LinuxQuestions.org - Using ImageMagick Convert RGB -> indexed colors

Hi -

I'm trying to create animations in an old, proprietary DOS file format. I need to be able to read a set of RGBA .png images (each .png file corresponding to a frame in the animation) and convert them all to indexed color (*all* images have to share the *same* color palette).

It sounds like ImageMagick's QuantizeImages() API might be the ideal way to do this. Does this approach sound reasonable:

Code:

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <magick/api.h>

...

main ()

  ...

    // Initialize ImageMagick

  ExceptionInfo exception;

  InitializeMagick(*argv);

  GetExceptionInfo (&exception);

  ImageInfo *image_info = CloneImageInfo ((ImageInfo *)NULL);

  

  // Read all specified .png/RGBA TrueColor images into memory

  Image *images = NewImageList ();

  for (int i = 1; i < argc; i++)

  {

    strncpy (image_info->filename, argv[i], MaxTextExtent);

    Image *tmp_image = ReadImage (image_info, &exception);

    if (tmp_image == NULL)

    {

      printf ("ERROR: Can't read (%s), err= %d:%s!\n",

        image_info->filename, exception.error_number, exception.description);

      ...

    }

    AppendImageToList (&images, tmp_image);

  }

  

  // Generate color table (based on all RGBA images in list)

  QuantizeInfo quantize_info;

  GetQuantizeInfo(&quantize_info);

  QuantizeImages (&quantize_info, images);



  // Read color palette from first (now-indexed color) image

  Image *nextImage = GetFirstImageInList (images);

  ViewInfo *view_info = OpenCacheView (nextImage);

  IndexPacket *index_packet = GetCacheViewIndexes ( view_info);

  

  // Write color table to DOS animation file

  /* ... TBD ... */

  CloseCacheView (view_info);



  // Read (now-indexed color) images one at a time

  for (int i = 1; i < argc; i++)

  {

    // Read (now indexed) pixels from current image

    view_info = OpenCacheView (nextImage);

    PixelPacket *pixel_packet = GetCacheView (view_info, 0, 0, width, height);

    

    // Write pixel data to DOS file

    /* ... TBD ... */

    CloseCacheView (view_info);

    theImage = GetNextImageInList (images);

  }



  // Done

  DestroyImages (images);

  if (image_info)  

    DestroyImageInfo(image_info);

  DestroyMagick();