The Embedded Block Coding with Optimized Truncation in 嵌入式块优截断编码.pptVIP

The Embedded Block Coding with Optimized Truncation (EBCOT) in JPEG2000 JPEG2000 Codec Wavelet Compression The JPEG2000 Encoder Quantization The quantization operation is defined by the step size parameter, ,through Here, denotes the samples of sub-band , while denotes their quantization indices. The step size for each sub-band is specified in terms of an exponent, , and a mantissa, , where From “Sub band” to “code block” to “bit stream” EBCOT Layered Formation The Concept of EBCOT Bit-Plan Coding Primitives Zero Coding Run Length Coding Sign Coding Magnitude Refinement Coding Fractional Bit-Planes and Scanning Order Significance Propagation Pass Magnitude Refinement Pass Cleanup Pass Sub-bank and Code Block and sub-block Generally, Code Block size is 64*64 or 32*32 and sub-code block size is 16*16. The scanning order of the sub block to be used. Each code block is coded independently. Significant Significance:當一個係數bit-plane 的值，第一次由０變為１，則此 時這個係數將變為Significance。 Refinement:當一個係數已經是Significance，則這個係數接下來的 bit皆稱之為Refinement。 Sign:即係數的符號值。 The Bit Plan Coding Primitives Scan coding Four Types of Coding Operation for Bit Plan Coding Zero Coding Used to code new significance. Run Length Coding Reduce the average number of symbols needed to be coded. Sign Coding Used to code the sign right after a coefficient is identified significant. Magnitude Refinement Coding 3 context depending on the significance of its neighbors and whether it is the first time for refinement. Stripe Oriented Scanning Pattern Followed Within Each Coding Pass Zero Coding Run Length Coding Specifically, each of the following conditions must hold: 1) Four consecutive samples must all be insignificant. 2) The samples must have insignificant neighbors. 3) The samples must reside within the same sub-block Example for RLC Sign Coding 當symbol由insignificance 變為significance，此時必須將送出該symbol 的sign值，而sign 值是由垂直及水平鄰近點的sign 值和significance 來查表決定context states。 Magnitude R