Glenn ChanREELSony Vegas Tutorials

Color Spaces / Levels in Vegas 9 and 10

Vegas 8 and 9/10 handle levels differently. For Vegas 8 information, see the old Vegas 8 color spaces article.

How Vegas works

In Vegas, the levels of all your footage depend on the codec being used.

So this is what you have to do:

  1. Convert everything to either studio or computer RGB.
  2. When you render your final output, check what sort of levels the codec is expecting. You may need to convert between computer and studio RGB.

The example workflows below cover the most common situations. They also cover most of the 'gotchas' that you can run into.

Example Workflow - 8-Bit Vegas project with mostly video clips

Suppose you have DV, HDV, and JPEG images in your timeline. For 8-bit projects, I recommend converting everything to studio RGB levels.

Looking at the codec table, we see that DV and HDV both decode to studio RGB levels in 8-bit projects. We do not necessarily have to do anything to these media. However, almost all DV and HDV cameras will record illegal superwhite values above 235 RGB. You may wish to apply color correction to these clips to deal with these illegal values.

We see that JPEG images decode to computer RGB levels. Since we want studio RGB levels, we will apply the "computer RGB to studio RGB" Color Corrector (or Levels) FX preset to all our JPEG images. One way to do this is to select JPEG images in the timeline, have the Video FX window open (Alt + 8), and drag the preset from the Video FX window onto selected clips/events on the timeline.

For previewing, the Video Preview window will be inaccurate. From the codec table, we see that the Video Preview window expects/wants to see computer RGB levels. However, it is receiving studio RGB levels. So, the image it displays will be incorrect. For accurate monitoring, preview through a DV/firewire device to an external monitor. To send the video to the camera, the material has to be compressed into DV. The default DV codec (the Sony Vegas DV codec) expects studio RGB levels. We are feeding studio RGB levels, so we don't have to do anything.

When rendering the final project, we have to check to see what codec we're rendering to and what levels it expects.

If the project is for DVD or broadcast output, we should do something about the default background color (0 0 0 RGB). This is an ILLEGAL black and can cause the picture to roll on very old TV sets. To fix this, we add a solid color media generator to make a black of 16 16 16 RGB and put this onto the bottommost track in Vegas. Similarly, when we want to generate white, we need to use 235 235 235 RGB instead of 255 255 255 RGB.

Example workflow - 8-bit project with mostly still images

This is like the example above, except we convert our events into computer RGB levels in the timeline. We leave still image formats like JPEG alone, and we apply "studio RGB to computer RGB" Color Corrector FX presets to DV and HDV clips.

For previewing, we use the Video Preview window in Vegas. If this project is also for video output, then we will want to monitor on an external monitor via DV/firewire. Because Vegas' default DV codec expects studio RGB levels, we will need to apply a "computer RGB to studio RGB" levels FX onto Video Output FX to preview with the correct levels. Make sure that you disable this FX whenever rendering to a new track!!!

When rendering to codecs/formats that expect studio RGB levels, we will need to nest the project and apply a "computer RGB to studio RGB" Color Corrector FX preset.

Example workflow - 32-bit project with mostly video clips

*Life is simpler if you simply use an 8-bit project instead.

For 32-bit projects, I would recommend using the 32-bit floating point (video levels) mode and not (full range). This is the simplest approach and avoids dangerous behaviours such as forgetting to switch compositing gamma to 2.222, forgetting that the color bars decode to studio RGB, defaults into accurate previews over DV/firewire, works well with Cineform files, etc. etc. The sections on compositing gamma and levels differences between 8-bit and 32-bit projects explain why these two areas can be dangerous.

So when using "32-bit floating point (video levels)" and a compositing gamma of 2.222:

We can use a DV device as the preview device. If using a Windows Secondary Display as the preview device, make sure that the studio RGB checkbox under color management is checked under Options -> Preferences -> Preview Device.

When rendering to particular formats, it may be necessary to nest the project and apply a "computer RGB to studio RGB" preset as necessary.

(Same as for 8-bit projects) If the project is for DVD or broadcast output, we should do something about the default background color (0 0 0 RGB). This is an ILLEGAL black and can cause the picture to roll on very old TV sets. To fix this, we add a solid color media generator to make a black of 16 16 16 RGB and put this onto the bottom-most track in Vegas. Similarly, when we want to generate white, we need to use 235 235 235 RGB instead of 255 255 255 RGB.

