Going Color Crazy

[Angelo Mike]

I’ve only recently started studying and dealing with these issues, but my assumption on projects for DVD or broadcast so far has been to adjust color curves and color correct first, then convert from computer to studio rgb at the track level. I’m just assuming that doing it the other way around would bring the colors back out of the studio rgb range.

I shoot on a similar camera and make a lot of videos for Youtube, and I never convert from computer to studio rgb. I’ve never heard of people doing that. I don’t know if people do that, but in my experience, video looks exactly (well, almost, given Youtube’s recompression) how it should online in 0 to 255. But I just don’t know if anyone has said otherwise. I haven’t seen it on any tutorials that I occasionally watch on how people render for the internet.

http://www.scenethroughglass.com

[James Dubendorf]

Mike,

My understanding about color issues with streaming video comes from here

https://www.bubblevision.com/underwater-video/YouTube-Vimeo-levels-fix.htm.

and here

https://www.youtube.com/watch?v=rWMX5lSvEgY

If you engage the computer to studio fx at the track level, you can always toggle it on and off as you edit at the event level within the track. I suppose that is personal preference. What you would not want to do is convert computer to studio at the event level (using whatever fx combination), then do that again at the track level- if you look at the histogram, this would squash it far within the boundaries of 16-235. You could (in theory) convert at the event level, then apply the broadcast filter at the track level to catch any stray bits- this simply cuts of illegal colors rather than compressing the spectrum.

James

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[John Rofrano]

[Angelo Mike] “I never convert from computer to studio rgb. I’ve never heard of people doing that. I don’t know if people do that, but in my experience, video looks exactly (well, almost, given Youtube’s recompression) how it should online in 0 to 255.”

Did you look at the link that James provided? This is absolutely required because YouTube will blindly change your luminance levels if you don’t. The proof is in the link which shows the original screen capture before, and then how YouTube crushed the blacks and whites after.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[John Rofrano]

[James Dubendorf] “At this point, a question about the scopes settings: am I correct that the scopes settings alter what is shown on the scopes, but not the image in the preview window?”

Yes. This is an important observation. Editors make the mistake that these settings actually change the video. They do not. They only change the setup for the scopes.

[James Dubendorf] “Also, am I correct that the scopes analyze the file and not the display device, so even a monitor with horrible color settings would still have scopes that were accurate?”

Yes that’s correct. It is showing you the data in the video regardless of how bad your computer display might be calibrated.

[James Dubendorf] “With both scopes settings boxes unchecked, can I be confident the scopes are an accurate representation of the file itself? There seems to be differing opinions on whether a camera such as the vixia works in the studio or computer color space.”

Yes, that’s correct. The purpose of the Studio RGB setting is to convert 0 to 100 to equal RGB 16 to RGB 235. It just makes it easier to read the scopes.

[James Dubendorf] “Convert that file through neoscene, and it becomes an avi described by Vegas as 1920x1080x24 (I assume the shift from 12 to 24 indicates an improvement to the color space of the file post conversion?). It also falls outside the studio color space according to the histogram”

Converting it to CineForm should not change any scope readings. The video data should remain the same because CineForm does not change the video data in any way (other than convert to 4:2:2 color space)

[James Dubendorf] “Ah, and another thing. In the preview device preferences, I’ve left “convert display from studio to computer” unchecked based on this logic: my files are computer color space, and I am viewing them in the preview window of my external monitor running off my computer. Why convert them from studio to computer if they are already computer. Is this correct?”

The purpose of the preview is to see what your video will look like on your target device. If you are authoring for DVD, Blu-ray, or TV Broadcast, I would keep Adjust levels from studio RGB to computer RGB turned on as these devices use Studio RGB. If you are authoring for the Internet, I would keep this turned off as these devices use Computer RGB. This setting has nothing to do with the footage your camera shoots.

[James Dubendorf] “My understanding is that the computer to studio conversion must occur regardless of whether the file is destined for broadcast, DVD, bluray, or most web streaming. Even though computers work in 0-255, almost any way of streaming video requires the file to be in 16-235. The goal, therefore, is to have the colors you see in the Vegas preview window be essentially identical to what you see on youtube or vimeo. “

Not for DVD or Blu-ray if your source is already Studio RGB (like DV or HDV). DVD and Blu-ray are Studio RGB devices so no conversion is needed if your source is already Studio RGB. The Internet is a computer device but here is the subtle problem that you might not have gotten from the links you posted.

