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Why is it that the deepness of blacks in video clips never match the other blacks on a monitor?

For example, opening a solid black PNG split-screened with a paused "fully black" video frame clearly shows the video to be a light gray in comparison.

Are there any technical reasons for this?

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2 Answers 2

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The way videos are encoded can change colors such as limiting the range of color it can express. Also it's likely that in the video itself it isn't "pure" black, meaning that even if I took a video in the middle of the night, there would be some light.

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Thanks, I'd not thought about the range compression. –  Rezzie Jun 4 '10 at 23:17
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There is something called setup or IRE for the black levels in video. On computers this ranges from 0 to 255, but in other video systems it may only range from 16 to 235. This is independent of video compression.

It's a complicated issue, but all you need to know is that sometimes the IRE is mismatched and what is black on one system (at level 16) is misinterpreted as dark gray on another.

http://www.glennchan.info/articles/technical/setup/75IREsetup.html

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Is there any way to adjust this in VLC? –  Rezzie Jun 4 '10 at 23:38
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