Image Sensor Calibration Using Blockwise Color Ratios for Edge Defects
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Solution Overview
Problem
Image sensors often experience poor pixel sensitivity in the edge areas, leading to a greenish phenomenon in low-illuminance environments due to their physical configuration, which existing technologies have not adequately addressed.
Innovation Solution
A method and apparatus for calculating calibration data involves generating color images from a raw image, dividing them into pixel blocks, calculating color ratios, and applying conversion ratios to correct defective pixels, thereby improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the image sensor uses a physical configuration with module lens, then the image sensor can capture optical images, but pixel sensitivity deteriorates in edge areas causing greenish phenomenon
Solution Approach 1:
The patent applies local quality by calculating different conversion ratios for different regions (center vs. edge areas) of the image sensor. The conversion ratio calculation is divided into first conversion ratios for center area pixel blocks and second conversion ratios for edge area pixel blocks, allowing each region to have optimized calibration parameters that compensate for its specific sensitivity characteristics.
Solution Approach 2:
The patent changes the parameter of conversion ratio based on the position of pixel blocks in the image array. By dynamically adjusting conversion ratios according to whether pixel blocks are located in center or edge areas, the system compensates for physical configuration differences and eliminates the greenish phenomenon without altering the physical sensor structure.
2Ease of manufacture
If calibration data is calculated using conventional methods, then the processing is simple, but image quality deteriorates due to inability to correct edge area defects
Solution Approach 1:
The patent segments the image array into multiple pixel blocks and further divides them into center area pixel blocks and edge area pixel blocks based on their positions. This segmentation allows the calibration process to treat different regions differently, applying appropriate conversion ratios to each segment to maintain both processability and image quality.
Solution Approach 2:
The patent performs preliminary action by pre-calculating conversion ratios for different pixel block positions before actual image processing. The calibration data is prepared in advance with different conversion ratios stored for center and edge areas, so that during actual image capture, the appropriate ratios can be applied immediately without complex real-time calculations.
Data Source
AI summary
An apparatus for calculating calibration data for an image sensor includes: a color image generator configured to receive a raw image from an image sensor and generate a plurality of color images by dividing a raw image by color; an area divider configured to divide each of the plurality of color images into pixel blocks, each pixel block having a preset size; a color ratio calculator configured to compare a reference color image with at least one non-reference color image and calculate color ratios for each pixel block of the at least one non-reference color image, the reference color image having a preset reference color and the at least one non-reference color image without having the preset reference color; and a conversion ratio calculator configured to calculate conversion ratios for each pixel block of the at least one non-reference color image using the color ratios for each pixel block.