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Old 22 April 2015, 12:43   #34
Newbie Amiga programmer

Join Date: Jun 2012
Location: Front of my A500+
Age: 32
Posts: 109
Originally Posted by pandy71 View Post
nope, can be applied - on ECS (AGA?) bitplane can be used as ZD (genlock) plane. So 1 bit alpha can be on plane not only on CLUT entries.
I started out from the description, what you showed me, but let's just say, this is true. It would be still impossible to store the alpha, because such thing like '1-bit alpha' is not exists! In this entire thread, everybody confuses transparency with translucency and the alpha layer is the latter one. On 1-bit, you can only store transparency (0 = transparent, 1 = opaque); to have a real alpha layer, you'll need at least two bits, then at least, you'll have two translucent state.
Do you have an idea how this image

would look like with an '1-bit alpha'? Like this!

(Replace the black with anything you want, but you get the idea.)
Originally Posted by Thorham View Post
It makes a lot more sense then storing the alpha channel in an IFF chunk that not a single program can (and likely never will) use. Furthermore, I suggested it as an option, so that the alpha channel can obtained as an 8bit gray scale BMP (easy file format, easy to use), and is not simply lost (and also the original 24bit color data).

BMP is of course very common in that it can be read by just about every image processing software in existence. This includes 8bit per pixel palette and gray scale images. BMP is anything but uncommon.

So, yes, it makes perfect sense. Whether or not jsr wants to implement it or not, is up to jsr.
Actually, both ideas are makes no sense. It does not matter, that i store the alpha layer in a custom - thus generally unusable - chunk, or in a separate file, in an alien format to the Amiga top on that: BMP is anything but common (and usable!) on the Amiga. I know, that some programs can import BMP files, but in general a BMP file is useless on the Amiga - even if palette based BMP-s can be shown after a C2P conversion - it makes no sense to store Amiga pictures in BMP, and absolutely makes no sense to store data uniterpretable for the Amiga - in a format which is alien to the Amiga.

Last edited by TCH; 22 April 2015 at 12:44. Reason: missing 'g'
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