The problem is not so much Studio RGB vs Computer RGB. The problems is that video sites like YouTube and Vimeo boldy assume that your video is Studio RGB so they BLINDLY (and sometimes wrongly) convert all videos from Studio RGB to Computer RGB whether they need the conversion or not. In effect, what you need to do always make sure that you supply sites like YouTube and Vimeo with Studio RGB video even if your video is Computer RGB already because they will convert them whether you like it or not. That is different from using a streaming site that does not blindly convert, in which case you should deliver Computer RGB video.

[James Dubendorf] “While the broadcast colors fx in Vegas simply chop off anything outside the studio color space, the computer to studio and studio to computer fx appear to compress or expand them. Compression is better than chopping, right?”

Yes. We call it clipping and clipping is bad. It could turn parts of your video featureless which will get your tape rejected by most broadcast stations (if you are going to broadcast).

[James Dubendorf] “It would seem that before beginning color correction, you would need to decide what level to manage the computer to studio conversion- event, track, video output fx, some combination of those, etc.”

Well… whatever you descide you need to be consistent, and I would let the nature of your source video be the guide.

[James Dubendorf] “My plan is to implement the computer to studio conversion at the track level. This will establish the limits of 16 to 235 of every event in the track. Then, I will adjust curves, color corrector, etc. at the event level. Does this sound reasonable?”

I would only do that for tracks that contain nothing but images. I would not add it to the camera tracks unless you are certain that the are in Computer RGB. At that point, just add it to the Master Video Bus if everything in your project is already Computer RGB.

[James Dubendorf] “If I do this, should I still check 7.5 IRE and Studio in my scopes settings?”

You should not check 7.5 IRE, you should check Studio RGB to make it easier to read the scopes.

[James Dubendorf] If I’ve already set my limits with the computer to studio conversion at the track level, and I know I can’t exceed those at the event level, isn’t it a matter of personal preference?”

Don’t confuse the setup on the scopes which do nothing to your video, to a filter which is altering your video. So it’s not personal preference. You use the scopes to see if your video is legal, you use the filters to make it legal when it’s not, the two are separate settings.

[James Dubendorf] “Oh, and one final question. I believe it was in one of John Rofrano’s posts where I read that the sony avc assumes it is receiving studio color space, and converts it to computer. Indeed, when I drop an AVC file into the Vegas timeline, the histogram confirms it is 0-255. Does this mean that a file in computer color space converted into sony avc will always lose its edges? “

No, you will not loose anything. The Sony AVC encoder will output exactly what you give it. I was fooled by the Windows Media Player which performs some kind of conversion on AVC files in general. If you drop them back in Vegas or view them with QuickTime, they will look normal. Be very cautious of which media player you use because some will convert the levels on the fly (not good) 🙁

[James Dubendorf] “To whomever has read this far, many thanks for bearing with me. I appreciate any thoughts or comments about where I’ve gone right or wrong.”

I’m still here. 😉

~jr

http://www.johnrofrano.com
http://www.vasst.com

[James Dubendorf]

John,

Many thanks for your extremely helpful response. When I wrote my first post, I had no idea the amount of discussion these issues had inspired on forums like this:

https://www.sonycreativesoftware.com/forums/ShowMessage.asp?MessageID=754200

I don’t have the technical background to fully understand this stuff (even the very well informed appear to have different views!), I don’t have the time to stop everything and earn multiple degrees, and my work simply does not demand (nor will my clients be interested in paying for) the highest levels of color correction and fidelity. I am simply trying to formulate a survival strategy that will let me live to film and edit another day!

All the files I’m working with, be they still images or avchd files, are in computer rgb (more on that in a second), so these comments apply to a workflow based on that fact. Also, my projects, though relatively short in length, typically contain numerous short events- therefore anything that has me working event by event is fairly time consuming.

My conclusion is that there appears to be considerable value in being able to render the same video file in both computer and studio color spaces. Youtube or Vimeo can suddenly change their process, new streaming options can come along, you might suddenly have to produce a version on dvd, etc. It seems that the higher up the chain one goes from event to video output fx, the easier it becomes to switch between spaces as long as all track events exist together in the same color space.

This ALSO assumes that if you are converting from computer to studio rgb, you are content with how Vegas applies clipping or compression uniformly to everything depending on the particular plugin and settings.

And here’s the rub. Many of the still images and movie files exist, for lack of a better description, “in between” computer and studio rgb on the histogram. In other words, some would lose crucial detail if 0-16 and/or 235-255 was clipped rather than compressed (or “mapped,” as this tutorial puts it: https://www.glennchan.info/articles/vegas/color-correction/tutorial.htm). Some would look fine if one end was clipped but not the other. Some look just fine with both ends clipped, and horrible if they are compressed. The question of compression, clipping, or some mix of the two, sometimes has to be answered at the event level.

