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603 lines
18 KiB
HTML
603 lines
18 KiB
HTML
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<HTML>
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<HEAD><TITLE>xiph.org: Ogg Theora documentation</TITLE></HEAD>
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<BODY BGCOLOR="#FFFFFF" TEXT="#202020" LINK="#006666" VLINK="#000000">
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<H1><FONT COLOR="#000070">
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Ogg Theora I specification: color space conventions
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</FONT></H1>
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<H1>Overview</H1>
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<P>
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There are a large number of different color standards used in digital video.
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Since Theora is a lossy codec, it restricts itself to only a few of them to
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simplify playback.
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Unlike the alternate method of describing all the parameters of the color
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model, this allows a few dedicated routines for color conversion to be written
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and heavily optimized in a decoder.
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More flexible conversion functions should instead be specified in an encoder,
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where additional computational complexity is more easily tolerated.
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The color spaces were selected to give a fair representation of color standards
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in use around the world today.
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Most of the standards that do not exactly match one of these can be converted
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to one fairly easily.
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</P>
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<P>
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The Theora codec identification header contains an 8-bit value that describes
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the color space.
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This merely selects one of the color spaces available from an enumerated list.
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Currently, only two color spaces are defined, with a third possibility that
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indicates the color space is "unknown".
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All of them are Y'C<SUB>b</SUB>C<SUB>r</SUB> color spaces with one luma channel
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and two chroma channels.
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Each channel contains 8-bit discrete values in the range 0-255, which represent
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non-linear gamma pre-corrected signals.
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</P>
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<H2>color space parameters</H2>
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<P>
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The parameters which describe each color space are listed below.
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These are the parameters needed to map colors from the encoded
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Y'C<SUB>b</SUB>C<SUB>r</SUB> representation to the device-independent color
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space CIE XYZ (1931).
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</P>
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<DL>
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<DT>Y'C<SUB>b</SUB>C<SUB>r</SUB> to Y'P<SUB>b</SUB>P<SUB>r</SUB></DT>
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<DD>
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<P>
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This conversion takes 8-bit discrete values in the range 0-255 and maps them to
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real values in the range [0,1] for Y and [-1/2,1/2] for P<SUB>b</SUB>
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and P<SUB>r</SUB>.
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Because some values may fall outside the offset and excursion defined for each
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channel in the Y'C<SUB>b</SUB>C<SUB>r</SUB> space, the results may fall
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outside these ranges in Y'P<SUB>b</SUB>P<SUB>r</SUB> space.
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No clamping should be done at this stage.
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</P>
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<P>
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Parameters: <EM>Offset<SUB>Y,C<SUB>b</SUB>,C<SUB>r</SUB></SUB></EM>,
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<EM>Excursion<SUB>Y,C<SUB>b</SUB>,C<SUB>r</SUB>,</SUB></EM>
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</P>
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<TABLE>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">Y'<SUB>out</SUB></TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">
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(Y'<SUB>in</SUB>-<EM>Offset<SUB>Y</SUB></EM>)/
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<EM>Excursion<SUB>Y</SUB></EM>
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</TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">P<SUB>b</SUB></TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">
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(C<SUB>b</SUB>-<EM>Offset<SUB>C<SUB>b</SUB></SUB></EM>)/
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<EM>Excursion<SUB>C<SUB>b</SUB></SUB></EM>
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</TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">P<SUB>r</SUB></TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">
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(C<SUB>r</SUB>-<EM>Offset<SUB>C<SUB>r</SUB></SUB></EM>)/
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<EM>Excursion<SUB>C<SUB>r</SUB></SUB></EM>
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</TD>
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</TR>
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</TABLE>
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</DD>
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<DT>Y'P<SUB>b</SUB>P<SUB>r</SUB> to R'G'B'</DT>
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<DD>
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<P>
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This conversion takes the one luma and two chroma channel representation and
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maps it to the non-linear R'G'B' space used to drive actual output devices.
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Values should be clamped into the range [0,1] after this stage.
