Off the Planckian Locus: Using 2D Chromaticity to Improve In-Camera Color

Fuente: arXiv
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Main Authors: Tedla, SaiKiran, Little, Joshua E., Karaimer, Hakki Can, Brown, Michael S.
Format: Preprint
Published: 2025
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author Tedla, SaiKiran
Little, Joshua E.
Karaimer, Hakki Can
Brown, Michael S.
author_facet Tedla, SaiKiran
Little, Joshua E.
Karaimer, Hakki Can
Brown, Michael S.
contents Traditional in-camera colorimetric mapping relies on correlated color temperature (CCT)-based interpolation between pre-calibrated transforms optimized for Planckian illuminants such as CIE A and D65. However, modern lighting technologies such as LEDs can deviate substantially from the Planckian locus, exposing the limitations of relying on conventional one-dimensional CCT for illumination characterization. This paper demonstrates that transitioning from 1D CCT (on the Planckian locus) to a 2D chromaticity space (off the Planckian locus) improves colorimetric accuracy across various mapping approaches. In addition, we replace conventional CCT interpolation with a lightweight multi-layer perceptron (MLP) that leverages 2D chromaticity features for robust colorimetric mapping under non-Planckian illuminants. A lightbox-based calibration procedure incorporating representative LED sources is used to train our MLP. Validated across diverse LED lighting, our method reduces angular reproduction error by 22% on average in LED-lit scenes, maintains backward compatibility with traditional illuminants, accommodates multi-illuminant scenes, and supports real-time in-camera deployment with negligible additional computational cost.
format Preprint
id arxiv_https___arxiv_org_abs_2511_17133
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Off the Planckian Locus: Using 2D Chromaticity to Improve In-Camera Color
Tedla, SaiKiran
Little, Joshua E.
Karaimer, Hakki Can
Brown, Michael S.
Computer Vision and Pattern Recognition
Traditional in-camera colorimetric mapping relies on correlated color temperature (CCT)-based interpolation between pre-calibrated transforms optimized for Planckian illuminants such as CIE A and D65. However, modern lighting technologies such as LEDs can deviate substantially from the Planckian locus, exposing the limitations of relying on conventional one-dimensional CCT for illumination characterization. This paper demonstrates that transitioning from 1D CCT (on the Planckian locus) to a 2D chromaticity space (off the Planckian locus) improves colorimetric accuracy across various mapping approaches. In addition, we replace conventional CCT interpolation with a lightweight multi-layer perceptron (MLP) that leverages 2D chromaticity features for robust colorimetric mapping under non-Planckian illuminants. A lightbox-based calibration procedure incorporating representative LED sources is used to train our MLP. Validated across diverse LED lighting, our method reduces angular reproduction error by 22% on average in LED-lit scenes, maintains backward compatibility with traditional illuminants, accommodates multi-illuminant scenes, and supports real-time in-camera deployment with negligible additional computational cost.
title Off the Planckian Locus: Using 2D Chromaticity to Improve In-Camera Color
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2511.17133