[GEM-dev] Alpha channel support

[B. Bogart]

Indeed nice fish...

Comments inline

james tittle wrote:
> On Mar 16, 2005, at 5:05 PM, B. Bogart wrote:

> ...um, I think you're overlooking the obvious:  green screens == yuv
> processing!  So obviously there are no alpha channels (unless you use
> the gpu alpha blending, like [blend< )...remember, yuv is gem's "native"
> colorspace on osx, but not on the other platforms...in other words, you
> should be in alpha heaven with the above films if you send [colorspace
> RGBA< to [pix_film] or [pix_movie] before loading the film...

That indeed did the trick, both TGA and TIFF work great. :) I apologize
for asking for an existing feature for so long, but indeed things were
not working very well for alpha channels in Linux when I needed this
functionality and got fixated on it!

Is there some fusion of YUV processing with RGBA? YUV+A? Alpha channels
are really handy, but it seems that the best performance would be to use
YUV to get the performance out of the RGB part of the image and keep the
alpha channel. (maybe the alpha channel could be compressed similarly to
the Luminance channel in YUV.) Just thinking aloud.

I'm really looking forward to the fast colour-space convertions!

thanks Jamie for all your support.

It would be really great to get you guys up here to do a serious
masterclass in Gem.

Oh and I've attached my old "dynamics" pmpd patch (compatible with the
stable pmpd release) using nice drop-shadow bitmaps instead of the old
vector ones.

B>

> hth,
> james
>
> ps:  otoh, you could always add [pix_rgba] after [pix_film], but this
> will be sloooow...but not for too much longer, as I've been altivec'ing
> the color conversions :-)
>
>
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