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<blockquote data-quote="Owlsroost" data-source="post: 1152371" data-attributes="member: 83973">They are special test patterns that are encoded with the full 0-255 possible range (to get BTB and WTW areas), but the 'legal' video content is between 16 and 235 - the BTB and WTW areas should be clipped so you can't see it on the display.Normal video files should not have any BTB or WTW content - it's effectively 'illegal', out-of-spec content.Anything below 16 and above 235 is not 'legal' video as per the digital video specifications.Because PCs have traditionally worked with displays using RGB in a 0-255 range (black to peak white), digital video content has to be expanded in this situation from 16-235 to 0-255, otherwise video black looks dark grey and video white looks pale grey on the display.All this 0-255 versus 16-235 situation is because of history - computer display standards and digital video standards evolved independently many years ago - they didn't 'converge' until years after the standards were established. (Working as a hardware designer, I've watched the situation develop over the last 35 years <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile&nbsp; &nbsp; :)" loading="lazy" data-shortname=":)" />)The reason video black and peak white levels are 16 and 235 is to allow for a small amount of BTB and WTW capture when filming if required - it's very difficult to keep exposure levels in a camera precise enough all the time to keep within 16-235. The BTB and WTW content is then removed when the video is edited, colour graded and encoded, but it's useful to have it at the editing stage.</blockquote>

[QUOTE="Owlsroost, post: 1152371, member: 83973"] They are special test patterns that are encoded with the full 0-255 possible range (to get BTB and WTW areas), but the 'legal' video content is between 16 and 235 - the BTB and WTW areas should be clipped so you can't see it on the display. Normal video files should not have any BTB or WTW content - it's effectively 'illegal', out-of-spec content. Anything below 16 and above 235 is not 'legal' video as per the digital video specifications. Because PCs have traditionally worked with displays using RGB in a 0-255 range (black to peak white), digital video content has to be expanded in this situation from 16-235 to 0-255, otherwise video black looks dark grey and video white looks pale grey on the display. All this 0-255 versus 16-235 situation is because of history - computer display standards and digital video standards evolved independently many years ago - they didn't 'converge' until years after the standards were established. (Working as a hardware designer, I've watched the situation develop over the last 35 years :)) The reason video black and peak white levels are 16 and 235 is to allow for a small amount of BTB and WTW capture when filming if required - it's very difficult to keep exposure levels in a camera precise enough all the time to keep within 16-235. The BTB and WTW content is then removed when the video is edited, colour graded and encoded, but it's useful to have it at the editing stage. [/QUOTE]

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