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<P>
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Parameters: <EM>K<SUB>b</SUB></EM>, <EM>K<SUB>r</SUB></EM>
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</P>
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<TABLE>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">R'</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">Y' + 2(1-<EM>K<SUB>r</SUB></EM>)P<SUB>r</SUB></TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">G'</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">
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Y' +
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2((<EM>K<SUB>b</SUB></EM>-1)<EM>K<SUB>b</SUB></EM>/
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(1-<EM>K<SUB>b</SUB></EM>-<EM>K<SUB>r</SUB></EM>))P<SUB>b</SUB> +
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2((<EM>K<SUB>r</SUB></EM>-1)<EM>K<SUB>r</SUB></EM>/
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(1-<EM>K<SUB>b</SUB></EM>-<EM>K<SUB>r</SUB></EM>))P<SUB>r</SUB>
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</TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">B'</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">Y' + 2(1-<EM>K<SUB>b</SUB></EM>)P<SUB>b</SUB></TD>
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</TR>
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</TABLE>
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</DD>
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<DT>R'G'B' to RGB (Output device gamma correction)</DT>
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<DD>
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<P>
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This conversion takes the non-linear R'G'B' voltage levels and maps it to the
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linear light levels produced by the actual output device.
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Note that this conversion is only that of the output device, and its inverse is
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<EM>not</EM> that used by the input device.
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Because a dim viewing environment is assumed in most television standards, the
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overall gamma between the input and output devices is usually around 1.1 to
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1.2, and not a strict 1.0.
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</P>
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<P>
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For calibration with actual output devices, the model
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<TABLE>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">L</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">(E'+Δ)<SUP><EM>γ</EM></SUP></TD>
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</TR>
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</TABLE>
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should be used, with Δ the free parameter and <EM>γ</EM> held
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fixed to the value specified in this document.
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The conversion function presented here is an idealized version with Δ=0.
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</P>
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<P>
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Parameters: <EM>γ</EM>
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</P>
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<TABLE>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">R</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">R'<SUP><EM>γ</EM></SUP></TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">G</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">G'<SUP><EM>γ</EM></SUP></TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">B</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">B'<SUP><EM>γ</EM></SUP></TD>
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</TR>
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</TABLE>
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</DD>
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<DT>RGB to R'G'B' (Input device gamma correction)</DT>
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<DD>
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<P>
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This conversion takes linear light levels and maps them to the non-linear
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voltage levels used to drive the actual output device.
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This information is merely informative.
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It is not required for building a decoder or for converting between the various
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formats and the actual output capabilities of a particular device.
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</P>
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<P>
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A linear segment is introduced on the low end to reduce noise in dark areas of
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the image.
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The rest of the scale is adjusted so that the power segment of the curve
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intersects the linear segment with the proper slope, and so that it still maps
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0 to 0 and 1 to 1.
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</P>
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<P>
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Parameters: <EM>β</EM>, <EM>α</EM>, <EM>δ</EM>,
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<EM>ε</EM>
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</P>
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<TABLE>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">R'</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">
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(1+<EM>ε</EM>)R<SUP>β</SUP>-<EM>ε</EM>
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</TD>
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<TD>for <EM>δ</EM> ≤ R ≤ 1</TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">R'</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT"><EM>α</EM>R</TD>
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<TD>for 0 ≤ R < <EM>δ</EM></TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">G'</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">
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(1+<EM>ε</EM>)G<SUP>β</SUP>-<EM>ε</EM>
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</TD>
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<TD>for <EM>δ</EM> ≤ G ≤ 1</TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">G'</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT"><EM>α</EM>G</TD>
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<TD>for 0 ≤ G < <EM>δ</EM></TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">B'</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT">
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(1+<EM>ε</EM>)B<SUP>β</SUP>-<EM>ε</EM>
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</TD>
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<TD>for <EM>δ</EM> ≤ B ≤ 1</TD>
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</TR>
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<TR VALIGN="BOTTOM">
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<TD ALIGN="RIGHT">B'</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT"><EM>α</EM>B</TD>
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<TD>for 0 ≤ B < <EM>δ</EM></TD>
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</TR>
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</TABLE>
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</DD>
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<DT>RGB to CIE XYZ (1931)</DT>
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<DD>
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<P>
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This conversion maps a device-dependent linear RGB space to the
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device-independent linear CIE XYZ space.
