Apple Compressor (4.0) - Manual (Page 159)

Chapter 7 Advanced functions 159
Gamma Correction
Controls the overall brightness of an image as displayed on a monitor by changing the gamma
amount of the media file. This filter can be used to remove detail from an underexposed clip or
reduce an overexposed clip’s saturation to an acceptable level without washing out the image
too much. Computers using different operating systems have different monitor settings. For
cross-platform viewing, correcting the gamma will improve the image for all platforms.
The Gamma Correction filter contains a single control:
•
Gamma: Sets a gamma setting between 0.1 and 4.0.
Letterbox
Scales and positions the image in the frame within horizontal letterbox bars.
The Letterbox filter contains the following controls:
•
Type: Choose a letterboxing method from this pop-up menu. Scale vertically compresses
the video to fit within the letterbox bars. Matte crops off the video where the letterbox bars
are placed.
•
Position: Choose the position of the video from this pop-up menu. Center places letterbox bars
above and below the video, keeping the video centered. Bottom positions the video at the
bottom of the screen with a single letterbox bar above it. Top positions the video at the top of
the screen with a single letterbox bar below it.
•
Output: Choose the specific aspect ratio to use for the letterbox from this pop-up menu. Each
menu item is followed by a value that shows the ratio of the width to the height for that
setting. For example, the Academy setting shows its aspect ratio as 1.85:1, indicating that the
image’s width is 1.85 times the size of its height. The Manual setting enables the Manual slider,
which you can use to manually set the letterbox aspect ratio.
•
Manual: Lets you manually set the letterbox aspect ratio when Manual is selected in the
Output pop-up menu. (The Manual slider has no effect when Manual is not selected in the
Output pop-up menu.)
•
Background: Sets the letterbox color. When you click the color well, the Colors window appears,
and you can choose a background color.