I am developing a GUI using TKinter that allows users to interactively set parameters that are used for processing some images. The GUI displays the image that is being analyzed so that users can see how changing the parameters changes the result of the image processing. After realizing that the method I am using to process images does not perform well, I decided to create another GUI that I can use to debug the method. This debugging GUI will display two images – the original one being processed, and a binary mask that will be used to isolate features on the original. After developing this GUI, I noticed that when displaying the images, there is now a strange white box in the center of the image that was not there on the original one.

Here are examples to illustrate the issue:

original code for displaying image on a TK label:

def display_image(img):
    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
    img = Image.fromarray(img)
    img = ImageTk.PhotoImage(image=img)
    photo_label.imgtk = img
    photo_label.config(image=img)

resulting image (cropped only to show area near the center where the issue is occurring):
how it should look

code for displaying image on the debugging GUI that allows for selecting whether I am showing an image on the original photo label or the label for the binary mask:

def display_image(img, window = "photo"):
    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
    img = Image.fromarray(img)
    img = ImageTk.PhotoImage(image=img)
    if window == "photo":
        photo_label.imgtk = img
        photo_label.config(image=img)
    elif window == "mask":
        mask_label.imgtk = img
        mask_label.config(image=img)

resulting image with issue:

image with new white rectangle on the issue

Does anyone know why this may be happening and if there is anything that I can do to get rid of it?