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The parameters are the CIE chromaticity coordinates of the three primaries,
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red, green, and blue, as well as the chromaticity coordinates of the white
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point of the device.
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This is how hardware manufacturers and standards typically describe a
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particular RGB space.
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The math required to convert these parameters into a useful transformation
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matrix is reproduced below.
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</P>
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<P>
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Parameters: <EM>x<SUB>r,g,b,w</SUB></EM>, <EM>y<SUB>r,g,b,w</SUB></EM>
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</P>
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<TABLE>
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<TR>
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<TD ALIGN="RIGHT">F</TD>
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<TD>=</TD>
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<TD ALIGN="LEFT"><TABLE><TR>
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<TD><FONT SIZE="300%">(</FONT></TD>
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<TD><TABLE>
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<TR>
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<TD ALIGN="CENTER"><EM>x<SUB>r</SUB></EM>/<EM>y<SUB>r</SUB></EM></TD>
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<TD ALIGN="CENTER"><EM>x<SUB>g</SUB></EM>/<EM>y<SUB>g</SUB></EM></TD>
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<TD ALIGN="CENTER"><EM>x<SUB>b</SUB></EM>/<EM>y<SUB>b</SUB></EM></TD>
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</TR>
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<TR>
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<TD ALIGN="CENTER">1</TD>
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<TD ALIGN="CENTER">1</TD>
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<TD ALIGN="CENTER">1</TD>
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</TR>
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<TR>
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<TD ALIGN="CENTER">
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(1-<EM>x<SUB>r</SUB></EM>-<EM>y<SUB>r</SUB></EM>)/<EM>y<SUB>r</SUB></EM>
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</TD>
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<TD ALIGN="CENTER">
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(1-<EM>x<SUB>g</SUB></EM>-<EM>y<SUB>g</SUB></EM>)/<EM>y<SUB>g</SUB></EM>
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</TD>
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<TD ALIGN="CENTER">
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(1-<EM>x<SUB>b</SUB></EM>-<EM>y<SUB>b</SUB></EM>)/<EM>y<SUB>b</SUB></EM>
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</TD>
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</TR>
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</TABLE></TD>
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<TD<FONT SIZE="300%">)</FONT></TD>
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</TR></TABLE></TD>
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</TR>
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<TR>
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<TD ALIGN="RIGHT"><TABLE><TR>
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<TD><FONT SIZE="300%">(</FONT></TD>
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<TD><TABLE>
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<TR><TD ALIGN="CENTER">s<SUB>r</SUB></TD></TR>
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<TR><TD ALIGN="CENTER">s<SUB>g</SUB></TD></TR>
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<TR><TD ALIGN="CENTER">s<SUB>b</SUB></TD></TR>
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</TABLE></TD>
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<TD><FONT SIZE="300%">)</FONT></TD>
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</TR></TABLE></TD>
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<TD>=</TD>
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<TD ALIGN="LEFT"><TABLE><TR>
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<TD>F<SUP>-1</SUP><FONT SIZE="300%">(</FONT></TD>
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<TD><TABLE>
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<TR><TD ALIGN="CENTER"><EM>x<SUB>w</SUB></EM>/<EM>y<SUB>w</SUB></EM></TD></TR>
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<TR><TD ALIGN="CENTER">1</TD></TR>
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<TR><TD ALIGN="CENTER">
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(1-<EM>x<SUB>w</SUB></EM>-<EM>y<SUB>w</SUB></EM>)/<EM>y<SUB>w</SUB></EM>
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</TD></TR>
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</TABLE></TD>
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<TD><FONT SIZE="300%">)</FONT></TD>
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</TR></TABLE></TD>
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</TR>
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<TR>
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<TD ALIGN="RIGHT"><TABLE><TR>
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<TD><FONT SIZE="300%">(</FONT></TD>
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<TD><TABLE>
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<TR><TD ALIGN="CENTER">X</TD></TR>
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<TR><TD ALIGN="CENTER">Y</TD></TR>
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<TR><TD ALIGN="CENTER">Z</TD></TR>
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</TABLE></TD>
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<TD><FONT SIZE="300%">)</FONT></TD>
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</TR></TABLE></TD>
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<TD>=</TD>
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<TD ALIGN="LEFT"><TABLE><TR>
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<TD>F<FONT SIZE="300%">(</FONT></TD>
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<TD><TABLE>
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<TR><TD ALIGN="CENTER">s<SUB>r</SUB>R</TD></TR>
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<TR><TD ALIGN="CENTER">s<SUB>g</SUB>G</TD></TR>
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<TR><TD ALIGN="CENTER">s<SUB>b</SUB>B</TD></TR>
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</TABLE></TD>
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<TD><FONT SIZE="300%">)</FONT></TD>
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</TR></TABLE></TD>
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</TR>
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</TABLE>
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</DD>
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</DL>
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<H2>available color spaces</H2>
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<P>
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||
|
|
These are the color spaces currently defined for use by Ogg Theora video.
