Dynamic Range Compression for Image Decoding
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Solution Overview
Problem
Current image processing systems face challenges in reducing the information amount of background regions in images without compromising the peak signal-to-noise ratio (PSNR) or increasing compression ratio, especially in surveillance camera video signals, where artifacts in the background region are not a concern.
Innovation Solution
An image processing system that dynamically compresses the dynamic range of background regions using a predetermined coefficient, generating a low dynamic range image signal, which is then compressed using a coding scheme, while also including ROI information in the bit stream to optimize compression and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a low pass filter is used to reduce the information amount of the background region by decreasing amplitudes of high frequency components, then the information amount of the background region is decreased, but the PSNR of the background region deteriorates
Solution Approach 1:
The patent changes the parameter control approach from traditional low pass filtering to dynamic range compression. By applying a dynamic range compression unit with compression ratio α to the background region, the patent reduces the information amount while maintaining better PSNR compared to conventional low pass filtering methods. This parameter change allows efficient compression without significant quality loss.
2Loss of information
If parameter control function is added to the compression unit to decrease information amount of background regions, then the information amount is reduced, but the device complexity increases
Solution Approach 1:
The patent segments the image processing into distinct functional units: an ROI detection unit that identifies regions of interest, and a dynamic range compression unit that processes only the background regions. This segmentation allows the compression function to be added without complicating the entire compression unit, as the ROI detection and compression operations are separated into independent modules.
3Productivity
If compression ratio is increased by reducing information amount of background region, then the compression efficiency is improved, but the image quality deteriorates
Solution Approach 1:
The patent applies different processing qualities to different regions of the image. The ROI detection unit identifies important regions that require high quality preservation, while the dynamic range compression unit applies aggressive compression only to background regions where quality is less critical. This local quality approach allows overall compression ratio improvement while maintaining acceptable image quality in important areas.
Data Source
AI summary
To provide an image processing system and an image decoding apparatus that can limit compression ratio decrease and image quality deterioration and efficiently reduce an information amount.An image processing system that compresses and transmits an input image signal including pixel values corresponding to respective pixels, including: a dynamic range compression unit configured to compress, by a predetermined coefficient, a dynamic range of each of the pixel values corresponding to a background region other than a region of interest (ROI) designated as a desired region for the pixel values in an image based on the input image signal, to generate a low dynamic range image signal; a coding compression unit configured to compress the low dynamic range image signal in accordance with a predetermined image coding scheme to generate compressed image data; and a bit stream transmitter configured to output a bit stream signal including ROI information, the predetermined coefficient and the compressed image data.