Convert CMYK data block to 4:2:2 YCCK MCU


FwStatus   fwiCMYKToYCCK422LS_MCU_8u16s_C4P4R ( const Fw8u * pSrcCMYKint srcStepFw16s * pDstMCU[4] );


pDstMCU[4]   Array of pointers to destination MCU image blocks.
pSrcCMYK   Pointer to source image ROI for CMYK image format.
srcStep   Source buffer step size (width of the buffer in bytes).


This function steps through a 16X8 data block in a source buffer, converts the source data from the CMYK color model to the YCCK color space with 4:2: chroma sub-sampling, level-shifts the unsigned values to signed values, creates a minimum coded unit, and writes the data to a destination buffer.

The following formulas are used to convert cyan, magenta, and yellow values to red, green, and blue values.

 R = 255 -C
 G = 255 -M
 B = 255 -Y

The following formulas are used to convert red, green, and blue values to luminance and chrominance values.

 Y = 0.299*R + 0.587*G + 0.114*B
 Cb = -0.16874*R - 0.33126*G + 0.5*B + 128
 Cr = 0.5*R - 0.41869*G - 0.08131*B + 128

The black (K) channel value remains the same during conversion.