OpenCV Note

GaussianBlur()

cv.GaussianBlur(img, (5,5) , cv.BORDER_DEFAULT)

Blurring an image

The pixel is reduced to follow the average value of the pixels that is covered by the kernel size.

Canny()

It is used to detect edges in an image.

canny = cv.Canny(blur, 125, 175)
# 125 is the lower threshold value in Hysteresis Thresholding
# 175 is the upper threshold value in Hysteresis Thresholding
cv.imshow('canny', canny)
cv.waitKeyEx(0)

resize()

resized = cv.resize(img, (500,500), interploation = cv.INTER_AREA)
# interploation = cv.INTER_AREA This makes the image get resized smaller than original dimension.
cv.imshow(resized)

Cropping Image

cropped = img[50:200, 200:400]