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Computer RGB to Studio RGB – Definitive Explanation Requested…Please!
Alright, I know this question has been asked many times in this forum, but please bear with me, because I still don’t understand.
My video production involves a lot of still photos, and like many others have struggled with, when I render to the .m2T format using the YUV codec the colors do not come out the same as they were when I edited them in Photoshop. Blacks are blacker, whites are sometimes blown out, and other colors are slightly different shades – a nice blue sky will come out looking ever so slightly purple.
I’ve tried the various suggestions I’ve read in this forum. I’ve played the videos on the VLC media player but even it does not reproduce accurately. I’ve also tried using Levels with the “Computer RGB to Studio RGB” setting, and yes, it improves things and mostly solves the issue with blacks and whites. However, it doesn’t completely fix it, and it also does not solve the issue of various colors being slightly different shades than the original.
So far, the best compensation I’ve been able to come up with is to apply Contrast -0.2 and in Color Corrector apply a Gain setting of 1.05, and this actually gets the colors much closer to the originals than the Levels setting.
Incidentally, rendering to an uncompressed AVI causes none of these problems. Rendering as an .mpg or .mp4 after applying the Levels effect also seems to be pretty accurate. It’s mainly the .m2T format that has this problem.
Anyway, what I want to know is this –
1) Is it possible to render still photos to the .m2T format using the YUV codec and produce a video that EXACTLY reproduces the color of the original image?
2) If so, how?
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7 Replies
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Definitive Explanation – Ermmm?
Apologies if you know all of this below, but I’ve gotta start somewhere and I also have gaps in my knowledge. So, with those caveats in place.
Need to get the signal flow correct:
Camera detects and converts LIGHT into RGB > next the camera Converts, in-camera, to YUV > this gets ingested into Vegas as RGB, so we can see it! . . And then, after that render using YUV out on some form and then again it gets reconverted to RGB – so we can see it!
Using the computerRGB to studioRGB is a way to correct Levels.
Grazie
Video Content Creator and Potter
PC 7 64-bit 16gb * Intel® Core™i7-2600k Quad Core 3.40GHz * 2GB NVIDIA GEFORCE GTX 560 Ti
Cameras: Canon XF300 + PowerShot SX50HS Bridge -
You asked for some screen captures and so forth, and I can try and post those sometime soon, but in the meantime I’ll answer one of your questions.
You asked why I’m choosing YUV. Well, I’m rendering to .m2T, and as far as I can tell there is no other option with that format except YUV (it’s listed under MainConcept MPEG-2/HDV 720-30p).
What’s strange is that MainConcept AVC/Internet HD 720p is also a YUV format, but when using the Levels correction (Computer RGB to Studio RGB) the video seems to come out fine. Same goes for MainConcept MPEG-2/DVD Architect Stream. They all use YUV but Levels can pretty much correct it with two of them but not with the .m2T format.
So really, my question is more specifically with the .m2T format….how to render the still pictures so that the video reproduces the original colors.
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Brian, I’m sorry, but I’ve really had to re-edit my first post – it was full of inconsistencies and nonsense.
Ah, I can see you are asking and specifically about m2t. My apologies.
Grazie
Video Content Creator and Potter
PC 7 64-bit 16gb * Intel® Core™i7-2600k Quad Core 3.40GHz * 2GB NVIDIA GEFORCE GTX 560 Ti
Cameras: Canon XF300 + PowerShot SX50HS Bridge -
[Brian Tallant] “when I render to the .m2T format using the YUV codec”
I don’t know what this is. What Render As template are you using. It sounds like maybe something in Mainconcept Mpeg-2 since is lists .m2t in the render as dialog but what template within that encoder?
YUV codec? 99.9% of all video is YUV based, or to be technical YCbCr in digital form. Most video uses some sort of chroma subsampling and hence the need for YUV components.
[Brian Tallant] “) Is it possible to render still photos to the .m2T format using the YUV codec and produce a video that EXACTLY reproduces the color of the original image?”
“EXACTLY”, then the answer must be No.
Still camera files are in many color spaces, but lets stick with SRGB for this argument. Do not confuse this SRGB with the Studio RGB term in the video world. In HD video the color space is Rec 709. SRGB and Rec 709 use the same color primaries, but I am not sure how this applies to the reduced numeric range.Since video typically wants a numeric space of 16-235 and the still photo was 0-255, this conversion is not “perfect”. Even if you compress to 16-235 and the video player expands back to 0-255, there can be differences.
I have never tried testing anything for these small differences. I just know my initial use of stills I noticed the expansion and the Computer to studio conversion seemed close enough at least. I did not try any side by side comparison.
Also when I view stills, anything actually, on my PC I come into issues. I have a wide gamut monitor and app like the Windows 7 photo viewer and photoshop are color managed and video players may not be and I am pretty sure Vegas is not color managed. Therefore any differences I see could be due to one app being color managed and the other is not. This is very true of stills and was applicable when I compared my source still to the video after learning about the need for a level adjustment.
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Norman,
You asked what Render As template I’m using. I’m going to the MainConcept MPEG-2 category, then HDV 720-30p. If you select that template you’ll see at the top it says “Format:Video: 29.970 fps, 1280×720 Progressive, YUV, 18.3 Mbps”.
That’s what I’m using, and the resulting file’s extension is m2T.
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[Brian Tallant] “the colors do not come out the same as they were when I edited them in Photoshop”
Brian, are your monitors properly colour calibrated? I mainly output in m2t using the DVDA PAL template and include photoshopped photographs and have not noticed any colour variations.
I also output to the PAL 1080i HDV m2t template, which is also YUV, but I have not noticed any colour changes.
My system specs: Intel i7 970, 12GB RAM, ASUS P6T, Vegas Pro 12 (x64), Windows 7 x64 Ultimate, Vegas Production Assistant 1.0, VASST Ultimate S Pro 4.1, Neat Video Pro 2.6
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I have never calibrated my monitor, so no, it probably isn’t showing colors exactly right, but I only have one monitor…I edit in Photoshop, edit in Vegas, and watch the videos all on the same monitor. So the colors, even if not properly calibrated, should look the same in Photoshop as in the m2t video.
Again, this problem only seems to affect my m2t renders….mpg and mp4 have very good color reproduction.
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