Resize animated GIF file without destroying animation

Question

I need to resize an animated GIF file without destroying the animation.

How can I do it using PHP?

Answer 1

if you have imagemagick access, you can do this:

system("convert big.gif -coalesce coalesce.gif");
system("convert -size 200x100 coalesce.gif -resize 200x10 small.gif");

this is most likely possible with the imagemagick plugin if you don't have system() access

NOTE: this may create a larger filesize though a smaller dimensions image due to coalescing essentially deoptimizing the image.

UPDATE: If you don't have ImageMagick access, you should be able to use a combination of the following steps to resize an animated gif (assuming you have GD access):

1. Detect if the image is an animated gif: Can I detect animated gifs using php and gd? (top answer)
2. Split the animated gif into individual frames: http://www.phpclasses.org/package/3234-PHP-Split-GIF-animations-into-multiple-images.html
3. Resize the individual frames: http://www.akemapa.com/2008/07/10/php-gd-resize-transparent-image-png-gif/
4. Recomposite the frames into an animated gif again: http://www.phpclasses.org/package/3163-PHP-Generate-GIF-animations-from-a-set-of-GIF-images.html

This is definitely much more intensive than the ImageMagick route, but it should be technically possible.

If you get it working, please share with the world!