13 September 2008 CIELAB to CMYK color conversion in the transform domain for JPEG compressed images
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A new technique is described for color conversions of JPEG images. For each input block of each component, the conversion for the 63 AC coefficients is processed in the transform domain instead of the spatial domain. Only the DC coefficients for each input block of the color components are transformed to the spatial domain and then processed through the traditional lookup table to create color-converted output DC coefficients for each block. Given each converted DC value for each block, the remaining 63 AC coefficients are then converted directly in the transform domain via scaling functions that are accessed via a table as a function of only the DC term. For n-dimensional color space to m-dimensional color space conversion, n component blocks create m component blocks. An IDCT can then be applied to the m component blocks to create spatial domain data or these output blocks can be quantized and entropy encoded to create JPEG compressed data in the m-dimensional color space.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Yue Qiao, Joan L. Mitchell, Nenad Rijavec, Arianne T. Hinds, "CIELAB to CMYK color conversion in the transform domain for JPEG compressed images", Proc. SPIE 7073, Applications of Digital Image Processing XXXI, 707306 (13 September 2008); doi: 10.1117/12.796915; https://doi.org/10.1117/12.796915

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