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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 :)

How I would have colour graded the footage

Why do you say that about OpenGL?
 
I think Scratch powerfull color grading module is mostly based on the nvidia graphic card, not much on the cpu. Might need an update from Lucas here.
I saw a demo at NAB and it runs very nicely, playing RT while color grading even the 4k REDCDOE RAW.

Sure Color and Scratch are not in the same price range, but Color comes from Final Touch, and the 2k version was not cheap. As I have never used Final Touch, I wonder if Color is really able to play RT color corect footage, and if it is possible to use format such as dpx/tiff.
While I think Color might be a very interesting budget alternativ, I will have to see how it works and what are the limitations.
For exemple is it possible to output to broadcast monitor via HD-SDI from color or does it need to go back to FCP?

antoine.
 
Rob Lohman said:
Why do you say that about OpenGL?
Click to expand...

I've noticed problems rendering out of After Effects with OpenGL. (not that that means it is bad as a whole).

In talking to Synthetic Aperture at NAB this year they were talking about how Color and others were using OpenGL instead of the CPU and that it wasn't as high of quality.

I like the idea of having OpenGL be a part of the Red workflow as long as it doesn't reduce any of the quality. I love the speed of OpenGL, I just don't want it affecting the end quality.

Correct me if I'm wrong, I'd really like to know if my OpenGL problems have just been my own fault. :biggrin:
 
Surely it depends what you're using the GPU to do. Different GPUs may use different qualities of filtering when doing things like scaling and 3D, but when applying a customised LUT, or applying mathematical transforms to the colour channels, which is the basis of most colour correction, surely a GPU would do it at the same quality as the CPU.
 
GPUs don't implement IEEE standard floating point calculations (yet), so the results are slightly different than CPU calculations. Not sure if this is an issue with video... I don't believe it is because 32 bits should have sufficient overkill where this doesn't matter.

2- It might be that the quality differs because the algorithm is altered so it runs on a GPU well. You see this with After Effects, where the openGL render looks significantly different than the CPU render.

Though I don't think it's fair to diss GPUs because of this.

Perhaps someone who knows more about this than I do could chime in here.
 
Well two of the highend grading products that get mentioned a lot around here Scratch and Lustre both lever gpu power extensively.
 
In Lustre not all the features work on the GPU (don't know if this has changed)... so sometimes it is left off.
 
At least as far as SCRATCH is concerned...

all of our color operations are GPU-based and processed at 32-bit float. Our rendering pipeline is also GPU, so any differences or anomalies between what is seen and what is rendered are non-existent.

In general, problems arise where a GPU instruction set is being used for display, and then a CPU instruction set is being used for rendering. To be fair, if this is done properly, you will never see a difference even with the most exacting QC standards. But if it is done poorly, then there will definitely be a difference in the viewed and rendered results.

But as far as quality - it is a non-issue. A few years ago, before GPU technology really became professional quality, then sure, it was an issue. That has not been true for several years now.

Lucas
------
ASSIMILATE, Inc.
LA, CA, USA
 
So Lucas, are you saying you are talking to the gpu directly, using the manufacturers api instead of OpenGL?

Joe C.
 
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