How to fix error setting an array element with a sequence in python?-CodePudding

I am getting this error when I use the following code, how can I deal with it

TypeError Traceback (most recent call last)
TypeError: only size-1 arrays can be converted to Python scalars

The above exception was the direct cause of the following exception:

ValueError Traceback (most recent call last)
<ipython-input-20-e475e9fcaba7> in <module>
      17 ShowImage(img2)
      18
---> 19 main()

1 frame
<ipython-input-20-e475e9fcaba7> in image_downsampling(f, sampling_rate)
       8 for x in range(nr_s):
       9 for y in range(nc_s):
---> 10 g[x, y] = f[x*sampling_rate, y*sampling_rate]
      11 return g
      12

ValueError: setting an array element with a sequence.

Code:

import numpy as np
import cv2

def image_downsampling(f, sampling_rate):
  nr, nc = f.shape[:2]
  nr_s, nc_s = nr // sampling_rate, nc // sampling_rate
  g = np.zeros([nr_s, nc_s], dtype = 'uint8')
  for x in range(nr_s):
    for y in range(nc_s):
       g[x, y] = f[x*sampling_rate, y*sampling_rate]
  return g

def main():
  img1 = cv2.imread("Barbara.JPG", -1)
  img2 = image_downsampling(img1, 2)
  ShowImage(img1)
  ShowImage(img2)

main()

CodePudding user response：

The variable img1 is an image loaded from a file, I believe its shape is (m,n, 3) if its RGB.

So when you do g[x, y] = f[x*sampling_rate, y*sampling_rate] I believe you are putting a RGB pixel into a uint8 slot of the array g.

If you want to keep g a grayscale image, you should transform your rgb image into a grayscale one, or load it directly in grayscale mode

CodePudding user response：

You can transfer the correct shape to the new image like this:

g = np.zeros(f.shape, dtype = 'uint8')

But please note that you are implementing an existing function. This is doing the whole job:

g = cv2.resize(f, None, fx=1/sampling_rate, fy=1/sampling_rate)