Maptools/Gimp Help

[RobA]

A little more streamlined is to just load the image, the right click on the "blackground layer" and use "Add Alpha Channel" then continue with the fuzzy select tool steps.

A small tip (which I didn't realize for years) is that any layer name in bold has NO alpha channel (no transparency) and non-bold layers have an alpha channel (potentially has transparency)!

If you select and delete a layer without transparency it is filled with the current BG colour, if it has transparency it is set transparent. The interesting side effect of this is you can use the eraser tool with the Alt key held down (or shift alt on some systems) and "anti-erase" or change the alpha (transparency) so that the erased stuff reappears!

-Rob A>

[torstan]

You can also use Layer-Transparency->Set Colour to Transparency with the colour select set to either white or black to get the backgrounds to be properly transparent. This works particularly well after using fuzzy select with feathered edges.

[RobA]

You can also use Layer-Transparency->Set Colour to Transparency with the colour select set to either white or black to get the backgrounds to be properly transparent. This works particularly well after using fuzzy select with feathered edges.

Be careful with that, however, as will take ALL the white out of the image and turn it transparent, so anything white will be transparent, and anything partially white (i.e. grey) will end up black and partially transparent!

-Rob A>

[torstan]

Ah, I think you've misunderstood what I meant there. The steps I'd recommend are:

1. Use fuzzy select with feathered edges to get a pretty good selection of your background.
2. Use colour to alpha from the Layer->Transparency->Colour to Alpha menu option.

The advantage of using colour to alpha is that you can vary the threshold on your fuzzy select, but you'll never completely get rid of any colours you accidentally select. I find it gives me the smoothest edges when cropping images out to use as tokens.

I entirely agree that using colour to alpha on the whole layer is a bad idea and definitely to be avoided.