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<div class="twikiMiddleContainer"><div class="twikiMain"><div class="twikiSearchResults"><div class="twikiSearchResultsHeader">&nbsp;<tt><b>&lt;&lt;O&gt;&gt;</b></tt>&nbsp; Difference Topic
		<b><a href="../../view/Cinelerra/VideoFormats">VideoFormats</a></b>
		(<a href="http://www.ftconsult.com/twiki/bin/view/Cinelerra/VideoFormats?rev=r1.1">r1.1</a> - 07&nbsp;Jan&nbsp;2004 - <a class="twikiLink" href="../../view/Main/AlexFerrer">AlexFerrer</a>)</div>
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<h2><a name="Video_Formats"> </a> Video Formats </h2>
<p />
<h3><a name="RGB_Formats"> </a> RGB Formats </h3>
The rgb formats are straightforward: 8 and 16 refers to the sample depth per
channel (per primary colour, that is).  rgb8 takes 24 bits per pixel; 8 for
red, 8 for green and 8 for blue.
Rgb16 takes 48 bits per pixel.  The "a" means "alpha", for transparency, and
adds another channel, with the same depth as the other three.  Alpha is required
for some layering and filtering techniques to work.
 Rgb is what computers use internally, as it is a straightforward representation
of the signals that are to be sent to the rgb monitor.
<p />
<h3><a name="YUV_Formats"> </a> YUV Formats </h3>
 Yuv is a quite different colour model, originating from colour television.
The Y component is pretty close to a plain black-and-white image, and is called
the "luminance".  The u and v components are the differences between the primary
colours; if there is no difference, the result is gray.  The u and v are called
the "chrominance".  In television, the Y component is the plain old black-and-white
signal, and u and v are squeezed into a gap in the old signal's transmission
spectrum.
 In digital video, the u and v components are more or less subsampled. I.e.
they are usually one half or one quarter the resolution of the luminance part.
Thus digital video get by with 9, 12 or 16 bits per pixel, instead of 24.  And
the human eye is rather forgiving; we can't distinguish small specks of colour,
unless their brightness differ.
<p />
<h4><a name="Other_Resources"> </a> Other Resources </h4>
There are several documents about colour models on the web.
<p />
<ul>
<li> <a href="http://www.cs.sfu.ca/CourseCentral/365/li/material/notes/Chap3/Chap3.4/Chap3.4.html" target="_top">http://www.cs.sfu.ca/CourseCentral/365/li/material/notes/Chap3/Chap3.4/Chap3.4.html</a>
</li>
<li> <a href="http://www.adamwilt.com/pix-sampling.html" target="_top">http://www.adamwilt.com/pix-sampling.html</a>
</li>
</ul>
<p />
-- <a class="twikiLink" href="../../view/Main/AlexFerrer">AlexFerrer</a> - 07 Jan 2004 <strong><em>from hroback @sourceforge.net heroines forum</em></strong>
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 <span class="twikiSeparator">|</span> <a href="VideoFormats">Diffs</a>  | <a href="http://www.ftconsult.com/twiki/bin/view/Cinelerra/VideoFormats?rev=1.1">r1.1</a>
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Revision r1.1 - 07 Jan 2004 - 20:00 - <a class="twikiLink" href="../../view/Main/AlexFerrer">AlexFerrer</a></span></div>
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