If I’m not entirely off base so far, one could in theory clip at the track or even video output fx level to establish legal boundaries, and then decide how much and which part of the histogram to include within those boundaries at the event level. Or simply make all these decisions piece by piece at the event level.

I’m worried, however, that I’m not entirely understanding the rgb conversion tool. In almost all cases, applying computer to studio rgb conversion obviously makes my images look washed out in the preview window on my external LG led monitor hooked up to my laptop. You hate to give up computer rgb! In many cases, clipping looks a lot better than compressing.

I’ve experimented with turning on and off the “adjust levels from studio to computer rbg” option in preferences-preview device. It makes no apparent difference in my preview window. Should it? And if so, am I not seeing the conversion correctly?

Perhaps my question is this: are the levels problems introduced by conversion from computer to studio an exposure of levels issues that were already existing in the event BEFORE the conversion, or does the conversion create its own problems even on a perfectly tuned event?

If its the former, one could rest easy as long as the levels were sound before the conversion. Color correct and adjust levels in computer rgb at the event level, then throw a conversion on the whole project when needed. If its the latter, you are pretty much left with no choice but to edit two separate versions of the same project going event by event. That’s a lot of work.

Well, its late and I might well be over-thinking this. Heck, my videos were serviceable even before I knew levels or color correction existed.

Thank you for your time!

James

[John Rofrano]

[James Dubendorf] “If I’m not entirely off base so far, one could in theory clip at the track or even video output fx level to establish legal boundaries, and then decide how much and which part of the histogram to include within those boundaries at the event level. Or simply make all these decisions piece by piece at the event level. “

You’re correct. What I like to do is keep each camera on it’s own track and correct at the track level. Then I’ll go back and adjust any events that may be out of limits but usually there are very few. Events from the same camera usually need the same correction (unless you have drastic scene changes like indoors and outdoors)

[James Dubendorf] “I’m worried, however, that I’m not entirely understanding the rgb conversion tool. In almost all cases, applying computer to studio rgb conversion obviously makes my images look washed out in the preview window on my external LG led monitor hooked up to my laptop. You hate to give up computer rgb! In many cases, clipping looks a lot better than compressing. “

It doesn’t matter it looks washed out. YouTube and Vimeo are going to expand it back out again and it will look fine. If you didn’t do this, your video would look too dark.

[James Dubendorf] “I’ve experimented with turning on and off the “adjust levels from studio to computer rbg” option in preferences-preview device. It makes no apparent difference in my preview window. Should it? And if so, am I not seeing the conversion correctly?”

These options only affect the Secondary Preview. Not the little preview window.

[James Dubendorf] “Perhaps my question is this: are the levels problems introduced by conversion from computer to studio an exposure of levels issues that were already existing in the event BEFORE the conversion, or does the conversion create its own problems even on a perfectly tuned event?”

We are discussing two things here. (1) keeping your video within the proper levels which happens before the conversion. (2) Tricking YouTube and Vimeo into displaying the proper levels. They are separate and distinct problems. Even if you didn’t have the second, you would still have the first. The conversion in (2) does not cause it’s own problems.

[James Dubendorf] “If its the former, one could rest easy as long as the levels were sound before the conversion. Color correct and adjust levels in computer rgb at the event level, then throw a conversion on the whole project when needed. If its the latter, you are pretty much left with no choice but to edit two separate versions of the same project going event by event. That’s a lot of work. “

It’s the former.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[James Dubendorf]

John,

Ah! Thank you! The appearance of the image in my preview window after the conversion is not how it will “actually” look when displayed on youtube, vimeo, or even on dvd. This simple misunderstanding has led me down such a confusing road! I assume it is also true that the appearance in the preview window of a computer rgb video in computer rgb color space with its ends clipped (0-16, 235-255)is not how it would ultimately look in youtube, vimeo, etc.

Unfortunately, though my video is all from the same camera, there is tremendous variation between tracks- inside, outside, dark, bright. I will have to tailor my workflow to this consideration.

My attempt to summarize:

CHOICE 1: What color space do I edit in?

The goal here (at least for me) is to use the preview window (as opposed to secondary preview) as a somewhat reliable guide for color correction and levels. If editing in computer rgb, no problem. If editing in studio rgb, you must apply a studio to computer conversion at the video output fx level while editing so that the preview window is not grayed out. Most of the time, it is probably easiest to edit in the color space that matches the majority of the content. What you do NOT want to do is convert twice in the RENDER (i.e. make each event legal at the event level, then apply another conversion at video output fx).

Choice 2: What color space do I render in?

It seems to me there are advantages to having the capability of rendering to either computer or studio rgb- different jobs, different requirements. As long as you’ve done all your editing in the same color space, this is a fairly straightforward conversion as a video output fx.

