Chrominance Quantization Parameter Range Adjustment for Variable Bit Depth
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Solution Overview
Problem
The H.264 video encoding standard limits the range of chrominance quantization parameters when luminance and chrominance signals have different bit depths, restricting the quality control of chrominance signals during image encoding and decoding.
Innovation Solution
An image encoding and decoding system that generates chrominance quantization parameters based on the difference in bit depths between luminance and chrominance signals, expanding the range of usable values for chrominance quantization parameters to improve image quality control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the chroma_qp_index_offset code range is limited to -12 to +12 in H.264, then the encoding complexity is reduced, but the range of usable chrominance quantization parameter values becomes drastically reduced when luminance and chrominance bit depths differ
Solution Approach 1:
The patent makes the chroma_qp_index_offset range dynamic by adjusting it according to the difference between luminance and chrominance bit depths. When bit depths differ, the range is expanded beyond the fixed -12 to +12 limitation, allowing chrominance quantization parameters to be properly controlled across different bit depth configurations while maintaining encoding efficiency.
Solution Approach 2:
The patent changes the parameter range of chroma_qp_index_offset based on the bit depth difference between luminance and chrominance signals. By dynamically adjusting the offset range according to bit depth configuration, the system enables broader chrominance quantization parameter control without significantly increasing encoding complexity.
2Manufacturing precision
If the chroma_qp_index_offset range is expanded to increase chrominance quantization parameter control, then image quality control is improved, but encoding complexity increases
Solution Approach 1:
The patent adjusts the chroma_qp_index_offset range as a parameter change based on bit depth differences. This allows precise control of chrominance quantization parameters for different bit depth configurations (8-bit, 10-bit, 12-bit) without requiring a complete redesign of the encoding system, thus improving image quality control with minimal complexity increase.
Solution Approach 2:
By making the offset range dynamic rather than fixed, the system adapts to different bit depth scenarios only when needed. This dynamic adjustment provides fine-grained image quality control for chrominance signals while keeping the encoding process simple for standard configurations.
Data Source
AI summary
A luminance signal of an image and a chrominance signal of a bit depth different from that of the luminance signal is input, a luminance quantization parameter used to quantize the input luminance signal in block units is generated, a chrominance quantization parameter used to quantize the input chrominance signal in block units within a range depending on the luminance quantization parameter is generated, the input luminance signal is quantized by the luminance quantization parameter, the chrominance signal is quantized by the chrominance quantization parameter, and the range is changed depending on the difference between the bit depth of the luminance signal and the chrominance signal during the generation of the chrominance quantization parameter.