If we want to have optically-correct compositing effects / linear light compositing, we will do this in another Vegas project and nest the resulting project into our master project. In the sub-project, use the (full range) mode and let it default to a compositing gamma of 1.000. Convert all media into computer RGB levels. e.g. convert DV and Cineform clips to computer RGB levels. Leave HDV, AVC HD media, and still images alone.

When nesting the resulting sub-project into our master project, apply a "computer RGB to studio RGB" onto that nested project/event.

Some gotchas

  1. If using video camera footage, you may want to apply color correction to deal with the illegal values above 235 RGB that almost all cameras generate. (This applies to all NLEs.)
  2. Your preview is probably inaccurate. The Video Preview window in Vegas only displays computer RGB levels correctly. It does not display pictures correctly when fed with studio RGB levels. While we are on this subject, you should understand that the Video Preview window does not really display video correctly.
    For other previewing methods, see the table of codecs if the example workflows in this article do not cover that scenario.
  3. If you are converting everything to studio RGB levels, you need to create a track of 16 16 16 RGB black as mentioned in the example workflows. Also, some of the media generators may need to be modified to produce a 235 235 235 RGB white and a 16 16 16 RGB black.
  4. If using a 32-bit project instead of 8-bit, the sections on compositing gamma and levels differences between 8-bit and 32-bit projects explain why these two areas can be dangerous.
  5. If using odd codecs, you need to verify what levels they produce and expect.
  6. If using something other than the default DV and MPEG-2 codecs, you may need to convert those clips to studio RGB.

What's New in Vegas 9 versus 8

Vegas 9 replaces the Vegas 8 behaviour for 32-bit floating point projects and instead adds two new and different 32-bit floating point modes, which I will refer to as (video levels) and (full range). Certain codecs (e.g. HDV, AVC HD) will now decode to either studio RGB for (video levels) projects or computer RGB for (full range) projects.

Compositing gamma of 1.000 is now only available in the (full range) mode.

What's New in Vegas 10

Not much.

Compositing Gamma

In 32-bit floating point (full range) projects, you can switch between a compositing gamma of 2.222 and 1.000. In "1.000" gamma, your image's values are converted from gamma-corrected values to linear light values. This does two things:

A- It gives you optically-correct compositing. Cross-dissolves will be more film-like and diffusion effects will look more correct. See the article on linear light processing in Vegas 8 for examples.

B- The 1.000 mode will cause many of the existing videoFXs to behave differently and to deliver possibly undesirable or weird results. In particular, the "Studio RGB to computer RGB" preset will no longer do what it says.

For 32-bit projects, I recommend using the (video range) mode which will disallow a compositing gamma of 1.000 and avoid any wackiness from B above. Optically-correct compositing can be achieved in 2.222 projects by nesting 1.000 projects inside them (see the linear light article for more information). However, whenever you switch to a full range project, Vegas will also set the compositing gamma to 1.000. If for some odd reason you wish to use a compositing gamma of 2.222 in a (full range) project, you will need to remember to change this back every time.

Also note that a compositing gamma of 1.000 is not available for 32-bit floating point (video levels) or 8-bit projects.

Levels differences between 8-bit and 32-bit

When you change between 8-bit and 32-bit, Vegas changes more than just the bit depth. Certain codecs like HDV (MPEG-2) and 10-bit SonyYUV will decode to different levels depending on your project properties setting.

In 8-bit, these codecs will decode to studio RGB levels.
In 32-bit floating point (full range), these codecs will decode to computer RGB levels.
In 32-bit floating point (video levels), these codecs will decode to studio RGB levels.

*See the article on color spaces in Vegas for a primer on studio RGB versus computer RGB levels.

Changing the project properties may cause changes to your video's levels. Also be careful with the (video levels) mode since it will default the compositing gamma to 1.000, which will also cause color changes. Certain footage in 32-bit projects may look "better"/different, but this is only because the levels are being decoded differently.

However, not all codecs are affected by project properties. Codecs like DV and Cineform do not have this behaviour- they decode to the same levels regardless of project properties. These codecs and Vegas' Color Bars generator will need to be converted.

