Cv2 not able to open tiff file in loop

Python
1

Hi!

I am running a code using the cv2 module to count red dots in images. All my files are in .tif format. Some images were dotted by myself, and others by another person. My problem is that my own images run without any problem, but the images that I received from the other person don’t work in the loop. However, if I open their images on the Idle interface command line it works without problem. I already re-saved the images in exactly the same program and when I look into the properties of the images they look exactly the same… Has anyone any idea what could be the problem? I attach below my code and interface commands. (python 3.10.4)

Thank you very much.

LOOP FILE:

import cv2
import numpy
import os
from os import listdir

# assign colors
red = [(0,0,220),(60,60,265)] # lower and upper 
dot_colors = [red]

 # get the path/directory
folder_dir = "C:/Users/x/OneDrive/Documents/test_photos"

for images in os.listdir(folder_dir):
    print(folder_dir)
    print(images)
    img = cv2.imread(images)
    # apply medianBlur to smooth image before threshholding
    blur= cv2.medianBlur(img, 5) # smooth image by 7x7 pixels, may need to adjust a bit

    for lower, upper in dot_colors:
        output = img.copy()
        # apply threshhold color to white (255,255, 255) and the rest to black(0,0,0)
        mask = cv2.inRange(blur,lower,upper) 

        circles = cv2.HoughCircles(mask,cv2.HOUGH_GRADIENT,1,20,param1=20,param2=8,
                                   minRadius=0,maxRadius=60)    
        index = 0
        if circles is not None:
            # convert the (x, y) coordinates and radius of the circles to integers
            circles = numpy.round(circles[0, :]).astype("int")

            # loop over the (x, y) coordinates and radius of the circles
            for (x, y, r) in circles:
                # draw the circle in the output image, 
                #   then draw a rectangle corresponding to the center of the circle
                cv2.circle(output, (x, y), r, (255, 0, 255), 2)
                cv2.rectangle(output, (x - 5, y - 5), (x + 5, y + 5), (255, 0, 255), -1)

                index = index + 1
                #print str(index) + " : " + str(r) + ", (x,y) = " + str(x) + ', ' + str(y)
            print(images)
            print('No. of circles detected = {}'.format(index))

output:

C:/Users/x/OneDrive/Documents/test_photos
AB2-3_A3.tif
AB2-3_A3.tif
No. of circles detected = 170
C:/Users/x/OneDrive/Documents/test_photos
AB2-3_B1.tif
AB2-3_B1.tif
No. of circles detected = 170
C:/Users/x/OneDrive/Documents/test_photos
FM2_C1.tif
Traceback (most recent call last):
  File "C:\Users\x\OneDrive\Documents\script_loop.py", line 21, in <module>
    blur= cv2.medianBlur(img, 5) # smooth image by 7x7 pixels, may need to adjust a bit
cv2.error: OpenCV(4.5.5) D:\a\opencv-python\opencv-python\opencv\modules\imgproc\src\median_blur.dispatch.cpp:283: error: (-215:Assertion failed) !_src0.empty() in function 'cv::medianBlur'

When I run the specific file in Idle shell it works fine:

image="C:/Users/x/OneDrive/Documents/test_photos/FM2_C1.tif"
img = cv2.imread(image)
print(img)
[[[ 88 136  68]
  [134 114  68]
  [181  94  47]
  ...
  [190 213 103]
  [236 208  51]
  [236 204   0]]

 [[ 85 158  68]
  [107  86  68]
  [130  85  47]
  ...
  [201 197 103]
  [245 191  51]
  [245 174   0]]

 [[ 83  91  39]
  [ 81  58  39]
  [ 79  57  27]
  ...
  [213 181  90]
  [255 162  45]
  [255 144   0]]

 ...

 [[ 78 116  52]
  [103  90  52]
  [128  68  49]
  ...
  [143  98  55]
  [156 108  58]
  [156  87  62]]

 [[128  93  44]
  [139  67  44]
  [150  67  46]
  ...
  [159  87  58]
  [175  96  56]
  [175  99  54]]

 [[128  68  36]
  [139  68  36]
  [150  67  43]
  ...
  [159 124  62]
  [175  93  54]
  [175  96  46]]]