colorsum

Colorsum is a term used in color science and digital imaging to denote a quantitative measure of the overall color content in a scene or image. It is obtained by combining color contributions from individual channels or spectral components, yielding a single value that represents total color energy or brightness in a region. In discrete-channel contexts such as RGB images, colorsum for a region is often computed as the sum of the red, green, and blue channel values across all pixels. This simple metric can be useful for comparing images or regions with varying illumination, though it can be biased by lighting conditions and clipping.

In spectral or perceptual contexts, colorsum refers to the additive combination of spectral power distributions from multiple light sources or reflectances, producing a resultant spectrum or a corresponding color percept using a chosen color-matching function. Colorsum is not a standardized color space or perceptual metric; it is a derived quantity that depends on device characteristics, gamma corrections, and dynamic range.

Applications of colorsum include image preprocessing and normalization to enable comparisons across images with different lighting, color balancing and exposure adjustment, and feature extraction for computer vision tasks that rely on aggregate color information. Because colorsum is sensitive to processing choices and device properties, it is often complemented by more robust analyses, such as color histograms in perceptually uniform spaces or color-difference measures.

See also additive color mixing, spectral power distribution, chromaticity, and histogram-based color analysis. Further reading in color science and image processing can provide foundational context for the aggregation and interpretation of color information.