Apple Final Cut Pro 7 - Manual (Page 1466)

A Common Gamma Correction Scenario
One of the most common situations that requires you to change the Gamma Level
property of a clip is when you are rendering an RGB clip within a Y
′
C
B
C
R
sequence.
Final Cut Pro uses QuickTime to import RGB media and always assumes that RGB media
(except Apple ProRes 4444) has a gamma of 1.8. When Final Cut Pro renders these clips
in a Y
′
C
B
C
R
sequence, the gamma is adjusted by a factor of 1.22 to match the 2.2 gamma
compensation required for Y
′
C
B
C
R
.
The problem with this default behavior is that RGB files are not always created with a
gamma of 1.8, even on Mac computers. In this case, you can adjust the gamma level of
your imported RGB clips accordingly.
Supported File Formats
Final Cut Pro supports gamma adjustment for the following file formats.
• Still images: JPEG, PNG, TIFF, SGI, PlanarRGB, MacPaint, and layered or flattened
Photoshop (PSD) files.
• QuickTime movie files: Movie files using the None or Animation codec
Adjusting Gamma in Imported Still-Image and Video Clips
There are two places to adjust gamma.
• Gamma Level pop-up menu in the Editing tab of the User Preferences window: This pop-up
menu globally determines gamma at the time media is imported.
• Gamma Level clip property in the Item Properties window or Browser column: You can
adjust the gamma of individual clips in the Browser or in the Item Properties window.
This allows you to override the global setting applied by the Gamma Level pop-up
menu in the Editing tab of the User Preferences window.
Choosing a Gamma Setting
Final Cut Pro analyzes imported still images and attempts to determine their encoding
format automatically. Sometimes this interpretation is incorrect. If imported still images
appear too light, or do not have enough contrast, then selecting Gamma Level 2.2 could
correct for this. Alternatively, if the images appear too dark or have too much contrast,
then this could be corrected by selecting Gamma Level 1.8.
To choose the gamma value applied to an imported file
1 Choose Final Cut Pro > User Preferences, then click the Editing tab.
2 Choose one of the following options from the Gamma Level pop-up menu.
• Source: This option uses QuickTime to interpret the gamma of imported media files.
• 1.8: Choose this option when importing media files created by an application in which
you specified a gamma value of 1.8, or created with Mac OS X v10.5.x or earlier.
1466 Chapter 85 Rendering and Video Processing Settings