Image Processing Reference
In-Depth Information
I've Mixed NTSC and PAL Footage and It Looks Jittery
Choose your target format and then use After Effects to change the time base for any video
that is not in the correct format. Then edit it together. Don't throw stuff at your compres-
sor that looks horrible to start with. Fix it up first if you can.
How Can I Save Lots of Bit Rate for Mobile Phone Output?
Apply some or all of these corrections:
Reduce the length.
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Re-render any edits to remove transition effects.
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Stabilize any moving video.
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Crop in to the action-safe or text-safe area.
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Reduce the frame rate.
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Choose still frames and make it into a slide show.
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Blur the detail in the chroma channel to reduce the high frequencies.
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Turn it into grayscale and discard the color.
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Mix down the audio from stereo to mono.
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Must I Scale the Video When I Move It from One Format to Another?
Not always. A 625-line video can scale down to 525 but a crop might work just as well.
A 525-line video might introduce artifacts when scaled up to 625 so adding a margin
around the edges and retaining the same-sized video could be a better solution. Run some
tests and preview the results.
Captions and Subtitles Look Horrible When Compressed
Crop them out and focus on the area of interest.
What Is the Best Interpolation Algorithm to Use?
Bi-cubic interpolation is better than bi-linear. Both are better than nearest neighbor.
Should I Sharpen the Image?
Sharpening should be avoided whenever possible. It is the opposite of de-noising and
introduces more grain noise. Over-sharpening makes the edges too harsh and leads to
overshoot artifacts.
Which Is Best, CBR or VBR?
Constant bit rate (CBR) is good when you know that your footage must fit within a bud-
geted bit rate. Variable bit rate (VBR) delivers better quality when the content is “bursty”
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