Because displays account for a large fraction of the power dissipation in smart watches, mobile phones, and tablets, it is important and interesting to develop techniques to reduce display power dissipation.
Crayon is a facility that can be inserted transparently into an operating system’s user interface pipeline, or applied offline to application assets. Crayon reduces display power dissipation when users accept trading display quality for longer battery life. Crayon works by exploiting three fundamental properties: The limited ability of humans to resolve small changes in shape and color, the image-content-dependence of the power dissipation of new display technologies such as DLP pico-projectors and OLED displays, and the low cost of computation relative to display power savings.
We have implemented and evaluated Crayon in three contexts: a hardware platform with detailed power measurement facilities and an OLED display, an Android tablet, and a set of cross-platform tools. Our results show that Crayon’s color transforms can reduce display power dissipation by over 66% while producing images that remain visually acceptable to users. The measured whole-system power reduction is approximately 50%. We quantify the acceptability of Crayon’s shape and color transforms with a user study involving over 400 participants and over 21,000 image evaluations.
Status: This is an ongoing project. If you are interested in collaborating on some of the unsolved problems or applications, please get in touch!
Collaborations: This is joint work with Virginia Estellers (UCLA) and Martin Rinard (MIT).
P. Stanley-Marbell, V. Estellers, and M. Rinard "Crayon: Saving Power through Shape and Color Approximation on Next-Generation Displays", In 11th Annual European Conference on Computer Systems, (EuroSys'16), April 2016. [Download PDF]
P. Stanley-Marbell and M. Rinard. "Perceived-Color Approximation Transforms for Programs that Draw". In IEEE Micro, vol. 38, no. 4, pp. 20-29, July/August 2018.
Mobile device screens account for up to half of the energy usage in mobile computing devices such as phones and tablets. Today, these displays are increasingly based on organic light-emitting diode (OLED) technology, whose energy usage depends on color content. At the same time, human color perception varies across the gamut of colors that a display can generate. This article is the first demonstration of using information for a large-scale study of human color perception to improve the energy efficiency of OLED (and related) displays.
J. Cambronero, P. Stanley-Marbell and M. Rinard. "Incremental Color Quantization for Color-Vision-Deficient Observers Using Mobile Gaming Data". Preprint, February 2018.
Color images account for an important fraction of the data stored on computers and mobile devices. The methods by which these data are compressed ultimately depend on a method for specifying the distinct colors that make up the palette of the compressed image. Today, this color quantization is oblivious to the different color perception acuities of individuals who store or view images. This article presents the first of its kind method for color quantization tuned to the color perception of color-vision-deficient observers and builds on the largest-scale study of human color perception of its kind.