Unformatted histogram values

Question

I am trying to find the histogram values of an image by using my own function but when i run my code it prints the histogram values like [1.000e+00 4.000e+00 1.000e+00 8.000e+00 8.000e+00 2.500e+01 2.100e+01 4.500e+01 5.500e+01 8.800e+01 1.110e+02 1.220e+02 1.280e+02 1.370e+02 Is it normal or is there any other method that i can display histogram values in an understandable way? Here is my function;

import numpy as np
import cv2

def histogram(img):
    height = img.shape[0]
    width = img.shape[1]

    hist = np.zeros((256))

    for i in np.arange(height):
        for j in np.arange(width): 
            a = img.item(i,j)
            hist[a] += 1
        
    print(hist)

img = cv2.imread('rose.jpg', cv2.IMREAD_GRAYSCALE)
histogram(img)

Answer 1

Where you initialize your histogram, set its type to np.uint32 or similar since you can only ever have a whole, non-negative number of pixels of a given colour:

hist = np.zeros(256, dtype=np.uint32)

Check the type of your current array and find it is float64 with:

print(hist.dtype)

Hint: See also here.