Add CCT ramp mode for D4K-3ch with colorimetric accuracy#147
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GlassOnTin wants to merge 2 commits intoToyKeeper:trunkfrom
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Add CCT ramp mode for D4K-3ch with colorimetric accuracy#147GlassOnTin wants to merge 2 commits intoToyKeeper:trunkfrom
GlassOnTin wants to merge 2 commits intoToyKeeper:trunkfrom
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Adds tooling and documentation for achieving accurate color reproduction on multi-channel LED flashlights like the D4K-3ch. tools/led_colorimetry.py: - Compute optimal RGB mixing coefficients from LED spectral data - Calculate Planckian locus (blackbody) color coordinates - Generate lookup tables for CCT-to-RGB conversion - Support for arbitrary LED combinations and color temperatures docs/color-science.md: - Color science fundamentals (CIE 1931, chromaticity) - LED spectral characteristics and mixing theory - Derivation of PWM scaling factors for balanced color - Planckian locus mathematics for CCT mode - Visual diagrams: chromaticity, LED SPDs, color mixing tools/generate_color_figures.py: - Generates all documentation figures from source data - Chromaticity diagrams, spectral plots, mixing visualizations
Adds a correlated color temperature (CCT) mode that smoothly transitions along the Planckian locus (blackbody curve) from warm to cool white. New channel mode CM_CCT: - Default range: 2700K (warm incandescent) to 6500K (D65 daylight) - Extended range option: 1800K to 10000K (define CCT_TABLE_EXTENDED) - 3H gesture adjusts color temperature - Lookup table interpolation for smooth transitions Implementation: - 16-entry RGB lookup table computed from CIE 1931 colorimetry - Values pre-scaled for RGBG LED configuration (dual green LEDs) - Bilinear interpolation between table entries - Gradual tick support for smooth ramping The LUT was generated using tools/led_colorimetry.py which computes optimal RGB values to match points along the Planckian locus, accounting for the specific LED spectral characteristics of the D4K-3ch. Also enables all 9 channel modes by default: - CM_MAIN2, CM_LED3, CM_LED4, CM_ALL (single/combined channels) - CM_BLEND34A, CM_BLEND34B (manual R+B, R+G blends) - CM_HSV (hue wheel), CM_AUTO3 (cyan auto-blend), CM_CCT (new)
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Video with the camera white balance locked at 6500K. Then varying the torch colour temperature: VID_20251212_152253_431.mp4 |
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VID_20251212_152834_152.mp4 |
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Summary
Adds a correlated color temperature (CCT) channel mode for the Emisar D4K-3ch that produces accurate white tones along the Planckian locus (blackbody curve).
Channel Modes
The D4K-3ch now has 9 channel modes enabled by default:
Implementation Details
CCT_TABLE_EXTENDEDdefineTooling
tools/led_colorimetry.pycomputes optimal RGB values from:Test Plan