Rodney L. Heckaman

Evaluation of HDR tone‐mapping algorithms using a high‐dynamic‐range display to emulate real scenes

— Current HDR display technology approaches the dynamic-range capabilities of the fully adapted human visual system. As such, this technology has potential for performing as a surrogate for real-world scenes in the perceptual evaluation of high-dynamic-range (HDR) image-reproduction algorithms that aim to map HDR scenes to the limited dynamic ranges available in typical display and print technology. Compared with direct image assessment in comparison with real-world scenes, it is clear that use of HDR display technology has the benefit of simplicity in experimental design while maintaining the HDR of the original scene. To evaluate this potential application of HDR display technology, seven published versions of well-known HDR tone-mapping algorithms were benchmarked for perceptual rendering accuracy against each of four real-world scenes constructed in the laboratory and against corresponding images on an HDR display. The results illustrate that visual assessments obtained from the HDR display and those obtained from real-world scenes are in good agreement, validating the potential for HDR display technology as an evaluation tool in this context.

Effect of DLP projector white channel on perceptual gamut

— The effect of white-channel enhancement as implemented in the Texas Instrument DLP™ digital projector technology is evaluated theoretically using both the CIELAB and the CIECAM02 color appearance models and experimentally through psychophysical testing using real images. Both theory and test results confirm a compression of perceptual gamut in both chroma and colorfulness as a result of the added white channel. Hence, while this technology is ideal for viewing graphics and text under ambient conference-room conditions where lightness contrast is important, it is necessarily less than ideal for viewing images or in home-theater environments where color is important.

18.3: Rendering Digital Cinema and Broadcast TV Content to Wide Gamut Display Media

Much more is possible in achieving brighter, more vibrant colors for a richer visual experience in emerging, wide-gamut display media. Yet, both digital cinema and broadcast TV content fall well short of this promise. In this paper, we provide the means for realizing this promise by identifying certain memory colors e.g., green grass, red, and blue sky and rendering each independently making use of the full gamut of the display media while identifying and maintaining flesh tones to their original intent. Further, a means is provided for extending the gamut of not just wide-gamut, but any display media by simply lowering the white point of the display.

52.5: Effect of Color Gamut Volume in Display on Image Preference

We measured image preference using paired comparison when varying the color gamut and maximum luminance of the display to investigate the effect of color gamut volume on image preference. There is a trade-off relationship between the area of color gamut and luminance on image preference.

67.1: Evaluation of Gamut‐Expansion Algorithms for Wide‐Gamut Display

Different gamut expansion algorithms were applied to sRGB images and evaluated using paired comparison on image preference. Two performed better regardless test scenes. Image preference was highly correlated to lightness contrast, and there is a preferable range in the degree of chroma enhancement.