Transparent GIFs with GIMP - Really love this open source project, GIMP. Great substitute for Photoshop -- and it's FREE!
Here's how to create a transparent GIF using GIMP...
- Open image in GIMP.
- Right click the image and go to LAYERS then ADD ALPHA CHANNEL. Nothing obvious happens, but this step adds a transparent layer underneath your image so that when colors are erased (more later) the image shows the transparent layer and show whatever under it on the screen.
- Right click on the image again and go to SELECT and then down to BY COLOR. A window that is all black opens up. Don't change any of the settings....just use the defaults for now.
- Click mouse cursor on the color in the image you want to be transparent. This color will now show up outlined.
- Right click on the image again and go to EDIT and then down to CLEAR. This erases the outlined color, leaving the image and the "transparent GIMP checker-box" replacing the color selected in previous step. This is the Gimp's way of indicating that the section is now transparent.
- Right click on the image and choose SAVE AS -- make sure to save as a GIF file if you want the transparency to work on the web.
Helpful Links
- GIMP - The GNU Image Manipulation Program: Homepage of the FREE image manipulation program. Nice substitute for Photoshop. Has windows installer. Excellent package...and FREE!
- GIMP Tutorial at UW
 | GIMP 2 for Photographers: Image Editing with Open Source Software by Klaus Goelker |