7 replies to this topic

[coolgroupsdotcom]

Could someone tell me which image formats support alpha channels? (out of GIF, JPEG, and PNG)

Thanks.

mike
http://www.coolgroups.com/

[Reedbeta]

of those three, only PNG supports alpha channels.

[geon]

True. But GIF support simple on/off transparency, wich migt be enough in some cases.

[Kippesoep]

And, although it's not in the short list, there's also TGA. That supports alpha and is very easy to handle in code.

[geon]

BMP also handle alpha.

My favorite, though for quick tests is PSD. It is pretty bloated, so I would not use it in a final release, but it Is really convienient to just load the layer you want directly from your photoshop document.

I have some loading code here, buried in some useless alphablending stuff:
http://www.ds.hj.se/~geon/image/

[servo]

Ordinary the bitmap file cannot handle alpha blending
Maybe it is in 24 bit, but we must make the mask bitmap for blending. So just have two bitmap, one is original bitmap and other is mask bitmap...
It depends on the code in program.

[SigKILL]

When we're allready suggesting other formats, the .dss format also handles alpha channels and is probably the easiest to write an importer for as long as you include the ddraw.h or copy/paste whatever you need. The best bit is that it supports handy stuff like mipmaps, cubemaps, 3d-textures etc.etc.

-si

[isolier]

I second the .tga format. Very easy to implement...