Defective pixel detecting and correcting method based on minimal mid-value gradient filtering

Abstract

The invention discloses a defective pixel detecting and correcting method based on minimal mid-value gradient filtering. The method comprises the steps that a 5*5 Bayer array uses a pixel to be detected as the center, a center pixel is used as the datum, three gradient absolute values are calculated in the horizontal direction, the vertical direction, the diagonal direction and the clinodiagonal direction, the mid-value of the gradient absolute values in each direction is gained, and then the minimum value of the four mid-values is obtained to be used as the edge direction, namely the defective pixel checkout direction; in the minimum mid-value gradient direction, a defective pixel can be obtained when the requirement that the middle gradient absolute value is larger than the value which is integer multiples of the sum of the other two gradient absolute values in the same direction is met, the pixel value in the direction is used for verification, and otherwise, the pixel is a normal pixel and is output directly; for certain special range pixels, a more strict judgment condition is used for reducing missing inspection at edge pixels; for the diagonal position or the back-diagonal position, a more loose judgment condition is used for reducing missing inspection at the edge position when the gradient meets certain conditions. By means of the defective pixel detecting and correcting method based on minimal mid-value gradient filtering, the defective pixel can be filtered out quickly, the false detection rate and the missing detection rate are low, and image borders can be completely reserved.

Description

technical field [0001] The invention belongs to the technical field of image processing, in particular to a method for detecting and correcting dead pixels based on minimum median gradient filtering. Background technique [0002] Due to the limitations of the image sensor manufacturing process, CMOS sensors have more or less dead pixels when they leave the factory. Moreover, after a CMOS lens is used for a long time, or in a high-temperature and long-exposure environment, there will be more and more dead pixels, which will greatly affect the image quality. The so-called dead pixels refer to extremely bright or extremely dark pixel values ​​that are always present at certain fixed positions regardless of the influence of external light. Dead pixels greatly affect the image quality and cause great discomfort to the viewer. The traditional dead point correction method is to record the position of the dead point and solidify it in the circuit in the form of a lookup table. Thi...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a method for detecting and correcting bad points based on the minimum median gradient filter, which aims to solve the existing dead point checking method, which does not work on the edge and will miss the bad point on the edge, or The edge is processed, but there is a problem with blurring the edge

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