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#1 Jamie Metzger

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Posted 18 June 2009 - 06:55 AM

First off, Red ALERT
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I've tried playing with all of these settings, and exporting 2K tiffs and 1K tiffs. I've hardly ever noticed any differences with DRX (wtf is that?), De bayer and De noise.

I understand that the last two have something to do with sharpness and possibly cleaning up noise, but what's DRX? I've searched the labyrinth of the Reduser forum to no avail.

Next; I've had issues in the past with exporting footage using the REDCODE codec in final cut. Here is a link to the thread I started; still don't have a definite answer to why this occurred

What I'm asking, why do we have so many choices for LUT and Colorspace? I might be wrong, but isn't REDCODE not a "supported" color space, hence my issues? Am I wrong?


What's the deal with PD Log, and Linear? Why/when would you use these? Also, when you grade your images, do you have a colors pace in mind? Or do you change the options till you find something you like?

thanks, I have more questions related to Redcine, but I'll wait.

Jamie
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#2 David Mullen ASC

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Posted 18 June 2009 - 09:59 AM

REDCODE is a compression scheme for RAW footage, not a color space. Basically a RAW Bayer image doesn't really have a color space until it is converted to color, and then you have to pick one.

As for linear, I think some people like to color-correct digital cinematography in 12-bit linear as opposed to converting it to 10-bit Log.

As far as PD log, not sure what that is.
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#3 Robert Niessner

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Posted 18 June 2009 - 10:25 AM

I've tried playing with all of these settings, and exporting 2K tiffs and 1K tiffs. I've hardly ever noticed any differences with DRX (wtf is that?), De bayer and De noise.


DRX = Dynamic Range Extension
If you got a clip with very bright highlights you can dial the highlights back - without getting a color cast like on video. But be aware that this setting does not work well in every situation - fire for example should be treated with care (set DRX to a low value).

DeBayer means how precise the debayering algorithm used is. The better the more CPU power it takes.
Debayering converts the Bayer grey pattern of the CMOS to the RGB image.

De Noise means that the image gets put through a denoising algorithm - it's not very effective against true noise but can help with some chroma noise and color moiree.

OLPF compensation will dial in some sharpening, better leave it to LOW or OFF and sharpen your image later, it can produce some nasty dark lines in the highlight contrast border.
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#4 John Sprung

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Posted 18 June 2009 - 02:48 PM

What I'm asking, why do we have so many choices for LUT and Colorspace?


There are two questions here.

LUT's are basically a good thing. They can be used to implement your creative decisions and make dailies that look the way you want. They can also be used to convert between colorspaces.

As for colorspaces, well, there's the old joke: "We love standards, we have lots of them." To display colors consistently, you have to have a standard colorspace. Could we make one colorspace work for everything? It depends what we need it to do.

How about a colorspace that covers everything we can see with normal trichromatic human vision? Not only possible, it was done back in 1931, it's called CIE 1931 big (X,Y,Z) space. By taking brightness out of it, they also did a convenient two dimensional representation that just covers color, CIE 1931 little (x,y) space. It's that sort of shark-fin shaped diagram you see all over the place with colors on it:

http://www.efg2.com/...hromaticity.htm

So, why not use CIE 1931 for everything? We do, except when we need to not waste code values on colors that the actual equipment we're working on can't handle. Unfortunately, that's most of the time. Each set of display primaries can reproduce any color that falls inside a triangle in (x,y) space that has the primaries as its corners. Likewise, a camera can only distinguish between colors that land inside the triangle defined by its primaries.

So, there's the temptation -- not sufficiently resisted temptation -- to standardize a colorspace for every new thing that comes down the pike. It's always a cost/benefit analysis. We can get a bigger triangle in (x,y) space and handle more colors, but we have yet another standard to keep track of and convert to and from -- thus expanding the glut of LUT's.




-- J.S.
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#5 Jamie Metzger

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Posted 18 June 2009 - 05:18 PM

DRX = Dynamic Range Extension
If you got a clip with very bright highlights you can dial the highlights back - without getting a color cast like on video. But be aware that this setting does not work well in every situation - fire for example should be treated with care (set DRX to a low value).

DeBayer means how precise the debayering algorithm used is. The better the more CPU power it takes.
Debayering converts the Bayer grey pattern of the CMOS to the RGB image.

De Noise means that the image gets put through a denoising algorithm - it's not very effective against true noise but can help with some chroma noise and color moiree.

OLPF compensation will dial in some sharpening, better leave it to LOW or OFF and sharpen your image later, it can produce some nasty dark lines in the highlight contrast border.


the OLPF feature sounds familiar; If you don't sharpen here, where/when do you sharpen?

Also, David Mullen: Regarding the LUT's and Colorspace; I've seen people changed the settings until they achieved something pleasing...I can't imagine this is a good practice? I usually switch the Color space to Camera RGB and the output LUT to REC 709, since this is how I view on set.
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