CODEWITHSUNDEEP
pythonpython-3.xocrtesseract
jodayme
jodayme

Reputation: 73

How to read black text on black background image through tesseract OCR?

I have black text on black background image and I want to read it through OCR. Unfortunately, OCR can not read it perfectly. The image look like this. enter image description here I want to convert RGBA value that less than (90, 90, 90, 255) to (255, 255, 255, 255) so it turn B & W. What's the code to convert it?

Upvotes: 5

Views: 2149

Answers (2)

Bruno Aquino
Bruno Aquino

Reputation: 103

You can transform your gray pixels in white pixels with a simple transformation. If you don't want to use open cv and your image is one channel (gray scale) numpy array:

threshold = 60 # try something between 30 and 150
vect_func = np.vectorize(lambda x: 0 if x == threshold else 255)
black_white_img = vect_func(gray_scale_image)

Upvotes: 0

Jose Angel Sanchez
Jose Angel Sanchez

Reputation: 764

What you need to do is make the whole image black and white before letting tesseract do its job.

Read image

import cv2
im_gray = cv2.imread('your_image_here', cv2.IMREAD_GRAYSCALE)

Make it grayscale 

(thresh, im_bw) = cv2.threshold(im_gray, 128, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)

"which determines the threshold automatically from the image using Otsu's method, or if you already know the threshold you can use:"

thresh = 127
im_bw = cv2.threshold(im_gray, thresh, 255, cv2.THRESH_BINARY)[1]

Write to disk

cv2.imwrite('bw_image.png', im_bw)

Taken from here

Upvotes: 6

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