Variable Length Coding for Quantization Matrix Difference Values
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Solution Overview
Problem
Conventional picture coding methods suffer from reduced efficiency due to fixed length coding of quantization matrix values, which leads to larger code lengths and decreased compression ratios.
Innovation Solution
A picture coding method that calculates and codes the difference values between quantization matrix frequency components and a predetermined value, using variable length codes with shorter lengths for smaller differences, and represents these differences as remainders of 2 raised to a power, allowing for more efficient coding and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fixed length coding is used for quantization matrix values, then coding simplicity is maintained, but code length increases and compression ratio decreases
Solution Approach 1:
The patent changes the coding parameter from fixed length to variable length based on the difference value between quantization matrix components. By calculating the difference from a predetermined value and using variable length codes where smaller differences get shorter codes, the system achieves better compression while maintaining decoding simplicity through the predictable coding pattern.
2Loss of information
If variable length codes are used for quantization matrix values, then compression ratio improves, but coding complexity increases
Solution Approach 1:
The patent performs preliminary calculation of difference values between quantization matrix components and predetermined values before coding. By pre-calculating these differences and representing them as remainders of 2 raised to a power, the system simplifies the subsequent variable length coding process and makes the coding pattern more predictable and manageable.
Solution Approach 2:
The patent transforms the quantization matrix values into difference values relative to predetermined values, and further represents these differences as powers of 2 remainders. This parameter transformation simplifies the variable length coding by creating a more structured and predictable code distribution pattern.
3Loss of information
If difference values are coded instead of original values, then code length shortens for small differences, but decoding complexity increases
Solution Approach 1:
The patent represents difference values as remainders of 2 raised to a power, creating a structured parameter transformation that simplifies both encoding and decoding. This mathematical representation allows the decoder to efficiently reconstruct original values by adding the predetermined value to the decoded difference, maintaining simplicity while achieving shorter code lengths for small differences.
Data Source
AI summary
The picture coding method according to the present invention is a picture coding method for coding a picture on a block-by-block basis through orthogonal transformation and quantization, and coding a quantization matrix that is used to derive quantization steps for frequencies of orthogonal transformation coefficients, the method comprising: calculating a difference value between each of frequency components included in the quantization matrix and a predetermined value corresponding to said each of the frequency components; and coding the difference value into a variable length code, wherein a code length of the variable length code is shorter as the difference value is smaller, or equal to a code length of a neighboring difference value of said difference value.