Six different methods for white-balancing digital images were compared in terms of their ability to produce white-balanced
colors close to those viewed under a specific viewing illuminant. The six methods were: native camera RGB, XYZ, CAM02,
ITU Rec BT.709 RGB, sharpened camera RGB, and illuminant-dependent. 4096 different sets of camera sensitivities were
synthesized; 170 objects were evaluated under a canonical viewing illuminant (D65) and six additional taking illuminants (A,
D50, D75, F2, F7, and F11). Each white balancing method was exercised in turn, and the mean and 90th percentile ΔE*<sub>ab</sub>
We found that illuminant-dependent characterization produced the best results, sharpened camera RGB and native camera
RGB were next best, XYZ and CAM02 were often not far behind, and balancing in the -709 primaries was significantly worse.
We recommend that, whenever the illuminant is identified, the illuminant-dependent technique be employed because of its
A metric for comparison of radiance (e.g., reflectance) spectra, based on colorimetric principles, is described. In essence, the metric is a linear approximation to the sum of a series of ΔE*<sub>ab</sub> values wherein the two spectra differ only within a single narrow wavelength band. This metric has previously been suggested as a measure of lack-of-fit between a spectral-based color model and experimental observations, as well as an optimization criterion in modeling the color behavior of color output devices.
In this paper, the application of the metric as an index of metamerism is presented. Unlike the current CIE-recommended special metameric indices, the new proposal does not require the specification of a single set of trial conditions. Further, unlike previous spectrum-based proposals, it provides results in familiar units of ΔE*<sub>ab</sub>.