#video rendering
8 messages in this thread
I'm looking for suggestions to create a negative video black background
when rendering to video tape or D2 to avoid creating a mat for colors that
are dark. Any suggestions would be appreciated. Thanks
I'm not entirely sure I understand what you're trying to do, but I think
taking a look at Ron Scott's QFX product line would be a step in the right
direction. Your local Targa/Truevision dealer should be able to help you.
Sounds like you need to use ALPHA SPLIT to make files that you can then
record to tape to make an animated MATT.
I take it you want to Chroma-key you animation on top of another video
segment?
Jamie
Jamie,
I've also had clients request that we supply our animations on
"superblack". We haven't found any way to achieve this, though, so we
always supply a matte animation.
Although we have found that using a seperate matte animation gives better
quality, the TV studios would like superblack, because it reduces the
equipment requirements (extra source deck) to do the overlay.
Is this something that can be achieved from the software (i.e. 3DS), or is
it a hardware (i.e. framebuffer) feature?
If it can be achieved by software, that would be a good wishlist item for
Version 3 of 3DS.
-Jeff
I'm not sure what makes black 'SUPER'. I do recall that when we went to
convert our stuff to D1 we found RGB 0,0,0 to be TOO BLACK and we bumped
the video level. Could that be it?
Perhaps RGB 0,0,0 is super black? If not we'll need to know more about what
defines super black.
Jamie
Following up on the "superBlack" comment. most video suites always set to
zero black, however in order to get a good "Key" the background color or
"key" must be at least 7 – 10 points below the level of the colors used.
I've been experimenting with all posible combinations of Background to no
avail. A work around was to use a down stream keyer and RGB camera and
feed a dual input that effectively gave a negative black background. works
sometime not others!
Super Black, if I am not mistaken, is simply RGB 000. "Black" that is
going to be broadcast as is should be 7.5% Gray. That is the "Black" that
editors set their waveforms to. Super black is also called "key black"
because it is used when straight chrominance keying is to be attempted
(without the aid of alpha mattes). If mattes exist, of course, it doesn't
matter what the background is (except for mixing solid key backgrounds with
non-solid source backgrounds or vice-versa). As digital matting techniques
get more sophisticated, the key-black thing will become less important.
Ken Loss-Cutler
Thanks, Jamie, for the reply. I've been utilizing the Alpha Channel / Mat
process, but I was wondering if there was another way to save the dual
rendering process. I know that negative black is not a "broadcast legal"
signal however if it was used as a background only for "Keying", you should
be able to key out the darker colors. Most of the boards that I am aware
of are "clamped" to avoid an "illegal signal" but I thought ther may be
another solution…. will keep thinking…thanks!