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what happened to color key

Posted: Thu May 26, 2005 5:29 pm
by yeonil
Now it isn't possible to assign a custom color of bg when rendering with "Key" button.
The bg is always black, and I think it's a major downgrade, because I didn't manage to detour this problem with sequence editor or an external application
(using ex. app. involves some potentially erroneus steps, as there happen to be some black on my render that i want to keep)
(using sequence editor blurs foreground with bg, therefore making it useless, as I need the fg to be strictly cut-out from bg, not anti-aliased, despite OSA)

Is this a bug, and if not, how i can do the thing now, if ever possible, and mainly:
when will this feature be availible?

Thanks in advance


Posted: Thu May 26, 2005 7:02 pm
by ton
It is the 'key' alpha option, it is about alpha rendering.
A color assigned for zero alpha pixels was useless... whatfor did you need it?

BTW; you can still code a simple sequence effect to do that, if you need. Just color pixels with alpha = 0.

Posted: Thu May 26, 2005 11:32 pm
by yeonil
I needed it for rendering tiles with #FF00FF background with OSA, but in such manner that they are not blending with the pink bg, so i could put them into the gameflow without any sequence/or external app editing...
i checked alpha over seq, and it blended the fg with bg, so it was useless for me...
i must check the other seq. plugins then...

but still... it was useful, and easy... i will miss that feature.

Thank You for such fast reply! I am honoured!


Posted: Fri May 27, 2005 12:16 am
by yeonil
ok, i found chromakey rgb a nearly ideal solution of my problem.
However, it is not as accurate as the Key function, because during render, blender knows which pixel is black because it is background, and which is black, but it is rendered to be so.
Chromakey plugin treats every pixel equally....

but if there is no other solution, i will fix the errors in Photoshop...


Posted: Fri May 27, 2005 1:00 am
by theeth
Can't you just use the Sequencer to put a color in the background with an alphaover effect?


Posted: Fri May 27, 2005 6:13 am
by yeonil
As I said, alphaover effect makes (unless I messed up with something, but there are no preferences for that effect) a smooth transition between layers, while the key function did not.
It is crucial here, because with alphaover plugin I have trouble separating those two layers (fg & bg) because of that small transition, and to avoid pink outline, like in old cheap bluebox films
I must fix the border manually, which is 1)unwanted work 2)highly inaccurate

I hope I provided You now a reason for this feature to exist now :D
But still... I shall seek some "chromakey alpha" plugin or sth... (I'm no coder, sorry)


Posted: Fri May 27, 2005 6:47 am
by theeth
yeonil wrote:As I said, alphaover effect makes (unless I messed up with something, but there are no preferences for that effect) a smooth transition between layers, while the key function did not.
Did you disable OSA when doing your sequence rendering?


Posted: Fri May 27, 2005 7:24 am
by yeonil
Ok, now I made it, finally.
I combined chromakey rgb, zutils, scene and a pink bitmap and archieved the effect i needed.
Those plugins should be availible from the bare blender install... with a handy tut maybe :D (maybe I will write sth if there is no volounteers)

So, the render now clearly cutouts from the bg
(pasted a zoom in the middle)

My only problem now is that i cannot incorporate the glow plugin on the effect on the first pass, but that's propably a question for Elysiun :D


Posted: Sun May 29, 2005 1:39 am
by yeonil
update: this setup do not work flawlessly, mainly because of a bug in zutils:
mask eats more pixels than it is designed to (2 or 3 more) and therefore some small parts of image which are surrounded by the masked area get eaten... but it is not so annoying...
And then, if i set up this rack of plugins, i can not add glow to the effect, it's a n excluding choice situation (my setup OR glow (or do it in 2 passes))

The point is:

Assigning a color to alpha=0 pixels in "Key" mode IS a feature.
Is it hard to bring it back?