image reading
cv2.imread(filename, flags)->Mat
The second parameter is a flag that specifies how to read the image.
cv.IMREAD_COLOR: Load a color image. Any image transparency is ignored. It is the default flag.
cv.IMREAD_GRAYSCALE: load the image in grayscale mode
cv.IMREAD_UNCHANGED: loaded image, including alpha channel
Note 1: In addition to these three flags, you can simply pass integers 1 , 0 or -1 respectively
Note 2: The 3 channels read by OpenCV are BGR
image display
cv2.imshow(winname, Mat)
cv2.waitkey(1000)
cv2.destroyWindows()
print(img)
cv2.imwrite(filename, img)
image conversion
Image conversion — to grayscale image
cv2.imread(filename, cv2.IMREAD_GRAYSCALE) #0
cv2.cvtColor(src, code)
Image conversion - binary image
cv2.imread(filename, cv2.IMREAD_GRAYSCALE) #0
cv2.threshold(src, thresh, maxval,type[,dst])
•
Among them ,
thresh
: the middle threshold, which can be
any value between
0
and
255 ;
maxval : the maximum threshold, which should be set to 255 ; type : the type of threshold algorithm, 0 means the conventional threshold algorithm, if the current pixel value is greater than thresh , modify it to maxval , otherwise, change to 0 .
Color separation and merging
cv2.split(m, mv)->mv• Among them, m is a multi-channel array; mv is a channel vector.
cv2.merge(mv, dst)->dst
•
Where
dst
: result map;
mv
is channel vector
Common image processing functions in OpenCV
cv2.imread()
cv2.imshow()
cv2.imwrite()
cv2.cvtColor()
cv2.threshold()
cv2.hstack(())
cv2.split()
cv2.merge()