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View Full Version : Advice required - Color space & LUT


amjaffers
12-14-2006, 09:36 PM
Within the White Balance Tool a custom Color Space can be selected.

Q. My question, Where does one obtain the correct color space settings required?
For example, the live footage is shot on 35ml (supplied as HD files).

Q. And; is the color space refering to the film stock used or the transfered HD frames?



On the subject of color space.

Q. Are LUT's used only when working in Log space.
(Using an LUT that is a representation of the final output).

Q. Or can an LUT be used for working in 8bit images for TV broadcast -
and if so what kind of LUT would be used. ie. an LUT for TV output?

ch33rs in adv,
AJ

amjaffers
12-15-2006, 03:29 AM
Any Suggestions? Links to references, anything?

I have searched this forum without result.

Aneks
12-16-2006, 03:13 AM
On the subject of color space.

Q. Are LUT's used only when working in Log space.
(Using an LUT that is a representation of the final output).

Q. Or can an LUT be used for working in 8bit images for TV broadcast -
and if so what kind of LUT would be used. ie. an LUT for TV output?

LUT's are generally used to compensate for the gamma encoding of a scanned film image which is converted to log and delivered via a digital file. This process was developed by Kodak to compress the high-dynamic range of film negative into a smaller digital packet for visual effects work. LUT's are commonly used to delog an image thereby bringing it into a 'linear to light' colourspace which is equivalent to that used by all compositing programs (with the exception of Cineon), therefore allowing the compositor to perform liner mathematical operations on imagery. This footage is then re-logged with an inverse LUT before being sent back to film.

The process of estimating or representing the final output of film plate generally involves a viewer based lookup which will adjust the diplay gamma response of an image without actually effecting the image itself. This vLUT system is common to most film compositing packages such as Shake, Fusion, Combusiton and Nuke.

You can use a custom LUT to estimate the look of an 8bit image for final broadcast, baring in mind this a very different type of lookup than you would use to delog or relog an scanned film plate. Provided you know the gamma response of your video hardware. Using a hardware i/o card and a broadcast monitor is a much better approach as it is not emulating this task but rather actually performing it.

In terms of actual settings for you LUTs this information should be provided by your film lab or post supervisor (although the later is wishful thinking). It is not the sort of thing you can just take a stab at and hope. When you say you are working with film at HD, what format is it being dleivered at and what bit depth ? ie is 8bit video or 10bit log 16 bit lin ?

p.s.

Did you used to work at animal on C-net stuff?

amjaffers
12-18-2006, 06:16 AM
So I hear .............what format is it being dleivered at and what bit depth ? ie is 8bit video or 10bit log 16 bit lin ?
p.s.Did you used to work at animal on C-net stuff?

Thx for reply m8. So basically your saying I dont really need use it.

The film was transfered to HD 1080p 8bit. Were outputting Pal D1.

No I never worked at Animal. I worked on a C-net flash splash page back in 2000 :|

Aneks
12-18-2006, 06:42 AM
if it was taken down to 8 bit and is heading out to broadcast at PAL. then a broadcast monitor is your best bet. Invest in a deckilink or AJA card for like 1000bucks and a good sony broadcast monitor and be 100% safe.

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