cv2.imwrite doesn't save result image but initial only-CodePudding

I have a code:

import cv2
import numpy

background = numpy.zeros((1080, 1920, 3))
img = numpy.ones((255, 465, 3))
offset = numpy.array((12, 12))

x_offset = offset[0]
y_offset = offset[1]

img_w = img.shape[1]
img_h = img.shape[0]

background_w = background.shape[1]
background_h = background.shape[0]

x = x_offset
y = y_offset
for i in range(0, 16):
    background[y:y   img.shape[0], x:x   img.shape[1]] = img
    x  = img_w   x_offset
    if x > background_w - img_w:
        x = x_offset
        y  = img_h   y_offset

cv2.imshow("test", background)
cv2.imwrite("background.jpg", background)
cv2.waitKey(0)
cv2.destroyAllWindows()

that generates grid like this one:

So cv2.imshow shows the grid but cv2.imwrite writes only initial black background not the grid for some reason. How to fix that?

CodePudding user response：

You need to scale the color channels:

~~cv2.imwrite("background.jpg", background)~~

cv2.imwrite("background.jpg", background * 255)

Alternatively you can create a "white" image with type uint8:

~~img = numpy.ones((255, 465, 3))~~

img = numpy.ones((255, 465, 3), dtype = numpy.uint8) * 255