Shape Adaptive All Phase Biorthogonal Transform and Its Application in Image Coding

Abstract

In this paper shape adaptive all phase biorthogonal transform (SA-APBT) for coding arbitrarily shaped image segments is proposed. The proposed transform can be used in region-based image compression instead of the shape adaptive discrete cosine transform (SA-DCT). Region-based image coding method is made up of three procedures: image segmentation, contour coding and texture coding. An image is divided into region-of-interest (ROI) and background area by image segmentation. Both areas are encoded and decoded independently. Experimental results on test images show that compared with SA-DCT at the same bit rates, the PSNRs and visual effects of reconstructed images based on SA-APBT are comparable to the one based on SA-DCT especially at low bit rates. And the SA-APBT transform coefficients are quantized uniformly, while the SA-DCT transform coefficients are quantized according to different quantization steps in the quantization table. So the quantization based on SA-APBT is simpler and computational complexity is reduced. Index Terms-image coding, discrete cosine transform (DCT), all phase biorthogonal transform (APBT), shape adaptive, region-of-interest (ROI)

Color Image Coding Based on Shape-Adaptive All Phase Biorthogonal Transform

“…Similar to SA-DCT [11], SA-APBT can be used in region-based gray image coding [12] and MPEG-4 video compression [13]. There are four procedures for SA-APBT: vertically shift the pixels to be transformed to the uppermost position, one-dimensional variable-length APBT in the vertical direction, horizontally shift the pixels to the left border, and one-dimensional variable-length APBT in the horizontal direction.…”

“…However, the disadvantage of the region-based image coding using SA-DCT is the serious blocking effects at low bit rates. To solve this problem, this paper proposes a color image coding algorithm based on shape-adaptive APBT (SA-APBT) [12]. This algorithm is implemented with four procedures: color space conversion, image segmentation, shape coding, and texture coding.…”

Video Coding Based on Shape-Adaptive All Phase Biorthogonal Transform and MPEG-4

“…In H.263 quantization method, the mathematical expression of inverse quantization used by the DC coefficient of intra-coded block is also (9…”

“…Shape-Adaptive Discrete Cosine Transform (SA-DCT) [8] for arbitrarily shaped image segment coding is widely adopted and included in MPEG-4 standard because of low complexity and effective coefficients decorrelation. But the shortcoming of it is the serious blocking effects at low bit rates [9]. In order to solve this problem, this paper proposes video coding algorithm based on Shape-Adaptive All Phase Biorthogonal Transform (SA-APBT) and MPEG-4.…”

All Phase Biorthogonal Transform and Its Application in MPEG-4 Video Compression

“…DCT transform shows good characteristics in terms of energy compaction and coefficients decorrelation [5]. However, such techniques produce noticeable blocking artifacts along block boundaries and ringing artifacts near edges in the decompressed images especially at low bit rates.…”