Added constrast when project rendered

[Dave Brytus]

Does anyone know why sony vegas adds contrast when a video is rendered? Footage looks great in sony vegas but when i render it has alot more contrast. Is there a way around this?

[Phil Lee]

Hi

Sounds like a levels issue.

By default the preview window (and second monitor preview) has computer levels, this means viewing typical HD footage will display it looking a bit washed out, then on rendering it will look more contrasty. This might might you think Vegas is adding contrast.

What is the source of your footage, have you applied any other filters?

Regards

Phil

[Dave Brytus]

The footage is coming from a 60d and a gh2 so H.264 and AVCHD. I think i might have fixed the problem. I just add a levels filter (compter to studio RBG) before I render. Is that what you would suggest doing? Or is there a way you can change the preview monitor to display differnt levels?

[Phil Lee]

Hi

It depends what you are rendering back out to as well.

If you are using a second monitor then to make that correct go to Options-Preferences-Preview Device and select 'Use Studio RGB (16 to 235)', this makes the second monitor match the output in terms of levels. The smaller windowed preview you can't adjust in this way and it will usually be wrong.

H264 on the time line is already studio level, so you shouldn't require a level shift again to studio levels.

One test is to watch the original footage in Windows Media player (if using a PC) then to watch your output and look for shifts in the level, they should be the same.

Regards

Phil

[Dave Brytus]

Your right when i import the footage into vegas the colors have less contrast. When I render out, it looks the same as the source file when i open it in windows media player.

How can I get my preview monitor in Vegas to show exactly what I am going to render out too? If vegas takes contrast away when I import the footage then I want it to render that way! This is such a pain when I am color grading! My final output will be mp4 for youtube, vimeo, and other computer related viewing.

[Dave Brytus]

Ok nevermind....Vegas is accurate....Its actually Windows Media Player that shifts the levels....I opened the same file in VLC media player and it matches the rendered file with the Vegas monitor perfectly!

[Phil Lee]

Hi

Unfortunately it isn't that simple :-(

Windows Media Player knows the video file has RGB levels of 16-235 and without adjustment this displays incorrectly as on a PC which uses 0-255 then 16 for black in the video is actually dark grey and not true black, white at 235 is a light grey and not white. So Windows Media Player makes a level adjustment so that the video is displayed correctly, matching how the video would be seen level wise on a TV as well.

VLC doesn't do this level adjustment, so like Vegas, you have what looks like less contrast. VLC and Vegas have incorrect levels by default.

So to sum up, to get the video levels looking correct, on a PC monitor you have to make a level adjustment, Windows Media player is showing you the video with the correct levels as it is making this adjustment, VLC and Vegas aren't.

Regards

Phil

[Federico Perale]

on this topic can I just ask what's the procedure when I have different types of files in the same timeline, as in the case of the original poster?
for instance AVCHD (which requires adjustment) and h264 mp4 (which doesn't)?

shall I still use the Computer to Studio RGB plugin? don't I run the risk that the h264 portions of the final video will have a lower contrast than meant to be?

[Jerry Amende]

I'm deleting this post, because I'm seeing some unexpected strangness in Sony Vegas 11. I'll repost when I figure it out.

...Jerry

[Jerry Amende]

Originally Posted by Federico Perale

on this topic can I just ask what's the procedure when I have different types of files in the same timeline, as in the case of the original poster?
for instance AVCHD (which requires adjustment) and h264 mp4 (which doesn't)?

shall I still use the Computer to Studio RGB plugin? don't I run the risk that the h264 portions of the final video will have a lower contrast than meant to be?

Okay, I've sorted out the "strangeness" I thought I saw in Vegas 11.

The cRGB->sRGB Levels FX should be used based upon the levels (rather than the format) of the footage on the time line, the render format and the player involved. For example, it doesn't make any difference what the format of the source footage is, if it is outside the 16-235 range and you are playing it in a format/player that expands these levels.

Here's an example, the numbers in the panels are the Levels as placed upon the Vegas time line. Since an mp4 render/Flash Player expands the levels, if you don't apply the cRGB->sRGB Levels FX, the left side will look entirely white, whereas the right side will look entirely black. Once the cRGB->sRGB is applied, you should properly see levels of white & black.

Nick Hope Levels Test - Vegas 11 on Vimeo

How do you know if your player/render expands the levels? I use the following Vegas 11 test project and see how my see how the render works: http://www.jazzythedog.com/sharing/NH-V11.zip

Another example: if you render to wmv & play in WMP, then the levels do not expand.

Make sense?
...Jerry

PS: Thanks to Nick Hope of the SCS forums for coming up with this concept.

[Magnus Helander]

Thank you Jerry, there cannot be any better way to explain it
/m

[Danny Fye]

Originally Posted by Jerry Amende

Another example: if you render to wmv & play in WMP, then the levels do not expand.

If I render to wmv from Vegas the black level will be raised up reducing the contrast.

[Phil Lee]

Hi

Once the cRGB->sRGB is applied, you should properly see levels of white & black.

In the example proper levels for White and Black are not being seen, they've just been crushed so they are now visible for codecs that are typically studio level. If the footage is really computer level, i.e. blacks are 0 and white is 255, then the conversion to sRGB has lost picture information. You have no choice but to do this for DVD/Blu-ray that will be played back on a TV (or similar codecs that on a PC are treated as studio level by default), but if your target is online/computer playback you might want to look at other options. See next point.

If I render to wmv from Vegas the black level will be raised up reducing the contrast.

