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pythonopencvocr

How do I crop multiple images from one picture based on the background color?

So I have an image and I want to cut it up into multiple images to feed into OCR to read.

image example

I only want the messages with the white bubbles and exclude anything with the grey bubbles. I can't figure out how to make a loop to separate each white bubble.

import numpy as np
from PIL import ImageGrab, Image, ImageFilter

img = Image.open('test1.png').convert('RGB')
na = np.array(img)
orig = na.copy()
img = img.filter(ImageFilter.MedianFilter(3))

whiteY, whiteX = np.where(np.all(na==[255,255,255],axis=2))
top, bottom = whiteY[1], whiteY[-1]
left, right = whiteX[1], whiteX[-1]
Solution

  • You could try using the opencv threshold function, followed by the findContours function. This will, if you threshold the image correctly, give you the 'borders' of the bubbles above. Using that, you could then crop out each text bubble.

    Here's a simple example of contours being used: https://www.geeksforgeeks.org/find-and-draw-contours-using-opencv-python/

    Otherwise if you'd like to understand better how the opencv functions I mentioned or those that are used in the article above, have a look at the opencv documentation.