Image Encoding Apparatus Scene Change Detection Quantization Control
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Solution Overview
Problem
Conventional image encoding technologies face challenges in maintaining image quality during scene changes, especially when the correlation between frames is low, leading to unstable image quality and difficulty in detecting scene changes, which affects the control sensitivity of the quantization parameter Qp.
Innovation Solution
An image encoding apparatus that detects scene changes by inferring variations in the quantization parameter within a frame and switches the method for determining the quantization parameter after detection, using a first and second quantization control method to stabilize image quality and adjust the target code amount accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional quantization control is used to converge code amount to target, then code amount control is achieved, but image quality becomes unstable during scene changes
Solution Approach 1:
The scene change detection unit performs preliminary detection of scene changes by monitoring quantization parameter variations before encoding proceeds, allowing the system to proactively adjust control strategies rather than reacting after quality degradation occurs
Solution Approach 2:
The system implements feedback control by continuously monitoring quantization parameter changes and using this information to detect scene changes, then adjusting the quantization control method based on the detected scene change state to maintain stable image quality
2Productivity
If quantization parameter Qp is increased to reduce code amount, then compression ratio improves, but image quality degradation increases
Solution Approach 1:
The system dynamically adjusts the quantization parameter Qp based on detected scene changes, using first quantization control method during normal operation and switching to second quantization control method when scene changes are detected, allowing optimal balance between compression ratio and image quality under different conditions
Solution Approach 2:
The invention changes the quantization control strategy parameter based on scene change detection, switching between different control methods to optimize the trade-off between compression ratio and image quality for different scene conditions
3Productivity
If feed-back control is used for code amount control, then code amount convergence is achieved, but scene change detection becomes difficult when frame correlation is low
Solution Approach 1:
The system uses the quantization parameter as an intermediary indicator to detect scene changes, monitoring its variations as a proxy for detecting scene transitions without requiring direct frame comparison, which works effectively even when frame correlation is low
Data Source
AI summary
The invention generates encoded data in which image quality degradation of regions of the frame of interest that have not been encoded is suppressed. For this, an apparatus comprises a quantizing unit which quantizes image data of a frame in accordance with a quantization parameter, every predetermined block set in advance, an encoding unit which encodes quantized data, a quantization control unit which controls the quantization parameter such that a code amount approaches a target code amount, and a scene change detecting unit which detects a scene change. The quantization control unit has at least two control methods, applies a first quantization control method when starting encoding of a frame, and, in a case where the scene change detecting unit detects a scene change, switches to a second quantization control method from the first quantization control method.