feat(analysis): split the density histogram into R, G, B and luminance - #914
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marcinz606 merged 13 commits intoAug 19, 2026
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The Analysis chart's density histogram only ever showed one merged luma trace, so a channel that clipped or sat far from the others (a strong color cast) was invisible until it showed up in the print. It now bins per channel on both engines, matching how the output histogram already works. The R/G/B/L split only earns its place where there is no print histogram doing that job already: Peek Negative. Everywhere else the density histogram stays a single merged luma trace, as before. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Summary
trace, so a channel that clipped or sat far from the others (a strong
color cast in the scan) was invisible until it showed up in the print.
density_histogram()) andGPU (
density_hist.wgsl) — matching the(4, N)[R, G, B, L] shape theoutput histogram already uses, with a CPU/GPU parity test alongside it.
Mon this fork afterfix(shortcuts): give Peek Flat Scan its own key, M, instead of | #912). Everywhere else the print's own output histogram already carries
color information, so the density histogram stays the single merged luma
trace it's always been — no visual change to the normal Analysis chart.
Each channel is scaled to its own peak, so a spike pinned to an edge bin
is that channel clipping, and a trace sitting apart from the others is a
color cast.
Test plan
make all(lint + type check + full test suite, 4234 passed)tests/test_exposure_analysis.py(per-channelbinning + GPU/CPU parity),
tests/test_readout_and_curve_feedback.py(channel/luma-only paint toggle),
tests/test_density_histogram_channel_wiring.py(Peek Negative wiring)
still shows the single merged trace, toggled Peek Negative and
confirmed the R/G/B/L split renders with visibly distinct peaks
🤖 Generated with Claude Code