Image Display—Mobile Imaging and Interactive Image Processing

Abstract

Abstract This chapter is about mobile image processing using subpixel rendering techniques to achieve superior sharpness for mobile displays by controlling individual subpixels rather than pixels. Subpixel rendering techniques take advantage of the fact that a single pixel on a color mobile display consists of several primary colors, typically three colored stripes (subpixels) ordered red, green, and blue (RGB). Researchers found that, by controlling the subpixel values of neighboring pixels, it is possible to micro-shift the apparent position of a line to gives greater details of text. However, the increased apparent luminance resolution often comes at the price of color fringing artifacts. A major challenge is to suppress chrominance distortion while maintaining apparent luminance sharpness. We start by introduction of subpixel arrangement in mobile display, with emphasis on the conventional RGB stripe display and other special dedicated subpixel layout mobile display. Then several down-sampling (both pixel and subpixel-based) schemes for mobile image displaying are presented. To better understand different characteristics of pixel and subpixel-based down-sampling schemes, a frequency domain analysis approach is introduced to explain why it is possible to achieve a higher apparent resolution using subpixel techniques. The theoretical analysis shows that the cut-off frequency of the low-pass filter for subpixel-based decimation can be effectively extended beyond the Nyquist frequency using novel anti-aliasing filters.