On-chip frame memory reduction using a high-compression-ratio codec in the overdrives of liquid-crystal displays

摘要

Abstract. Overdrive is commonly used to reduce the liquid-crystal re-nsponse time and motion blur in liquid-crystal displays (LCDs). However,noverdrive requires a large frame memory in order to store the previousnframe for reference. In this paper, a high-compression-ratio codec is pre-nsented to compress the image data stored in the on-chip frame mem-nory so that only 1 Mbit of on-chip memory is required in the LCD over-ndrives of mobile devices. The proposed algorithm further compresses thencolor bitmaps and representative values (RVs) resulting from the blockntruncation coding (BTC). The color bitmaps are represented by a lumi-nnance bitmap, which is further reduced and reconstructed using mediannfilter interpolation in the decoder, while the RVs are compressed usingnadaptive quantization coding (AQC). Interpolation and AQC can providenthree-level compression, which leads to 16 combinations. Using a rate-ndistortion analysis, we select the three optimal schemes to compress thenimage data for video graphics array (VGA), wide-VGA LCD, and standard-ndefinitionTV applications. Our simulation results demonstrate that the pro-nposed schemes outperform interpolation BTC both in PSNR (by 1.479 ton2.205 dB) and in subjective visual quality. C u00022010 Society of Photo-Optical Instru-nmentation Engineers. [DOI: 10.1117/1.3509370]