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Foil 7 JPEG Algorithm Specification -- I

From CPS600 Compression Presentation CPS600 Spring 1995 -- March 1995. by Roman Markowski and Geoffrey Fox * See also color IMAGE
First transfer the image into a suitable color space (RGB --> Image representations which separate luminance and chrominance YUV, YCbCr, etc.); the human eye is not as sensitive to high-frequency color as it is to high-frequency luminance
  • YUV is used in European TV standards and corresponds to YIQ in American NTSC. Y specifies gray-scale or luminance; U and V the chrominance
  • YCbCr is another color space where again Y is component of luminancy but Cb and Cr are respectively ther color components in blue(Cb) and red(Cr)
the luminance component is left at full resolution; color is usually reduced 2:1 (2v1h,2v2h)
  • This means chrominance reduced 2:1 vertically wiuth no horizontal reduction(2v1h) or reduced both horizontally and vertically (2v2h)

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