Chapter 20, Color Correction
| Working with ASC CDLs | |
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Transforming Color Space with the Log and Delog Tools |
Chapter 20, Color Correction |
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When working with material that is intended for television broadcast, the Broadcast Safe Colors tool ensures the images in your composites translate well (and safely) to a television display.
Since most computer monitors and television displays have different color ranges, the same image on a computer display can appear very different on an NTSC or PAL monitor.
Colors appear much brighter on a television display. This is because video uses a different gamma curve for luminance than a computer monitor. Also, most computer monitors use RGB color space, and television displays use YUV color space.
Some pure colors, such as red and yellow, can cause bloomed (very saturated, fuzzy) images. In some cases, colors can cause interference with broadcasting, which is referred to as NTSC illegal colors.
The Broadcast Safe Colors tool automatically reduces the luminance or saturation of portions of the image, or isolates unsafe or safe colors that you can then adjust manually.
 "Show full-size image")
| Select: | To: |
| Format | Set the unsafe colors as NTSC or PAL. |
| Method | Determine how the unsafe colors will be fixed, or identify the colors so you can fix them. |
| Max Signal Amplitude | Adjust the video signal amplitude, where 120 is maximum, and 90 is the minimum. The default amplitude is 110. |
| Replacement Color | Click to select the replacement color from the color picker. Then click Set. |
From the Tools tab, drag the Broadcast Safe tool from the Color Correction folder to the dependency graph in the Schematic view.
From the Format list, select NTSC or PAL (your video format).
From the Method list, select one of the following:
| Select: | To: |
| Reduce Luminance | Automatically reduce the luminance of the offending portions of the image to broadcast legal. Use Maximum Signal Amplitude to adjust the limits of the luminance. Note: The Maximum Signal Amplitude should be limited to 110. |
| Reduce Saturation | Automatically make any overly saturated portions of the image broadcast legal. Use the Maximum Signal Amplitude to adjust the limits of the saturation. |
| Key Out Unsafe | Cut out the unsafe colors from the image, leaving only the safe color regions. |
| Key Out Safe | Cut out the safe colors from the image, leaving only the unsafe color regions. |
| Replace Color | Fill the unsafe portion of the image with the selected color. |
Note: Use the Key Out Unsafe and Key Out Safe options to see any problem colors in your image immediately. For example, you can fix the problems in the Color Corrector by adding the output of the Broadcast Safe tool as the masking input to the Color Corrector.
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