A column shading correction method for CMOS image sensor and CMOS image sensor

By selecting node columns in the CMOS image sensor, fitting the shading curve and correcting the image data, the dark level correction deviation problem caused by column shading is solved, and better image quality and smaller chip consumption are achieved.

CN114765668BActive Publication Date: 2025-02-07CHENGDU LIGHT COLLECTOR TECH
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Patent Information

Application Number
CN202110037427.9
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2021-01-12
Publication Date
2025-02-07
Estimated Expiration
2041-01-12

AI Technical Summary

Technical Problem

The column shading of existing CMOS image sensors will cause dark level correction deviations, resulting in local color casts on the image.

Method used

By selecting several node columns, reading the black-blocking row data, fitting a shading fitting curve, and correcting the image data based on the curve, subtracting the correction difference value to obtain the corrected image data.

Benefits of technology

It effectively reduces the shading in the column direction, improves image quality, reduces the requirements for layout parasitics and chip area consumption, and can adaptively adjust the shaded curve to adapt to different gain conditions.

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Abstract

The present invention provides a column shading correction method for a CMOS image sensor and a CMOS image sensor, the correction method comprising the following steps: S1: selecting a number of node columns according to the number of columns of a pixel unit of the CMOS image sensor; S2: reading the first frame black-masked row of the pixel unit upon power-on, and obtaining the values ​​of the black-masked rows corresponding to the several node columns; S3: obtaining a shading fitting curve whose abscissa is the number of columns and ordinate is the value of the black-masked row according to the values ​​of the node columns and the corresponding black-masked rows; S4: reading the image row of the CMOS image sensor upon power-on, and performing correction processing on the output image data according to the shading fitting curve to obtain the corrected image data. The column shading correction method for a CMOS image sensor and the CMOS image sensor provided by the present invention can solve the problem in the prior art that the column shading of the CIS will cause a dark level correction deviation, thereby causing a local color cast on the image screen.
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Citation Information

Patent Citations

  • Analog row black level calibration for cmos image sensor

    CN102647566A

  • Algorithm used for black level correction of CMOS (Complementary Metal Oxide Semiconductor) image sensor and system thereof

    CN104333717A