CMOS Image Sensor Sunspot Removal via Reset Sampling Threshold
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Solution Overview
Problem
Existing methods for removing sunspots from CMOS image sensors are prone to misjudgment and introduce noise, with digital methods being inaccurate and analog methods causing excessive noise by replacing reset sampling levels with fixed values.
Innovation Solution
A method and apparatus that obtain reset sampling signal values, compare them to a predetermined threshold, generate location information for values below the threshold, and replace them with the maximum image brightness value to accurately remove sunspots without using fixed level values, thereby reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital method is used to remove sunspot by adjusting brightness value, then sunspot removal is achieved, but misjudgment occurs and accuracy deteriorates
Solution Approach 1:
The patent changes the parameter used for sunspot detection from brightness value adjustment to reset sampling signal voltage threshold comparison. By monitoring the reset sampling signal voltage and comparing it with a predetermined threshold, the system accurately identifies sunspots without misjudging black objects, thereby improving both reliability and measurement precision simultaneously
Solution Approach 2:
The patent replaces the digital image processing approach (mechanical system of adjusting brightness values) with an electrical signal-based approach. By using voltage threshold comparison of the reset sampling signal, the system achieves accurate sunspot detection without the misjudgment problems inherent in digital brightness adjustment methods
2Reliability
If analog method is used to remove sunspot by replacing reset sampling level with fixed level, then sunspot removal is achieved, but noise increases excessively
Solution Approach 1:
Instead of replacing the reset sampling level with a fixed level (which introduces noise), the patent changes the approach to using threshold comparison logic. The system compares the reset sampling signal voltage with a predetermined threshold and selectively processes only those pixels exceeding the threshold, thereby removing sunspots without introducing excessive noise to the sampling circuit
Solution Approach 2:
The patent creates a logical copy of the reset sampling signal through threshold comparison rather than physically replacing it with a fixed level. This allows the original signal to be preserved for non-sunspot areas while only the identified sunspot pixels are corrected, avoiding the noise introduction problem of fixed level replacement
Data Source
AI summary
A method for removing a sunspot of an image sensor, an apparatus for removing a sunspot of an image sensor and an image sensor are provided. The method includes: obtaining reset sampling signal values of pixel units in a pixel array of the image sensor; for each of the reset sampling signal values, determining whether the reset sampling signal value is less than a predetermined sampling signal threshold, and generating a comparing signal when the reset sampling signal value is less than the predetermined sampling signal threshold; generating location information of the pixel unit corresponding to the reset sampling signal value according to the comparing signal; and replacing the reset sampling signal value corresponding to the location information with a maximum brightness value.