Fixed-Ratio Compression of an RGBW Image and Its Hardware Implementation

In the latest large-screen TVs, an RGBW color domain is widely used to enhance the brightness of liquid crystal display (LCD) panels. As the correlations among RGBW color components are different from those among conventional RGB components, a compression algorithm developed for an RGB image may not be efficient for RGBW compression. For high-fidelity RGBW image coding, a novel prediction-based coding algorithm is proposed in this paper. The proposed algorithm is composed of two prediction steps that take advantage of spatial correlation and inter-color correlations, respectively. For residual coding, this paper proposes a fixed-ratio coding method based on Golomb-Rice coding. The proposed encoder is composed of two sub-coders: pre-coder and post-coder. The pre-coder estimates the length of the bitstream for various quantization levels. Based on that estimation, the appropriate quantization level is selected. The post-coder generates the final bitstream. Experimental results show that the average peak signal-to-noise ratio (PSNR) of the proposed algorithm is 51.16 dB. The throughput of the proposed encoder and decoder hardwares is 26.7 Gb/s, and their respective gate counts are 56.1 K and 39.6 K.