如何用另一个数组的相同索引中的值替换一个数组中的值？

Question

I have two 3D numpy arrays which represent two images. The shape of each array is (1080, 1920, 3). The number 3 represents the RGB value of each pixel in the image.

My goal is to replace every non-black pixel in the first array to the value of the "parallel" pixel (in the same index) from the other array.

How can I do this using only numpy methods?

Answer 1

Use a mask with True/False values

# All pixels should be normalized 0..1 or 0..254
first_img = np.random.rand(1920,1080,3)
second_img = np.random.rand(1920,1080,3)

eps = 0.01  # Black pixel threshold
mask = first_img.sum(axis=2) > eps

for i in range(first_img.shape[2]):
    first_img[:,:,i] = (first_img[:, :, i] * mask) + ((1 - mask) * second_img[:, :, i])