Rate-distortion estimation for fast JPEG2000 compression at low bit-rates

Abstract

In JPEG2000 block coding, all coding passes are generated before rate allocation is performed among code-blocks. Unwanted passes are then discarded. For low bit-rate coding, this results in discarding of a large number of coding passes. In this letter, we propose a rate-distortion estimation method that enables pre-compression rate-distortion optimization to be carried out, wherein only the required passes need to be coded. Experiments using the proposed technique demonstrate speedup factors ranging from 1.17 to 1.78 at 0.0625 bpp, for JPEG2000 compression. Introduction: JPEG2000 is a current standard for image compression. An important feature of JPEG2000 is state-of-the-art low bit-rate performance in terms of decoded image quality [1]. Requirement of efficient low bit rate implementation for JPEG2000 compression is therefore of paramount importance. Block coding in JPEG2000 is based on Embedded Block Coding with Optimized Truncation (EBCOT) [2]. EBCOT operates on small blocks of quantized subband data called code-blocks, in terms of fractional bit-planes called coding passes, to generate coded sub-bit-streams. EBCOT achieves compression by discarding less important coding passes from each sub-bitstream such that the distortion is minimized while the target rate is met. At low

Enhanced Quality Scalability for JPEG2000 Code-Streams by the Characterization of the Rate-Distortion Slope

“…With the aim to reduce the computational load of the tier-1 coding stage when applying the PCRD method, more than 26 different ratedistortion optimization methods have been proposed in the last five years. Some of them are [6,7,8,9,10,11,12] (an extensive review and comparison among several methods can be found in [1]).…”

“…Therefore, the rate control method should concatenate the coding pass MRP of a code-block with the following CP. We explain this characteristic using the rate-distortion model from [9], which estimates the decrement in distortion and the increment in bit-rate of a code-block at the bit-plane p according to…”

“…This assumption relies on the meaningful difference between the large decrement in distortion, compared to the small increment in bit-rate, when a significant coefficient is encoded. For coding passes of type SPP and CP, the rate-distortion model proposed in [9] estimates this according to D = Nsig(2 p ) 2 R = 2Nsig + Ninsig and, although the encoding of a significant coefficient increases twice the estimated bit-rate of the encoding of an insignificant coefficient, D is decremented by (2 p ) 2 ! Therefore, it is expected that, as more significant coefficients are encoded in a coding pass, greater its ratedistortion slope is, specially at high bit-planes.…”

A Novel Approach to Sparse Histogram Image Lossless Compression Using Jpeg2000

“…In literature, there are several proposal of approaches that modify only the coder (thus preserving the standard compatibility [14][15][16][17][18][19][20][21][22][23][24][25][26]) or both the coder and the decoder. Our approach belongs to the second group and the gain over the standard will be motivated from a theoretical point of view (by definition of a gain function, see Section 4.2) and by the experimental results.…”

Adjusting the positions of truncation points for JPEG2000 compression

“…There is still much improvement space for JPEG2000 due to its open architecture. The optimality of context quantization of context-adaptive arithmetic coding is explored in [3,4]; [5,6] are absorbed in the speed-up of the bitplane coding (Tier1 coding) and optimized truncation (Tier2 coding) in JPEG2000.…”