The interaction between particular codecs and project properties can be an issue when rendering or previewing via DV passthrough. When previewing through a DV device, Vegas' DV codec will want to see studio RGB levels. In (full range) mode, HDV footage will decode to computer RGB levels, which is inappropriate for Vegas' DV codec. In that situation, the preview will be incorrect.

Please see the example workflow sections at the bottom of this article for suggested workflows.

Table of Codecs

The following table describes the behaviour of various codecs and preview methods. It also indicates whether the codec behaviour changes in 8-bit and 32-bit/(video levels) versus 32-bit/(full range) projects.

Name of format / codec In 8-bit projects and 32-bit/(video levels) In 32-bit/(full range) projects
AVC HD via Main Concept MPEG-4 (Vegas' default MPEG-4 codec)

Studio RGB. (Decodes to and wants to see studio RGB levels.)

Computer RGB. (Decodes to and wants to see computer RGB levels.)

HDV, Main Concept MPEG-2 (used for DVD encodes out of Vegas)
Sony YUV, 10-bit Sony YUV
Cineform (captured through their tools) Studio RGB. (Decodes to and wants to see studio RGB levels.) *Some versions of Cineform allow you to change the preferences/settings so that it decodes to and expects computer RGB levels. However, the default for Cineform in Vegas is studio RGB.
Vegas DV codec Studio RGB. (Decodes to and wants to see studio RGB levels.)
Third party DV codecs Depends on codec. May use computer RGB or studio RGB levels.
Still images (e.g. JPEG, PNG, GIF) Computer RGB. (Decodes to and wants to see computer RGB levels.)
Windows Media (from within Vegas, not within Windows Media Encoder)
Uncompressed (8-bit); rendering to "uncompressed" / Video for Windows AVI from an 8-bit project Passes levels through. Will decode to whatever levels it receives. e.g. If you feed the codec studio RGB levels, it will decode to studio RGB levels. If you feed the codec computer RGB levels, it will decode to computer RGB levels. Passes levels through. Cannot encode 8-bit uncompressed from 32-bit project.

Uncompressed (32-bit); rendering to "uncompressed" / Video for Windows AVI from a 32-bit project

Not to be confused with Aja/Blackmagic/Apple/Quicktime uncompressed codecs.

Passes levels through*. Cannot encode 32-bit uncompressed from 8-bit project. Passes levels through*.

*There seems to be a bug if rendering to this format from a project with 1.000 compositing gamma (in Vegas 8, this occured with a compositing gamma of 2.222). The encoded values seem to have a significant gamma shift (a Levels FX with a gamma of 2.222 seems to undo this).

Quicktime codecs (via Quicktime import/expect from Vegas) The majority of codecs use computer RGB. (Decodes to and wants to see computer RGB levels.) But not all codecs do this.
DVCPRO HD via Raylight ?Studio RGB? (I have not checked personally.)
Default background 'Decodes' to computer RGB. The default background color is 0 0 0 RGB, which is an ILLEGAL black and inappropriate for codecs that expect studio RGB. Fix this by adding a solid color media generator that creates a 16 16 16 RGB black for studio RGB codecs.
Color bars media generator 'Decodes' to Studio RGB.
Red / R3D files

Decode to studio RGB levels. The Brightness and Contrast settings in the R3D Decode Properties window can cause illegal values below black.

Setting the DRX setting above 0 will recover highlight detail and create superwhites / values above white level.


Preview Method In 8-bit projects and 32-bit/(video levels) In 32-bit/(full range) projects
Video Preview window Computer RGB. (Wants to see computer RGB levels.)
via DV device (e.g. camcorder); using Vegas DV codec Studio RGB. (Wants to see studio RGB levels.)
via DV device (e.g. camcorder); using third party DV codec Depends on whether the 3rd party codec uses computer RGB or studio RGB levels.
Windows Secondary Display May use computer RGB or studio RGB levels. The setting is under Preferences -> Preview Device (tab) -> Color management (checkbox) -> Use Studio RGB (16 to 235). If the Use Studio RGB checkbox is active and checked, the windows secondary display will want to see studio RGB levels.
Aja Video Device ?Studio RGB? (I do not know.) ?Computer RGB? (I do not know.)

If the preview display/method is fed with values of the wrong color space/levels, then it will display an inaccurate image. This can be ok as long as you know that the preview is inaccurate (if you do not need a 100% accurate preview, e.g. for rough edits).

 



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