rainbowify

Creates frames for a looping, colorful gif

Inspired by Bob Dylan's trippy gif (seriously, just search for those words and you'll find it). Stuff like this: http://i.imgur.com/WosTYir.gif (beware, might be too flashy).

Warning: If you're sensitive to flashing lights, some of the faster animations might not be suited for you.

You'll need:

• Octave
• The octave-image package
• ImageMagick

You can use MATLAB instead of Octave, I guess, but I don't know if something breaks when doing this.

Usage - for dummies (like me)!

1. Generate .png files by running

   octave --silent --eval "rainbowify(\"base_image, out_folder, base_name, step\")"

   • base_image: the image to rainbowify. The script has been tested with a color JPG file but shouldn't encounter problems with other color formats. Grayscale images might produce errors, though.
   • out_folder: where you want the animation frames to be output. Keep in mind that up to 64 frames will be output. Therefore, an empty folder is recommended. If omitted, frames will be output to the current folder.
   • base_name: the prefix to give each frame image. If omitted, it defaults to "out". If you use a non-empty folder (not really recommended) try to use a base name that makes the frame images easily distinguishable from other files.
   • step: this determines how many frames will be output. A higher number results in fewer frames. Valid values are integers between 1 and 64. Recommended values are 1 for slow animations, 4 for normal-speed animations and 8 for fast ones. Defaults to 4 if omitted.

2. Compile your frames into a gif!

   cdto the folder where you have the frames obtained from the previous step.

   convert -delay D ./base_name*.png -coalesce out_file.gif

   The D parameter determines gif speed (in particular, how many millisecond each frame gets), and can be combined with the previous step parameter to maintain a fluid animation that plays at the desired speed. A slow animation needs more frames; conversely, having too many frames imposes a limit on the animation's speed. I've used 1x40 (no quotes) for normal-speed animations and 1x20 for fast ones. For more information on this parameter, check the ImageMagick/convert documentation.

   Replace base_name with the base name you used in the previous step (or out if you omitted it). If you used an empty folder, as recommended, using ./*.png works too. Really, just bash stuff.

   You can use another name for the output file, obviously.

   Try playing around with ImageMagick's many options. Really, I just messed around until I got something I liked.

   Enjoy!