Re: How do I edit the alpha channel?

[catfish <catfish@xxxxxxxxxxxx>]

> I am trying to use GIMP as a sprite creation/editing tool. I'm working on recreating an old Macintosh game that my dad was developing in the early 90's. The sprites he used were 8-bit color and had separate 1-bit masks (black and white). I've converted the images from the Macintosh PICT format to PNG and opened them with GIMP, but once I add the alpha channel to the sprite image, I have no way of adding the black and white mask image to the channel. I've tried everything and what documentation I could find on GIMP's site doesn't actually mention how to add pixels to the alpha channel.
Sounds like your best bet is to work with Layer Masks. This page has a 
tutorial that covers layer masks (and more): 
http://www.gimp.org/tutorials/The_Basics/ . Basically keep your sprite 
image on a standard layer then add a Mask to that layer and place your 
mask image into it. Then using the Alt and Ctrl keys you can easily 
view/edit the mask as you need. It also allows you to separate the 
image/mask easily to put back into your app.