This is because WMV is a computer level codec, it is by default working in the 0-255 space. For WMV to have the correct levels then black should be at 0 and white at 255. If your source footage is already 0-255, you don't need to do any level adjustment. If your source footage is video, so black is 16, it needs to be stretched out to fill the entire 0-255 space, so that black is black you need a sRGB to cRGB (studio to computer) level adjustment in Vegas, this stretches out the 16-235 so now white is 255 and black is now 0 and it will look good on your computer screen.

WMV is a great choice for computer playback especially where your footage is already 0-255, as you don't lose any picture information. Quicktime is also 0-255.

Note that level conversion is lossy in certain directions. As soon as you apply a computer to studio level shift, regardless what the original footage really is, you have lost picture information. This is because 0-255 is squeezed into 16-235, clearly you haven't enough values in 16-235 to store all the values from 0-255, hence the loss. You can convert it back to computer level, and it might look okay, but make no mistake, there is less picture information than before.

As for a mixture of levels on the timeline, then decide what level you are going to work with. If you have lots of video, stick with studio level, if you have lots of images, stick with computer level. Then if your footage is opposite to you what you are working with, shift the level using a level filter on the clip as appropriate so it matches the rest, that is the key, all clips should be at the same level, converted if necessary. Typically video is always studio level, and photos are usually computer level. See this link for more info: Color spaces and levels in Sony Vegas 9 and 10

When you come to output then make sure you output at the correct level:

So outputting for DVD/Blu-ray/AVC/MPEG2 which are studio level, then you need to send them studio level video, if your timeline is working in studio level already, you don't need to do anything, if you are working in computer levels, add an overall computer to studio level filter.

If outputting for WMV or Quicktime which are computer level, make sure you output at computer levels, if you are working on the time line already in computer level, no need to do anything, if it's studio level, then add an overall level filter to convert studio level to computer level.

Remember the note about level conversion being lossy? If your output is going to be computer level, and you have computer level footage mixed with studio level footage, then you are better off having a timeline in the computer level colour space, this means your computer level footage with values from 0-255 isn't being crushed into the 16-235 video level space only to be expanded again on output, which of course results in lost information.

Also note that the Vegas preview window shows you the footage as it is, and not what you will get. So if you have video level footage on the timeline, it will look somewhat washed out in the preview window, with computer level footage looking good. If you add a studio to computer level filter on a video clip, the preview window will then show the video footage looking good (the preview window is computer level), and you may think your levels are fine, but if you output to a studio level codec such as AVC or MPEG2 it will look too contrasty on playback.

Hope that helps.

Regards

Phil

[Peter Riding]

As for a mixture of levels on the timeline, then decide what level you are going to work with. If you have lots of video, stick with studio level, if you have lots of images, stick with computer level. Then if your footage is opposite to you what you are working with, shift the level using a level filter on the clip as appropriate so it matches the rest, that is the key, all clips should be at the same level, converted if necessary. Typically video is always studio level, and photos are usually computer level.

Phil, what would be your recommendation where the show contains a significant amount of both video clips and stills? For DVD shows I have the stills on a separate track (or 2 or 3 tracks if there are various fade ins of multiple stills to appear within the same set of frames) above the video tracks. I do a track conversion from computer to studio RGB for all the video tracks and then a track curves adjustment to the Stills tracks to lessen the contrast in the stills. If I were to do a computer to studio RGB conversion on the Stills tracks then in instances where the frames contain more than one Still and the background is black, then as soon as the 2nd Still appears the background noticably jumps to dark grey. Probably a compositing issue I need to get around. Oh, I also use Nesting quite a bit, typically placing 3 to 5 projects into the final show by dragging and dropping each of the .veg files into their own track.

Cheers.

Pete

[Phil Lee]

Hi

The jump in black level is because by default Sony Vegas black is 0, so anything showing through to nothing or using a black mask is at RGB 0,0,0, but studio level black is 16, 16, 16. If you are working with a studio level time line then black should really be 16,16,16. The problem with adding a computer level image especially if you pan and crop it so you leave black, then do a studio level convert, any black in that clip is, quite correctly, converted to 16,16,16. Now if you have panned that clip, so the default Sony black is showing through from tracks below, you of course see a border of black and dark grey.

If you render out to a studio level codec, such as MPEG2 or AVC, that rendered video contains black at 0,0,0 (the Sony default black and black at 16,16,16. Now because it is a video type codec, the TV or software player should cut out everything below 16, and everything above 235, then stretch the remaining 16-235 values up to 0-255, the result then is the 0,0,0 black and the 16,16,16 black all end up at 0 and you don't see the two different shades of black in the final ouput, however this very much depends on the player, the player may decide that because there are values lower than 16 the content isn't at video levels so it shouldn't top and tail the RGB values and stretch them, so you end up with a visible difference in some black levels.

A easy solution is at hand, if you go to Sony Vegas Color Correction Tutorial and download the Vegas project under the heading "The Curves Method of Colour Correction". When you open this project, the first clip contains a filter that removes illegal levels from studio footage, open the filter, type in the preset a meaningful name and save it, now you can use it in your own projects.

Now on the Video Bus track, (View menu then make sure Video Bus Track is selected and it appears at the bottom of the time line) you add this new filter. Click add filter, and add a Sony Color Curves filter, in the preset drop down select the name you used to save it. This filter makes your timeline legal for studio colours, blacks lower than 16,16,16 become 16,16,16, and whites above 255 become 235. You will now see the Vegas black becomes dark grey to match the studio level shifted images. Remember if using the Sony Vegas preview and a studio level time line, black will always show as dark grey because the preview window using computer levels. That should solve your problem.

So to sum up, the problem is with Sony Vegas and it's default 'black' or nothingness is a computer level black, using the filter above forces the Sony Vegas black into a studio level black of 16,16,16 for time lines at studio level. Hope that helps.

Regards

Phil