Image Magick

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:

* Utility Routines to Read Image Formats
* Interactively Display an Image
* Interactively Animate an Image Sequence
* Utility Routines to Write Image Formats
* ImageMagick Image Manipulation Routines
* ImageMagick Image Effects Routines
* Graphic Gems - Graphic Support Routines
* Reduce the Number of Unique Colors in an Image
* Count the Colors in an Image
* Shear or rotate a raster image by an arbitrary angle
* Segment an Image with Thresholding and the Fuzzy c-Means Technique
* ImageMagick Error Routines
* ImageMagick Progress Monitor Routines
* Compute a Digital Signature for an Image
* Image Compression/Decompression Coders
* ImageMagick Utility Routines
* X11 Utility Routines for ImageMagick
* X11 User Interface Routines for ImageMagick
* Windows NT Utility Routines for ImageMagick
* Macintosh Utility Routines for ImageMagick
* VMS Utility Routines for ImageMagick

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 delinated 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, example.c, that reads a JPEG image, creates a thumbnail, and writes it to disk in the GIF image format.

    #include <magick.h>

    int main(int argc,char **argv)
    {
      Image
        *image,
        *scaled_image;

      ImageInfo
        image_info;

      /*
        Initialize the image info structure and read an image.
      */
      GetImageInfo(&image_info);
      (void) strcpy(image_info.filename,"image.jpg");
      image=ReadImage(&image_info);
      if (image == (Image *) NULL)
        exit(1);
      /*
        Turn the image into a thumbnail.
      */
      scaled_image=ZoomImage(image,106,80,MitchellFilter);
      if (scaled_image != (Image *) NULL)
        {
          DestroyImage(image);
          image=scaled_image;
        }
      /*
        Write the image as GIF and destroy it.
      */
      (void) strcpy(image_info.filename,"image.gif");
      WriteImage(&image_info,image);
      DestroyImage(image);
    }

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

    cc -o example -O -I/usr/local/include/magick example.c \
      -L/usr/local/lib -lMagick -lX11 -lm

If you compile with C++ you must undefine class (since it is a C++ reserved word). The class element of the Image structure in C++ is defined as c_class. Both of these requirements are illustrated here:

    #include <magick.h>
    #if defined(__cplusplus) || defined(c_plusplus)
    #undef class
    #endif

    ...

    if (image->c_class == DirectClass)


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