Do you think I’m starting to get a handle on all this?!

Once again, many thanks for your help John.

James

[John Rofrano]

I did some more digging and from what I’ve read, AVCHD (which your camera shoots) is a YUV codec and therefore what Vegas calls “Studio RGB”. So you do not have Computer RGB footage from your camera.

There is a great article by Glenn Chan that explains the workflows in Vegas Pro 9 & 10 (and 11 although he wrote this before Vegas Pro 11 was released) Read the sections titled “Example Workflow – 8-Bit Vegas project with mostly video clips”.

Color Spaces / Levels in Vegas 9 and 10

You should do all of your color correction in Studio RGB and don’t need to apply any conversion when going to DVD, Blu-ray, YouTube, or Vimeo because they all expect Studio RGB. You would apply Studio RGB to Computer RGB when rendering to formats like QuickTime that expect Computer RGB

~jr

http://www.johnrofrano.com
http://www.vasst.com

[James Dubendorf]

John,

I had read Glenn’s post before, but for some reason it is only now coming together for me.

His post is largely in agreement with this one, though they approach from different directions:

https://techblog.cineform.com/?p=2959

Let’s assume avchd footage from the canon vixia hfg10 is native YUV. According to this post, these files will indeed contain values below 16 and above 235, but black is at 16 and white at 235. When these files are converted to rgb (i.e. windows media player), they are supposed to be converted 16 to 0 and 235 to 255. The values outside the legal range are discarded, BUT this has no effect on the image itself. This makes intuitive sense to my experience. I drop an avchd clip into the vegas timeline, or a neoscene avi of the same file (YUV 4:2:2 encoded format). Apply broadcast color lenient -7.5. The histogram confirms the illegal edges are clipped, but I notice NO CHANGE in the image in the preview window.

Again, according to the cineform blog post, if the video is to be accurately viewed in the vegas preview window on a computer monitor for the purposes of levels and color correction, it must be converted from studio to computer rgb. Glenn does not mention this option specifically, but does acknowledge the need for it. You must remember to turn this off before the render.

So…

Applying broadcast colors to avchd or avi files in preview and render: fine, probably helpful.

Converting those files computer to studio rgb for render or preview: bad.

Converting those files studio to computer rgb for rendering to formats like quicktime: good.

Converting those files from studio to computer for color and levels correction in the preview window but NOT render: good for most things like dvd, bluray, most streaming video, etc.

Converting still images, text, computer generated backgrounds, etc. from computer to studio rgb in this workflow: good.

So, after all my torment, I think I just repeated what you said!

Thanks again, John. I think I am starting to understand this stuff. Famous last words…

James

[Tyson Onaga]

OK, now I’m a little confused:

[James Dubendorf] “My understanding is that the computer to studio conversion must occur regardless of whether the file is destined for broadcast, DVD, bluray, or most web streaming. Even though computers work in 0-255, almost any way of streaming video requires the file to be in 16-235. The goal, therefore, is to have the colors you see in the Vegas preview window be essentially identical to what you see on youtube or vimeo. ”

[John Rofrano] […snip…] The problem is not so much Studio RGB vs Computer RGB. The problems is that video sites like YouTube and Vimeo boldy assume that your video is Studio RGB so they BLINDLY (and sometimes wrongly) convert all videos from Studio RGB to Computer RGB whether they need the conversion or not. In effect, what you need to do always make sure that you supply sites like YouTube and Vimeo with Studio RGB video even if your video is Computer RGB already because they will convert them whether you like it or not. That is different from using a streaming site that does not blindly convert, in which case you should deliver Computer RGB video.

and from this thread: https://forums.creativecow.net/thread/24/939771

[John Simmons] “Do I need to apply the Sony Levels Studio RGB to Computer RGB?”

[John Rofrano] The answer unfortunately, depends on what codec you are using. If you render to Sony AVC using one of the Internet HD … templates, then you don’t need to do anything. The Sony AVC codec assumes you are feeding it Studio RGB and it will convert it to Computer RGB for you. So you don’t have to do anything. I’m not sure about MainConcept AVC because I don’t use it much. The bottom line is to feed the codec what it expects.

And Glenn Chan’s article: https://www.glennchan.info/articles/vegas/v8color/vegas-9-levels.htm

From this, to create a video for YT/Vimeo, I would place the Sony Color Corrector on the Main Video Bus and set it to Computer RGB to Studio RGB.

1. So will the Sony AVC renderer convert it back to Computer RGB?
2. If it does, wouldn’t that contradict the objective above (to supply YT/Vimeo with a Studio RGB video)?

I’m relying on the wisdom of John and Glenn (and other like them) here …
Thanks.