#Alpha channels (again?)
5 messages in this thread
I'm having trouble bringing a 32 bit PICT with alpha channel into ADPro.
When I bring it in, in REPLACE mode, the colors are rotated, indicating
the alpha channel is there. When I try to compose the image into another,
the "ALPHA ONLY" box is ghosted and there is no "USE INCOMING ALPHA" in
the Alpha selection. What Gives?
BTW what formats support embedded alpha channels?
-Steve
Alpha support for PICT should be working. Could you e-,ail this partticular
image so we can see if theie are any peculiar elements to it?
Chris Edgin
ERI tech.
Just for your information, my IFF Deep loader supports 32 bit RGB+Alpha images,
and works just fine with the "Use incoming Alpha" option. In fact it works fine
in every mode except for "Load as Alpha", because of an apparent BUG in ADPro!
However, despite mentioning this BUG a few times I have not had an
acknowledgement, so either:-
1) No-one has heard me.
2) They've fixed it but I don't know about it.
3) They're working on it.
4) They're ignoring it.
Either way it'd be nice to know 🙂
Martin Kay,
ZEN Computer Services
Martin,
<<IFF Deep loader>> ? I thought IFF was limited to 24 bit plane.
Besides, how do you save an alpha with an IFF image? How do other programs
deal with this?
ER wants me to send them my "offending" PICT file, which I will do next
week. The image comes from Photoshop and I've tried saving the alpha
channel, selecting it as "Use video alpha" (if you use Photoshop, you'll
know what that means). I've also tried saving it with a "plain vanilla"
alpha. Neither loads properly into ADPro.
-Steve
Steve,
The IFF ILBM format is indeed limited to 24 bit-planes. However, IFF covers
more than just bitplane images, although to many people it is synonymous with
InterLeaved BitMaps. The DEEP variant was developed by Tecsoft (for TVPaint)
and ACS (producers of the Harlequin 32 bit RGBA graphics card) as a faster way
of dealing with 24 bit images that are handled as "one byte per pixel colour",
rather than as bit-planes. IFF Deep can also handle 32 bit RGB+Alpha as easily
as 24 bit RGB. Unfortunately the only programs I know of which save 32 bit RGBA
images are TV Paint and my own ZCG32 Character Generator.
Unfortunately I don't know Photoshop (apart from by reputation), nor the PICT
file format or the options you have when saving. If the "Use incoming Alpha"
option doesn't work with a 32 bit RGBA image, then I'd try saving the Alpha as
an 8 bit greyscale, the "main" image as 24 bit RGB, and see if these will load
into ADPro. You could then save them out as 8 bit grey and 24 bit RGB IFF
files, and these WILL load back in using the 8 bit grey in "Load as Alpha"
mode, and the 24 bit RGB with "Use Alpha memory". However, it'd be better if
the PICT loader worked as expected 😎
-Martin