Black, Alpha, Video Post
4 messages in this thread
I've run across a little problem while combining several 'layers' of
alpha-rendered TGA frames. It seems that the black background gets dithered
with quite a few dark grey pixels – a fact which decreased the compression
efficiency of my animation program by a considerable amount. Is this an effect
of 'Dither true color' and can therefore be disabled by switching this option
to off, or is it an effect which is described in the manuals and somehow could
manage to escape my ever so watchful eyes? (I haven't fiished reading the
manuals, I confess) How can I avoid black areas turn into greyblack pixel
storms? Any hint is appreciated.
Volker
Two things:
1) A true RGB 0,0,0 value will never get altered, no matter what the gamma
setting. If you're seeing dithering in the background, something in the alpha
channel somewhere is shifting a value somewhere.
2) Dither-true-color would surpress this. Additionally, if you've got any
very low-level RGB values, like 1,1,1 or 0,1,0, having gamma on will increase
them.
– G
Gary, meanwhile I've tracked down that little s*cker. It's _not_
alpha's fault, and it's _not_ Dither true color's fault, it's … strange, to
say the least. It seems that there's sneaked a R0,G0,B1 (judging by the look of
the TGA) into the background setup which is activated (admittedly by mistake).
So far, so good. Now for the strange part of the story. If I click into the
color definition area beside the 'Background' button and summon up the color
definiton requester, it tells me the setting is 0,0,0. And – if I render the
scene after pressing OK, it's absolutely black.
Summary:
A) You load the project, then render the scene – blueish background
B) You load the project, look at the color definition, then render the scene –
black background
As you use to ask for reproducible settings: I could mail you the
project file (177K, zipped), if you're interested, that is…
Thanks for your assistance,
Volker
If you want someone to look at it for you, contact Jonas or Brian via email and
I'm sure they'll try to find the time to go over it with you.
– G