CODEWITHSUNDEEP
pythonopencvrgb
Yash Patil
Yash Patil

Reputation: 25

How to convert 3 channeled image to 1 channeled image without using cv2.cvtColor()?

So, I have been asked to convert a BGR image to GRAYSCALE using weighted mean of each pixel.

img = cv2.imread('..\\Images\\horse.jpg',-1)
height = img.shape[0]
width = img.shape[1]
gray = img.copy()
for x in range(img.shape[1]):
  for y in range(img.shape[0]):
     gray[y][x]= (0.11 * img[y][x][0] + 0.6 * img[y][x][1] + 0.3 * img[y][x][2])



print(gray)
print(gray.shape)
cv2.imshow('gray',gray)
cv2.waitkey(0)

Shape of the resultant image:

(404, 640, 3)

it should be a single channeled image right? In result the image shown is GRAYSCALE but still it is a 3 channeled image, can anyone help me with that?

Upvotes: 1

Views: 401

Answers (1)

Anwarvic
Anwarvic

Reputation: 12992

The reason is so simple, this happens because you copied the whole img at the beginning which has three channels. You need to copy just one channel like so:

gray = img[:, :, 0].copy()

Upvotes: 1

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