|
||
|
|
Each one has a short name, with which it is referred to in this document, and
|
||
|
|
a more detailed specification of the standards from which its parameters are
|
||
|
|
derived.
|
||
|
|
Some standards do not specify all the parameters necessary.
|
||
|
|
For these unspecified parameters, this document serves as the definition of
|
||
|
|
what should be used when encoding or decoding Ogg Theora video.
|
||
|
|
<H3>Rec 470M (Rec. ITU-R BT.470-6 System M/NTSC with Rec. ITU-R BT.601-5)</H3>
|
||
|
|
<P>
|
||
|
|
This color space is used by broadcast television and DVDs in much of the
|
||
|
|
Americas, Japan, Korea, and the Union of Myanmar
|
||
|
|
[<A HREF="#Rec470">Rec470</A>].
|
||
|
|
This color space may also be used for System M/PAL (Brazil), with an
|
||
|
|
appropriate conversion supplied by the encoder to compensate for the
|
||
|
|
different gamma value.
|
||
|
|
See the Rec 470BG section for an appropriate gamma value to assume for M/PAL
|
||
|
|
input.
|
||
|
|
</P>
|
||
|
|
<P>
|
||
|
|
In the US, studio monitors are adjusted to a D65 white point
|
||
|
|
(<EM>x<SUB>w</SUB></EM>,<EM>y<SUB>w</SUB></EM>=0.313,0.329).
|
||
|
|
In Japan, studio monitors are adjusted to a D white of 9300K
|
||
|
|
(<EM>x<SUB>w</SUB></EM>,<EM>y<SUB>w</SUB></EM>=0.285,0.293).
|
||
|
|
</P>
|
||
|
|
<P>
|
||
|
|
Rec 470 does not specify a digital encoding of the color signals.
|
||
|
|
For Ogg Theora, Rec. ITU-R BT.601-5 is used, starting from the R'G'B' signals
|
||
|
|
specified by Rec 470 [<A HREF="#Rec601">Rec601</A>].
|
||
|
|
</P>
|
||
|
|
<P>
|
||
|
|
<P>
|
||
|
|
Rec 470 does not specify an input gamma function.
|
||
|
|
For Ogg Theora, the Rec 709 input function is used.
|
||
|
|
This is the same as that specified by SMPTE 170M, which claims to reflect
|
||
|
|
modern practice in the creation of NTSC signals (c. 1994)
|
||
|
|
[<A HREF="#SMPTE170M">SMPTE170M</A>].
