graphics

I recently made what I thought was a transparent PNG but when I uploaded it onto the website it was transparent in Firefox but not in IE6. Apparently IE 6 doesn’t support 24-bit PNGs with alpha channel so you need to convert the image to 8-bit.

1. Open the original image.
2. Set a proper background colour as oposed to it being transparent. It is best to make this colour similar to the background colour of the website to generate the antialiasing in your image borders in order for the image to blend nicely.
3. Flatten the image (Image - Flatten image).
4. Add an alpha channel (Layer - Transparency - Add alpha channel).
5. Select the background color (Selection - By color).
6. Clear the background colour (Edit - Clear).
7. Convert the image to indexed color (Image - Mode - Indexed color).
8. Save the image to the final PNG file (File - Save as) and remember to check: Save color values from transparent pixels.

Simple method:

 convert -resize 16x16 image.png favicon.ico

More advanced method: you need the ppmtowinicon tool from netpbm-progs. Now:

1. Open your image with GIMP.
2. Resize the canvas to square.
3. Scale the image to 16x16 pixel.
4. Save as favicon.pnm or favicon.ppm with raw encoding.
5. Close GIMP
6. Convert to icon:

 ppmtowinicon -output favicon.ico favicon.pnm
 ppmtowinicon -output favicon.ico favicon.ppm

Just use this plugin