I have an image represented by a numpy.array
matrix nxm of triples (r,g,b)
and I want to convert it into grayscale, , using my own function.
My attempts fail converting the matrix nxmx3 to a matrix of single values nxm, meaning that starting from an array [r,g,b]
I get [gray, gray, gray]
but I need gray
.
i.e. Initial colour channel : [150 246 98]
.
After converting to gray : [134 134 134]
.
What I need : 134
How can I achieve that?
My code:
def grayConversion(image):
height, width, channel = image.shape
for i in range(0, height):
for j in range(0, width):
blueComponent = image[i][j][0]
greenComponent = image[i][j][1]
redComponent = image[i][j][2]
grayValue = 0.07 * blueComponent + 0.72 * greenComponent + 0.21 * redComponent
image[i][j] = grayValue
cv2.imshow("GrayScale",image)
return image
Here is a working code:
def grayConversion(image):
grayValue = 0.07 * image[:,:,2] + 0.72 * image[:,:,1] + 0.21 * image[:,:,0]
gray_img = grayValue.astype(np.uint8)
return gray_img
orig = cv2.imread(r'C:\Users\Jackson\Desktop\drum.png', 1)
g = grayConversion(orig)
cv2.imshow("Original", orig)
cv2.imshow("GrayScale", g)
cv2.waitKey(0)
cv2.destroyAllWindows()
You can use a dot product:
gray_image = image.dot([0.07, 0.72, 0.21])
Or even just do the whole operation manually:
b = image[..., 0]
g = image[..., 1]
r = image[..., 2]
gray_image = 0.21 * r + 0.72 * g + 0.07 * b
Don't forget to convert back to 0-255:
gray_image = np.min(gray_image, 255).astype(np.uint8)
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