|
||
|
|
</P>
|
||
|
|
<H4>parameters</H4>
|
||
|
|
<TABLE>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>Offset<SUB>Y,C<SUB>b</SUB>,C<SUB>r</SUB></SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT" COLSPAN="2">(16,128,128)</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT">
|
||
|
|
<EM>Excursion<SUB>Y,C<SUB>b</SUB>,C<SUB>r</SUB></SUB></EM>
|
||
|
|
</TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT" COLSPAN="2">(219,224,224)</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>K<SUB>b</SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT" COLSPAN="2">0.114</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>K<SUB>r</SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT" COLSPAN="2">0.299</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>γ</EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT">2.2</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>β</EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT">0.45</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>α</EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT">4.5</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>δ</EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT">0.018</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>ε</EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT">0.099</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>x<SUB>r</SUB></EM>,<EM>y<SUB>r</SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD>0.67,</TD>
|
||
|
|
<TD>0.33</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>x<SUB>g</SUB></EM>,<EM>y<SUB>g</SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD>0.21,</TD>
|
||
|
|
<TD>0.71</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>x<SUB>b</SUB></EM>,<EM>y<SUB>b</SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD>0.14,</TD>
|
||
|
|
<TD>0.08</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT">
|
||
|
|
(Illuminant C) <EM>x<SUB>w</SUB></EM>,<EM>y<SUB>w</SUB></EM>
|
||
|
|
</TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD>0.310,</TD>
|
||
|
|
<TD>0.316</TD>
|
||
|
|
</TR>
|
||
|
|
</TABLE>
|
||
|
|
<H3>
|
||
|
|
Rec 470BG (Rec. ITU-R BT.470-6 Systems B and G with Rec. ITU-R BT.601-5)
|
||
|
|
</H3>
|
||
|
|
<P>
|
||
|
|
This color space is used by the PAL and SECAM systems in much of the rest of
|
||
|
|
the world [<A HREF="#Rec470">Rec470</A>].
|
||
|
|
This can be used directly by systems (B, B1, D, D1, G, H, I, K, N)/PAL and (B,
|
||
|
|
D, G, H, K, K1, L)/SECAM.
|
||
|
|
</P>
|
||
|
|
<P>
|
||
|
|
Note that the Rec 470BG chromaticity values are different from those specified
|
||
|
|
in Rec 470M.
|
||
|
|
When PAL and SECAM systems were first designed, they were based upon the same
|
||
|
|
primaries as NTSC.
|
||
|
|
However, as methods of making color picture tubes have changed, the primaries
|
||
|
|
used have changed as well.
|
||
|
|
The US recommends using correction circuitry to approximate the existing,
|
||
|
|
standard NTSC primaries.
|
||
|
|
Current PAL and SECAM systems have standardized on primaries in accord with
|
||
|
|
more recent technology.
|
||
|
|
</P>
|
||
|
|
<P>
|
||
|
|
Rec 470 provisionally permits the use of the NTSC chromaticity values (given
|
||
|
|
above) with legacy PAL and SECAM equipment.
|
||
|
|
In Ogg Theora, material must be decoded assuming the new PAL and SECAM
|
||
|
|
primaries.
|
||
|
|
Material intended for display on old legacy devices should be converted by the
|
||
|
|
decoder.
|
||
|
|
</P>
|
||
|
|
<P>
|
||
|
|
The official Rec 470BG specifies a gamma value of <EM>γ</EM>=2.8.
|
||
|
|
However, in practice this value is unrealistically high
|
||
|
|
[<A HREF="#RefPoy97">Poy97</A>].
|
||
|
|
Rec 470BG states that the overall system gamma should be approximately
|
||
|
|
<EM>γ</EM>/<EM>β</EM>=1.2.
|
||
|
|
However, most cameras pre-correct with a gamma value of <EM>β</EM>=0.45,
|
||
|
|
which suggests an output device gamma of approximately <EM>γ</EM>=2.67.
|
||
|
|
This is the value recommended for use with PAL systems in Ogg Theora.
|
||
|
|
</P>
|
||
|
|
<P>
|
||
|
|
Rec 470 does not specify a digital encoding of the color signals.
|
||
|
|
For Ogg Theora, Rec. ITU-R BT.601-5 is used, starting from the R'G'B' signals
|
||
|
|
specified by Rec 470 [<A HREF="#Rec601">Rec601</A>].
|
||
|
|
</P>
|
||
|
|
<P>
|
||
|
|
Rec 470 does not specify an input gamma function.
|
||
|
|
For Ogg Theora, the Rec 709 input function is used.
