ham_convert 1.10.0

New in this version: ability to use the ICtCp colorspace for HAM error calculation, option to exclude the first palette color from DynamicHires conversion, larger program window and fonts, code cleanup.

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  • HAM6/HAM8: option to calculate HAM error and color distance in the ICtCp colorspace instead of LAB. ICtCp is newer (2019) than previous LAB-based color distance functions, often produce higher quality output without CIE94 red-orange glitches and is more workable than CIEDE2000. Weights for each component can be adjusted in the extra options tab. ICtCp can be also enabled in cli mode with “color_ictcp” parameter.
    First experiments with CIE94 and CIEDE2000 started in 2015 and soon some issues were discovered that were always a problem despite superior image quality compared to conventional RGB-based color difference metrics. CIEDE2000 proved quite unsuitable for HAM and CIE94 sometimes produced glitches in red areas with undesired patches of orange or even grayscale depending on the palette. They were mostly eliminated in 1.6.0 by additional glitch detection and re-calculation using CIE76. There was ongoing search for more permanent solution. Colorspaces other than CIELAB and their newer successors were evaluated and recently ICtCp was found to produce images of similar quality to CIE94, but without its glitches.
  • Dynamic Hires: option to exclude first palette color (resulting image will never use the first palette color).
  • Disabled setting alpha flag when saving to a PCHGF_32BIT format in DymamicHires AGA and Atari 8-bit.
  • Larger program window, fonts, various ui tweaks.
  • Code cleanup.

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