A frequency adaptive line compression system for mobile display devices

Abstract

Abstract:The high resolution of the latest high-performance mobile display devices has resulted in an increase in the main frame buffer size and related bandwidth, and this is one of the main causes of a reduced battery life. As a means to solve this problem, one-dimensional line-based compression methods have been studies in order to be implemented in the limited chip design environment of the mobile display driver ICs. Conventional lossless compression techniques do not have a high compression ratio enough for complex images to ensure a sufficient power reduction. On the other hand, a wavelet-based 1D SPIHT method has been studied for use as a lossy-compression method with a high compression ratio while keeping the image quality. However, this method requires large hardware resources due to the performance for iterative calculations and sorting process. This paper proposes a novel wavelet-based lossy compression system that can achieve high compression and image quality while maintaining low complexity. The Frequency Adaptive Line Compression composed of 4-level DWT, horizontal predictive coding for the low-frequency regions, frequency selective zerozone quantization for high-frequency regions, and frequency component entropy coding. Experimental results confirmed that the proposed technique could achieve a higher compression ratio than the one required of conventional lossless compression methods and could also be implemented with a significantly less complexity than the conventional SPIHT method at the same compression ratio.

An energy-efficient low-memory image compression system for multimedia IoT products

“…The proposed compression method includes a compression method for compressing a single frame image and a bit rate control method for maintaining compression ratio and consistency of image quality through the image. This method extends and improves the existing frequency adaptive line compression (FALC) technique of Kim et al [27], achieving a higher compression ratio by using the least possible amount of processing and memory. The proposed technique adopts 2D DWT and 2D directional adaptive differential pulse code modulation (DPCM) between lines.…”

“…Kim et al [27] have proposed a frequency adaptive line compression (FALC) method with decreased complexity comparing to existing compression methods. Instead of using bit planes of RGB data, FALC method uses whole coefficients of discrete wavelet transforms of YCuCv color space data.…”

“…For 2D DWT in the 2L mode, a vertical DWT followed by the existing horizontal I42 integer DWT [27] to further remove vertical redundancy between two adjacent lines of an image. To have the minimum system complexity, Haar DWT [32] is used for vertical DWT.…”

“…They achieved a compression ratio of 3:1. Kim et al [27] have also presented a compression system that can perform horizontal predictive coding for low-frequency band with zero-zone scalar quantization techniques for higher frequencies after a line-based four-level discrete wavelet transform (DWT). After applying variable length coding method, they achieved a compression ratio of approximately 3:1 with a visually lossless condition.…”

A Consistent Quality Bit Rate Control for the Line-Based Compression

“…The frequency adaptive line compression (FALC) algorithm recently proposed by Kim et al [7] is one of the line-based compression techniques for display devices. However, there are no BRC schemes like FALC, and an optimized BRC was used in FALC.…”