|
||
|
|
</P>
|
||
|
|
<H4>parameters</H4>
|
||
|
|
<TABLE>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>Offset<SUB>Y,C<SUB>b</SUB>,C<SUB>r</SUB></SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT" COLSPAN="2">(16,128,128)</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT">
|
||
|
|
<EM>Excursion<SUB>Y,C<SUB>b</SUB>,C<SUB>r</SUB></SUB></EM>
|
||
|
|
</TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT" COLSPAN="2">(219,224,224)</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>K<SUB>b</SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT" COLSPAN="2">0.114</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>K<SUB>r</SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT" COLSPAN="2">0.299</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>γ</EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT">2.67</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>β</EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT">0.45</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>α</EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT">4.5</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>δ</EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT">0.018</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>ε</EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD ALIGN="LEFT">0.099</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>x<SUB>r</SUB></EM>,<EM>y<SUB>r</SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD>0.64,</TD>
|
||
|
|
<TD>0.33</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>x<SUB>g</SUB></EM>,<EM>y<SUB>g</SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD>0.29,</TD>
|
||
|
|
<TD>0.60</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT"><EM>x<SUB>b</SUB></EM>,<EM>y<SUB>b</SUB></EM></TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD>0.15,</TD>
|
||
|
|
<TD>0.06</TD>
|
||
|
|
</TR>
|
||
|
|
<TR VALIGN="BOTTOM">
|
||
|
|
<TD ALIGN="RIGHT">
|
||
|
|
(D65) <EM>x<SUB>w</SUB></EM>,<EM>y<SUB>w</SUB></EM>
|
||
|
|
</TD>
|
||
|
|
<TD>=</TD>
|
||
|
|
<TD>0.313,</TD>
|
||
|
|
<TD>0.329</TD>
|
||
|
|
</TR>
|
||
|
|
</TABLE>
|
||
|
|
<H2>references</H2>
|
||
|
|
<DL>
|
||
|
|
<DT>[<A NAME="Poy97">Poy97</A>]</DT>
|
||
|
|
<DD>
|
||
|
|
Poynton, Charles, <I>Frequently-Asked Questions about Gamma</I>.
|
||
|
|
<A HREF="http://www.poynton.com/GammaFAQ.html">http://www.poynton.com/GammaFAQ/html</A>,
|
||
|
|
Feb. 1997.
|
||
|
|
</DD>
|
||
|
|
<DT>[<A NAME="Rec470">Rec470</A>]</DT>
|
||
|
|
<DD>
|
||
|
|
Recommendation ITU-R BT.470-6, <I>Conventional Television Systems</I>
|
||
|
|
(1970, revised 1998). International Telecommunications Union, 1211 Geneva 20,
|
||
|
|
Switzerland.
|
||
|
|
</DD>
|
||
|
|
<DT>[<A NAME="Rec601">Rec601</A>]</DT>
|
||
|
|
<DD>
|
||
|
|
Recommendation ITU-R BT.601-5, <I>Studio Encoding Parameters of
|
||
|
|
Digital Television for Standard 4:3 and Wide-Screen 16:9 Aspect Ratios</I>
|
||
|
|
(1982, revised 1995). International Telecommunications Union, 1211 Geneva 20,
|
||
|
|
Switzerland.
|
||
|
|
</DD>
|
||
|
|
<DT>[<A NAME="Rec709">Rec709</A>]</DT>
|
||
|
|
<DD>
|
||
|
|
Recommendation ITU-R BT.709-5, <I>Parameter values for the
|
||
|
|
HDTV standards for production and international programme exchange</I>
|
||
|
|
(1990, revised 2002). International Telecommunications Union, 1211 Geneva 20,
|
||
|
|
Switzerland.
|
||
|
|
</DD>
|
||
|
|
<DT>[<A NAME="SMPTE170M">SMPTE170M</A>]</DT>
|
||
|
|
<DD>
|
||
|
|
Society of Motion Picture and Television Engineers, <I>Television —
|
||
|
|
Composite Analog Video Signal — NTSC for Studio Applications</I>.
|
||
|
|
SMPTE-170M, 1994
|
||
|
|
</DD>
|
||
|
|
<DT>[<A NAME="SMPTE240M">SMPTE240M</A>]</DT>
|
||
|
|
<DD>
|
||
|
|
Society of Motion Picture and Television Engineers, <I>Television —
|
||
|
|
Signal Parameters — 1125-Line High-Definition Production</I>.
|
||
|
|
SMPTE-240M, 1999.
|
||
|
|
</DD>
|
||
|
|
</DL>
|
||
|
|
</BODY>
|
||
|
|
</HTML>
|