Image Signal Processor Scaler Memory Bandwidth Optimization
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Solution Overview
Problem
Conventional image signal processors experience significant delays and require high memory bandwidth due to frequent memory accesses, especially when processing high-definition images or in picture-in-picture modes, where large data quantities necessitate multiple memory accesses.
Innovation Solution
The image signal processor directly transmits input signals to noise removal or scaling units without passing through memory, reducing the image size when necessary, and stores the processed signals in memory, allowing for reduced memory accesses and lower bandwidth requirements by reading and writing single lines of video data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the scaler simultaneously reads multiple lines of video data from memory for a single memory access, then the image processing speed is improved, but the memory bandwidth requirement increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the required number of lines to be read from memory based on the scaling ratio before the actual scaling operation. This allows the system to optimize memory access patterns in advance, reading exactly the necessary amount of data without requiring excessive memory bandwidth during the critical scaling process.
Solution Approach 2:
The patent implements dynamics by making the number of lines read from memory variable rather than fixed. The system dynamically adjusts the line count based on the scaling ratio, reading more lines when downscaling and fewer lines when upscaling or maintaining size. This dynamic adaptation allows efficient use of memory bandwidth while maintaining processing speed.
2Productivity
If frequent memory accesses are performed to process high-definition image signals, then the image processing capability is improved, but the processing delay increases
Solution Approach 1:
The patent reduces processing delay by performing preliminary actions: calculating the scaling ratio, determining the number of lines to read, and preparing memory access patterns before the actual image processing begins. This pre-computation minimizes the time required during the critical processing phase, enabling high-definition image processing without excessive delays.
3Quantity of substance
If the image size of the input signal is reduced before storage, then the memory bandwidth requirement is reduced, but the image quality may be compromised
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the number of lines read from memory based on the scaling ratio. When downscaling, it reads multiple lines and processes them appropriately; when upscaling or maintaining size, it reads fewer lines. This parameter adaptation ensures that memory bandwidth is optimized without compromising image quality, as the processing is tailored to the specific scaling requirements.
Data Source
AI summary
An image signal processor for processing an input image signal to output an output image signal includes an input unit receiving the input image signal, a noise removal unit removing noise from the input image signal, and a scaler reducing, maintaining or magnifying the image size of the input image signal. The scaler directly receives the input image signal from the input unit or the noise removal unit in response to a route control signal, reduces the image size of the input image signal when the image size of the input image signal is larger than the image size of the output image signal and stores the image signal with a reduced image size in a memory. The scaler maintains or magnifies the image size of the image signal stored in the memory and outputs the image signal with a maintained or magnified image size as the output image signal.