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 API is divided into a number of categories: Constitute an Image Composite an Image Image Methods Count the Colors in an Image 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 Draw with Vectors 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 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 JPEG image, creates a thumbnail, and writes it to disk in the PNG image format.
        #include <stdio.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`
Another example is smile.c. Compile and excute it to display a smiley face on your X server. For C++, use:
        g++ `Magick++-config --cxxflags --cppflags` demo.cpp `Magick++-config --ldflags --libs`
"Image manipulation software that works like magick"