OpenCvSharp (C# OpenCV) two-dimensional code distortion correction -- based on perspective transformation (with source code)

guide

    This article mainly introduces how to use the perspective transformation in OpenCvSharp to realize the distortion correction of the two-dimensional code.

    Since the QR code posted in the CSDN article will cause the display to fail, you can directly click the link below to view the picture:

    C# OpenCV implements two-dimensional code distortion correction-based on perspective transformation (detailed steps + code)

Implementation steps

     Before explaining the implementation steps, first look at the effect (the left is the original picture, and the right is the corrected effect):

【1】Demand Analysis

 

    Due to the shooting angle of the camera, the shape of the QR code is not a rectangle, and there is obvious distortion. We want to correct it to a normal rectangular or square pattern for easy decoding or other image processing.

    The preliminary processing steps are as follows:

① Find part of the outline of the QR code through preprocessing;

② Find the four corners of the QR code by contour analysis;

③ Based on the found four corner points, use perspective transformation to correct the QR code.

[2] Demonstration of implementation steps

① Segment the QR code area by simple binarization, because the target is black and the background is high