Transparent grave backgrounds.

[chronoswin]

I'm pulling my hair out trying to get transparent backgrounds, I've made the background RGB 0-0-0 and still it shows up in game with a big black background. I don't have photoshop, using gimp.

[CyberShadow]

Gimp's downsampling code has issues. See http://worms2d.info/Colour_map#The_GIMP for instructions on how to get a "pure black" in the downsampled image.

[chronoswin]

No luck, was already set to 0-0-0 still doesn't work. Also tried ms paint same problem. Any other suggestions?

[Nando]

I suppose you mean a "big black background" as in solid black terrain?
If that's the case the colour used can't be #000000.

When reducing the number of colours, GIMP will usually change the black background colour to a similar colour like, for instance, #000100, in the process of creating an optimised palette.

If the instructions on WKB don't work for you (although I don't really see why they shouldn't), you can still avoid the problem by doing the following:

1: Select all black (#000000) parts of your map and delete them (thus making them transparent)
2: Reduce colours to 112 (or less)
3: Change colour mode to RGB again
4: Fill the transparent parts with pure black
5: Reduce colours to 113 (or 1 more than you used before)
6: Save as .png

This method should be fool-proof :p