为什么Pytesseract无法识别黑色的纯白色文本？

Question

I have a lot of images like below that I need to use pytesseract with to grab the white text:

I use the following code, but the results are not impressive:

import pytesseract
from PIL import Image
pytesseract.pytesseract.tesseract_cmd = 'C:/Program Files (x86)/Tesseract-OCR/tesseract'
im = Image.open('topLine.png')
print pytesseract.image_to_string(im)

Results:

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RJ |G | B (mmm @

So I thought the reason was non-text inside the image. I cropped the part of the image with the most important text to me and ran the same code against it:

However, all I got was blank. Pytesseract didn't find any text at all. What am I doing wrong?

Answer 1

To answer your original question is I believe their training dataset is only on black text white background so its not surprising the machine learning algorithm wont pick up the inverse. Now for the solution, if the black box with white text is in a specific spot in the images every time, i would just crop it out, inverse it, then put it back in the same spot. otherwise you can use erode/dilate tools with a customized kernel to find these black boxes and essentially create a masking over that part of the image. Using this masking you can say hey python, here is a black box with white text inverse it. In my experience, pytesseract has always needed at least some image processing (if not alot) to get good output, but even with the most screwed up images i have been able to get accuracies above 93%.