Saving a bitmap with alpha channel

2158 views2 repliesLast post: 8/11/2005
I'm a programmer experimenting with bitmap manipulation. I'd like to implement bitmap tranparency. It's not too difficult to render, but it is difficult (for me) to save a bitmap with alpha data. I've been saving my images in .RAW format and manually adding the bitmap headers myself. There's got to be an easier way.

I'd like to be able to save the bitmap using the ARGB format, and preserve the anti-aliased edges (and other tranparent stuff) that photoshop provides, but I can't seem to get it to work properly. Please help. TIA.
#1
Wouldn't ya know it. After spending hours with this problem, I discover the solution minutes after I post:
http://groups-beta.google.com/group/comp.graphics.apps.photo shop/msg/[email protected] o.nz

In case the link doesn't work, here's the text:

Some programs will treat a 32-bit bitmap as having an alpha channel, is this what you mean? Right click on your layer's thumbnail, click "Select layer transparency". Click the "Select" menu, click "Save selection...". Save it as a new channel in your picture (Call it whatever you like, I prefer "Alpha"). Save as bitmap, make sure "Alpha channels" is ticked.
This may be version dependant, I use PhotoShop CS.

Works like a charm!
#2
It's fine to answer your own posts - just don't complain about the answer being off topic. :-)
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Mike Russell
www.curvemeister.com
#3