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TIFF Tag YCbCrCoefficients

IFDImage
Code529 (hex 0x0211)
NameYCbCrCoefficients
LibTiff nameTIFFTAG_YCBCRCOEFFICIENTS
TypeRATIONAL
Count3
Default299/1000, 587/1000 and 114/1000

Description

The transformation from RGB to YCbCr image data.

The transformation is specified as three rational values that represent the coefficients used to compute luminance, Y.

The three rational coefficient values, LumaRed, LumaGreen and LumaBlue, are the proportions of red, green, and blue respectively in luminance, Y.

Y, Cb, and Cr may be computed from RGB using the luminance coefficients specified by this field as follows:
Y = ( LumaRed * R + LumaGreen * G + LumaBlue * B )
Cb = ( B - Y ) / ( 2 - 2 * LumaBlue )
Cr = ( R - Y ) / ( 2 - 2 * LumaRed )

R, G, and B may be computed from YCbCr as follows:
R = Cr * ( 2 - 2 * LumaRed ) + Y
G = ( Y - LumaBlue * B - LumaRed * R ) / LumaGreen
B = Cb * ( 2 - 2 * LumaBlue ) + Y

The default values for this field are those defined by CCIR Recommendation 601- 1.

Related tags

YCbCrSubSampling
YCbCrPositioning

See also

TIFF Specification, revision 6.0, page 90