ImageMagick 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 libMagick.a, libMagick.so, or Magick.dll depending on your system.

The Magick Wand API is a new high level interface to the ImageMagick. The Wand API is recommended over the core API below.

Magick Wand

Pixel Iterator

Pixel Wand

Drawing Wand

The low level core ImageMagick API, follows.

Constitute an Image

Composite an Image

Image Methods

Count the Colors in an Image

Dealing with Image Colorspaces

Dealing with Image Profiles

Reduce the Number of Unique Colors in an Image

Segment an Image with Thresholding Fuzzy c-Means

Resize an Image

Transform an Image

Shear or Rotate an Image by an Arbitrary Angle

Enhance an Image

Add an Effect

Add a Special Effect

Decorate an Image

Set Text Attributes

Annotate an Image

Paint on an Image

Draw on an Image

Create an Image Thumbnail

Interactively Display and Edit an Image

Interactively Animate an Image Sequence

Get or Set Image Pixels

Working with Image Lists

Working with Cache Views

The Pixel FIFO

Read or Write Binary Large OBjects

Read or List ImageMagick Image formats

Compute a Message Digest for an Image

The Registry

Dealing with Errors

Memory Allocation

Monitor or Limit Resource Consumption

Monitor the Progress of an Image Operation

Deprecated 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. Most of the image functions are found in image.c and effects.c.

Here is a full example of a program, demo.c, that reads a GIF image, creates a thumbnail, and writes it to disk in the MIFF image format.

    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <magick/api.h>

    int main(int argc,char **argv)
    {
      ExceptionInfo
        exception;

      Image
        *image,
        *images,
        *resize_image,
        *thumbnails;

      ImageInfo
        *image_info;

      /*
        Initialize the image info structure and read an image.
      */
      InitializeMagick(*argv);
      GetExceptionInfo(&exception);
      image_info=CloneImageInfo((ImageInfo *) NULL);
      (void) strcpy(image_info->filename,"image.gif");
      images=ReadImage(image_info,&exception);
      if (exception.severity != UndefinedException)
        CatchException(&exception);
      if (images == (Image *) NULL)
        exit(1);
      /*
        Turn the images into a thumbnail sequence.
      */
      thumbnails=NewImageList();
      while ((image=RemoveFirstImageFromList(&images)) != (Image *) NULL)
      {
        resize_image=ResizeImage(image,106,80,LanczosFilter,1.0,&exception);
        if (resize_image == (Image *) NULL)
          MagickError(exception.severity,exception.reason,exception.description);
        (void) AppendImageToList(&thumbnails,resize_image);
        DestroyImage(image);
      }
      /*
        Write the image as MIFF and destroy it.
      */
      (void) strcpy(thumbnails->filename,"image.miff");
      WriteImage(image_info,thumbnails);
      DestroyImageList(thumbnails);
      DestroyImageInfo(image_info);
      DestroyExceptionInfo(&exception);
      DestroyMagick();
      return(0);
    }

Now we need to compile. On Unix, the command would look something like this:

    setenv LD_LIBRARY_PATH /usr/local/lib
    gcc `Magick-config --cflags --cppflags` demo.c `Magick-config --ldflags --libs`

Now lets port the above program to use the Magick Wand API:

    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <wand/magick_wand.h>
    
    int main(int argc,char **argv)
    {
    #define ThrowWandException(wand) \
    { \
      char \
        *description; \
     \
      ExceptionType \
        severity; \
     \
      description=MagickGetException(wand,&severity); \
      (void) fprintf(stderr,"%s %s %ld %s\n",GetMagickModule(),description); \
      MagickRelinquishMemory(description); \
      exit(-1); \
    }
    
      MagickBooleanType
        status;
    
      MagickWand
        *magick_wand;
    
      /*
        Read an image.
      */
      magick_wand=NewMagickWand();  
      status=MagickReadImage(magick_wand,"image.gif");
      if (status == MagickFalse)
        ThrowWandException(magick_wand);
      /*
        Turn the images into a thumbnail sequence.
      */
      MagickResetIterator(magick_wand);
      while (MagickNextImage(magick_wand) != MagickFalse)
        MagickResizeImage(magick_wand,106,80,LanczosFilter,1.0);
      /*
        Write the image as MIFF and destroy it.
      */
      status=MagickWriteImages(magick_wand,"image.miff",True);
      if (status == MagickFalse)
        ThrowWandException(magick_wand);
      return(0);
    }

To compile, type:

    cc `Wand-config --cflags --cppflags` demo.c `Wand-config --ldflags --libs`

For C++, use:

    c++ `Magick++-config --cxxflags --cppflags` demo.cpp `Magick++-config --ldflags --libs`