unix, the command would look something like this:
gcc -o demo demo.c -O `GraphicsMagick-config --cppflags --ldflags --libs`
As a usage example, with the input files in1.gif, in2.png, and in3.jpg, create the animation file out.miff:
demo in1.gif in2.png in3.jpg out.miff
The resulting animation may be played on an X11 display using 'gm animate out.miff'.
The GraphicsMagick-config script reproduces the options which were used to compile the GraphicsMagick utilities. Using compatible options ensures that your program will compile and run.
Another example is smile.c. Compile and execute it to display a smiley face on your X server.