![]() Problem #2: The QuickTime player does not properly display decoded H.264 or MPEG-4 video: It lowers the contrast significantly, in order to convert from full range pixel values (0-255) to rec.601 pixel values. If you encode using QuickTime Pro instead of After Effects, you don’t get this gamma modification. I don’t know if Adobe products add the gamma boost when running on a Mac, or if Final Cut Pro adds a gamma adjustment. The situation for the QuickTime MPEG-4 codec is even worse: After Effects adds a gamma boost of 1/0.73, causing a maximum deviation of 30 pixel values for an input pixel value of 88.Īdobe Premier exhibits the same behavior when using the Adobe Media Encoder. If you want to “undo” this gamma modification, then you need to add a filter to your video timeline in AE: use the Gamma/Pedestal/Gain filter, and set a value of 0.88 for the red, green, and blue gamma. You can’t turn off this gamma adjustment by fiddling with the settings in the After Effects File > Project Settings Window, or by using color-managed content. AE does not apply this gamma boost when encoding using the QuickTime animation codec. In the AE preview window, the image that you see does not reflect the gamma modification. The green line is a reference that shows no change in pixel values (Y = X). The bottom row shows how the original pixels are changed after the AE gamma shift.The top row shows the original RGB gray scale pixel swatch values.The value swatches below the graph show how input values are changed: Here is the input/output transformation curve for RGB gray scale values: The maximum deviation occurs for an input value of 88, which is increased by 12 pixel values: ![]() Each output_pixel is equal to (input_pixel) ^ 0.88. Problem #1: If you use Adobe After Effects CS5 to encode QuickTime H.264 video on a PC, After Effects will first modify the pixel values to boost the mid-tone brightness, by applying a gamma of (1/0.88). There are actually two different problems, which tend to be conflated with each other: The problem is not always possible to fix, so it’s important to understand what’s going on. It’s commonly referred to as the “QuickTime gamma bug,” but it’s really a reduction in contrast, which converts the full range of pixel values (0-255) to the more limited pixel value range defined in in rec.601: rec.601 ![]() The QuickTime player causes H.264 and MPEG-4 encoded video to look washed-out. ![]()
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