gamut_mapping: greatly simplify perceptual tone mapping

Instead of applying this complicated soft-knee along the gamma axis, as inspired by the gamut mapping paper this method was originally based on, I found that simply scaling the chromaticity axis by the equivalent knee function works extremely well, together with hard-clipping for out-of-gamut parts of the image.

(Maybe we need to re-introduce some soft clipping to the source gamut)

added 2 commits

• 0a7c4533 - Revert "gamut_mapping: clip to source gamut in perceptual mode"
• d8b8f7b0 - gamut_mapping: greatly simplify perceptual tone mapping

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changed milestone to %v6.283+

added 2 commits

• 0c789e04 - gamut_mapping: add chromaticity margin to perceptual mode
• 42fc67bb - gamut_mapping: add extra intensity-dependent source margin

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added 2 commits

• 89a4dff2 - gamut_mapping: factor out softclip function
• a4fd0060 - gamut_mapping: soft-clip in RGB after mapping

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added 2 commits

• 40355d99 - gamut_mapping: factor out softclip function
• dff7246e - gamut_mapping: soft-clip in RGB after mapping

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approved this merge request

added 6 commits

• 363cada9 - 1 commit from branch videolan:master
• ab68ef88 - Revert "gamut_mapping: clip to source gamut in perceptual mode"
• 599ea166 - gamut_mapping: greatly simplify perceptual tone mapping
• a4ae197a - gamut_mapping: add chromaticity margin to perceptual mode
• 3042c927 - gamut_mapping: factor out softclip function
• 17aecaf7 - gamut_mapping: soft-clip in RGB after mapping

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merged