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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

rgb curves

M

mtseng

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i really like using rgb curves all together
is look like
davinci resolve just have luminance curve and separate rgb curves
anyone knows if i can pull the 3 curves red blue and green channel all together?
it will facilitates my life a lot
 
Luminance is made up of RGB, so adjusting the luminance IS adjusting all 3 colours at the same time!
 
ericyoung said:
Luminance is made up of RGB, so adjusting the luminance IS adjusting all 3 colours at the same time!
Click to expand...

Not necessarily. I don't have access to a DaVinci right now so I can't say how their implementation works. People are often lax in how they use terminology. Luminance curves may mean what others call "master" ie RGB ganged together. A luminance curve independent of chrominance is not the same thing – look at a Y'CbCr colour corrector like the 3-way colour corrector in FCP to see the difference.
 
The Curves in REDCine-X are all RGB curves. They either adjust the individual curve for that channel, or all three at once.

Davinci does indeed have a Y curve where you can adjust luma independent of chroma. REDCine-X does not have this particular type of curve.

Graeme
 
Graeme Nattress said:
The Curves in REDCine-X are all RGB curves. They either adjust the individual curve for that channel, or all three at once.

Davinci does indeed have a Y curve where you can adjust luma independent of chroma. REDCine-X does not have this particular type of curve.

Graeme
Click to expand...

But does it have separate RGB curves. AFAIK DaVinci doesn't have curves in its metadata-controll...
 
You're right. As far as I can see they don't expose the curves or their metadata to the user.

Graeme
 
Gunleik Groven said:
But does it have separate RGB curves.
Click to expand...

Yes, looking at the manual Resolve does have separate RGB curves. You can also copy a curve from one to the other, but that's not the same as ganging all three together and seeing the result dynamically as you adjust the curve.
 
Storm, Scratch and at least one more I know (un-public beta) fortunately does...

I have a hard time seeing good raw online without full curve controll in the meta-stage...

(Not suggesting that any of the apps I mention, but Scratch - are grading tools...)
 
DaVinci allows you to adjust R, G and B curves individually. Also, an overall luminance curve.

When I started using it, I also was looking for the old "RGB all at once" curve. Eg you adjust not just brightness but saturation at once...

Now I miss it less - because I found I could get a similar result by just dialing up saturation at the same time as I put in an S-curve.

To be honest, I'd love to have all of them, eg: R, G, B, Luma and RGB.

But:
- DaVinci way (R, G, B and Luma, plus Saturation control)
- beats the non DaVinci way (R, G, B and RGB plus Saturation control)

In general for me now.

Bruce Allen
www.boacinema.com
 
Can copy the curves

Can copy the curves

I discover that if i hold option key and copy paste the curves in luminance red blue and green channel i get a same result of a normal curve

is just the smothness in the transitions poits now in the curves that i miss off now.
And a way that pull all the curves toguether in the same time to me see the things more properly.

And what i miss too is the ability to use the keyboard arrows to control the curves more precisely like in photoshop.

not that davinci is bad is just tools that i used to that i miss.
 
I have been asked about the RED curves controls but we have for now decided not to spend engineering time on them as the Resolve Custom Curves process the image at 32 bit floating point, higher than 12 bit integer, and only DaVinci processes YRGB giving greater range and control, technically. What it seems many colorist are looking for is greater usability of the existing curve control. Thanks for the feedback guys.
Peter
 
Peter, the curves in the SDK (and the image processing in general) are not processed in 12bit integer! The purpose of the curve control in the RAW development is to work directly on the RAW data. The curve control is also in camera, so if you adjust the curve in camera, as some users do, you've got to see that when you open the RAW file. Just the other day I was examining some shots that looked really really funky on Davinci until the metadata was all reset. We found the user had used a custom curve that was not displayed and nobody knew it was there until we opened the R3D in REDCine-X and saw that the curve metadata was in use.

Graeme
 
Graeme Nattress said:
Peter, the curves in the SDK (and the image processing in general) are not processed in 12bit integer!
Graeme
Click to expand...

So ... what exactly is the RED SDK processing precision? As far as I understand it delivers fixed point (integer) values ... in 8, 10, 12 or 16 bits

Same question for Red Rocket processing ...
 
It delivers 16bit integer or half-float outputs. Internal processing is done in a mix of 16bit integer and floating point where appropriate in the chain. RED One R3D files are 12bit, so we take care to more than preserve that precision throughout the image processing chain.

Graeme
 
Graeme Nattress said:
The curve control is also in camera, so if you adjust the curve in camera, as some users do, you've got to see that when you open the RAW file. Just the other day I was examining some shots that looked really really funky on Davinci until the metadata was all reset. We found the user had used a custom curve that was not displayed and nobody knew it was there until we opened the R3D in REDCine-X and saw that the curve metadata was in use.
Click to expand...

Ooh, that's a bit of a doozy. Haven't run across that one yet (And, to be honest, probably won't, since for the most part I treat camera settings as reference-only and do a reset pre-grade) but it's good to know about.
 
Graeme Nattress said:
Peter, the curves in the SDK (and the image processing in general) are not processed in 12bit integer! The purpose of the curve control in the RAW development is to work directly on the RAW data. The curve control is also in camera, so if you adjust the curve in camera, as some users do, you've got to see that when you open the RAW file. Just the other day I was examining some shots that looked really really funky on Davinci until the metadata was all reset. We found the user had used a custom curve that was not displayed and nobody knew it was there until we opened the R3D in REDCine-X and saw that the curve metadata was in use.

Graeme
Click to expand...

Graeme, if the curves are acting on the raw data, how do they relate to the other controls in the RedCine data path? I was doing some experimenting with channel mixing to B&W in RCX the other night, and I found an interesting phenomenon: If I reduced the saturation to zero, I could use the RGB controls like the Channel Mixer in Photoshop and get the results I expected. But when I started playing with RGB curves, the B&W image is being colored. (like a duotone, not full color) I expected this in the lift, gamma, gain module, but not in curves.

This got me thinking about the signal path in After Effects, where the raw conversion is done in the import module, and everything after that is working with the RGB result of that import step. If RCX curves are acting on the raw data, then they are not doing that, but how do they relate to the other controls? Are all of them acting on the raw data and affecting its debayering and conversion to RGB? or are some of them acting on the result of that process?
 
There an order of operations in the controls, but they all refer back to the raw data meaning at no point in the raw conversion chain to we clip the data. Say you set contrast up high and you see some clipping in the highlights in the image. The user curve comes after contrast, so you could lower the levels and un-clip that highlight.

Graeme
 
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