Computer vision: opencv (2) image enhancement, denoising, recognition

Grayscale

The method of converting the image to gray is to operate on the pixel value of the image, and assign the different component values ​​of the three channels and three pixels to the same value, thus realizing the grayscale transformation.
There are several methods of grayscale:
1. Floating point algorithm: Gray=R0.3+G0.59+B0.11
2. Integer method: Gray=(R30+G59+B11)/100
3. Shift method : Gray =(R76+G151+B*28)>>8;
4. Average method: Gray=(R+G+B)/3;
5. Only green: Gray=G;

grayscale transformation

Gray scale transformation has线性变换、非线性变换、分段线性变换

1. Image grayscale upshift transformation: DB=DA+50
2. Image contrast enhancement transformation: DB=DA*1.5
3. Image contrast reduction transformation: DB=DA*0.8
4. Image grayscale inverse color transformation: DB=255-DA
5. Image contrast enhancement transformation: DB=DA×DA/255
6. Image grayscale logarithmic transformation
7. Image grayscale gamma transformation
8. Thresholding
   

smooth denoising

Image smoothing includes: 均值滤波、方框滤波、高斯滤波、中值滤波
Gaussian smoothing
Median filtering

Line detection

intersection detection

shape recognition

digital identification

License Plate Recognition

face recognition