import cv2 as cv


def compareImgs_hist_del(img1, img2):
    width, height = img1.shape[1], img1.shape[0]
    img2 = cv.resize(img2, (width, height))
    num_bins = 10
    hist1 = [0] * num_bins
    hist2 = [0] * num_bins
    bin_width = 255.0 / num_bins + 1e-4
    # compute histogram from scratch

    # for w in range(width):
    #     for h in range(height):
    #         hist1[int(img1[h, w] / bin_width)] += 1
    #         hist2[int(img2[h, w] / bin_width)] += 1

    # compute histogram by using opencv function
    # https://docs.opencv.org/4.x/d6/dc7/group__imgproc__hist.html#ga4b2b5fd75503ff9e6844cc4dcdaed35d

    hist1 = cv.calcHist([img1], [0], None, [num_bins], [0, 255])
    hist2 = cv.calcHist([img2], [0], None, [num_bins], [0, 255])
    sum = 0
    for i in range(num_bins):
        sum += abs(hist1[i] - hist2[i])
    return sum / float(width * height)