Mobile Multi-level Adaptive Block Truncation Coding for Small-size Displays

We developed mobile multi-level adaptive block truncation coding (BTC) that reduces the size of the mobile source driver's embedded RAM by 3/4 (for VGA screen with QVGA-size memory). The BTC suppresses border artifacts,especially in images shown in windows of PCs,and it corrects jagged edges in natural images. It also improves the PSNR by approximately 6.6 dB compared with that of conventional quad decimation for natural images. Our BTC enables the suppression of artifacts using: (1) trimmed averaging for three-level representative values and (2) adaptive scheme selection (two- or three-level).