Image compression method based on wavelet transformation

Abstract

The invention relates to a wavelet transformation image compression method, which is composed of the following steps. First, do the wavelet transformation to the digital image to get the wavelet coefficients. Second, each wavelet coefficient is divided by a quantization coefficient. Third, divide the wavelet coefficients into blocks according to its subband position. Fourth, scan every coefficient block along the level. During the scanning, each wavelet coefficient is classified into 13 types according to the significance of the peripheral wavelet coefficients, the sign of the coefficients, the refining and general output. The arithmetic coding is used according to the different distribution model. The invention may cancel the OT procedure, and decrease the needed number of the operating period and the coding system delay. The relative stability of the image quality is guaranteed during the coding procedure. And the coding symbol number is decreased to reduce the pressure on the binary arithmetic encoder.

Description

Technical field: [0001] The invention belongs to the field of information technology, and in particular relates to a digital image compression coding method based on wavelet transform. Background technique: [0002] At present, the digital image compression coding methods of wavelet transform all adopt the JPEG2000 standard coding method. The EBCOT coding process in the JPEG2000 standard is as follows: The wavelet coefficients of the sub-bands are divided into coefficient blocks (JPEG2000 recommends dividing them into 64×64 or 32×32), and each block is first implemented with importance priority coding (EBC), and then realizes global optimal truncation (OT). In order to realize importance-first coding, after each block of wavelet coefficients is represented by the original code, the highest bit is the sign bit (0 is positive, 1 is negative), and the other bits are the absolute value of the coefficient. The set of the same bit in the absolute value of the coefficient is calle...

AI Technical Summary

Problems solved by technology

However, this greatly increases the number of clock cycles required for encoding, and the use of global OT increases the theoretical delay of the encoding system. In addition, although this approach can accurately control the bit rate of each individual image, there is no effective method Stable control over the quality of image sequences composed of multiple images

[0004] The EBCOT encoder is the core of the JPEG2000 encoder. Since each bit plane is encoded layer by layer, and each bit plane needs to be scanned three times, the encoding process is very time-consuming, especially in the hardware implementation process. Especially many, far exceeding the wavelet transform part and the arithmetic coding part, becoming the bottleneck of the entire JPEG2000 coding system

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