A Model for Very Wide Gamut HDR Displays that Accounts for the H-K Effect

We have developed a test method and computational model for predicting the brightness achieved by HDR (high dynamic range) televisions and computer monitors, in particular those with materials that feature primary colors having high spectral purity. The technological integration of quantum dot materials and emissive pixel lighting is expanding the color gamut level to attain a degree of performance unmatched in today's consumer and professional displays. These displays exhibit highly significant improvements in saturation and brightness due in part to the H-K (Helmholtz-Kohlrausch) effect, where people perceive some colors—notably reds and blues—as far brighter than its reference white. — We achieved a suitable methodology by blending the iCAM06 computational model² originally designed for HDR image evaluation with an improved treatment of vivid colors. Our data collection relied on a one-of-a-kind, yet commercially available 2D spectroradiometer that captures up to 1.4 million samples of spectral data samples across any image, an achievement impossible to attain manually. Our approach coupled nicely with the filter image-processing steps in iCAM06. Finally, we extracted image brightness for white, red and blue for determining the SEMI Perceptual Contrast Length³ (PCL) to assess the predicted improvement level of our model, then matched those results to subjective experiments. As a result, we have a methodology that can be used by display makers to measure and predict brightness as a function of color saturation in order to optimize luminance—notably for reducing power—in displays with spectrally pure primaries.

Published

2020-11

Content type

Original Research

Keywords

CIECAM02, HDR, High dynamic range, Helmholtz-Kohlrausch effect, iCAM06, Perceptual Contrast Length

DOI

10.5594/M001922