Tesseract - digit regonition with many errors

Question

I want to be able to recognize digits from images. So I have been playing around with tesseract and python. I looked into how to prepare the image and tried running tesseract on it and I must say I am pretty disappointed by how badly my digits are recognized. I have tried to prepare my images with OpenCV and thought I did a pretty good job (see examples below) but tesseract has a lot of errors when trying to identify my images. Am I expecting too much here? But when I look at these example images I think that tesseract should easily be able to identify these digits without any problems. I am wondering if the accuracy is not there yet or if somehow my configuration is not optimal. Any help or direction would be gladly appreciated.

Things I tried to improve the digit recognition: (nothing seemed to improved the results significantly)

limit characters: config = "--psm 13 --oem 3 -c tessedit_char_whitelist=0123456789"
Upscale images
add a white border around the image to give the letters more space, as I have read that this improves the recognition process
Threshold image to only have black and white pixels

Examples:

Image 1:

Tesseract recognized: 72

Image 2:

Tesseract recognized: 0

EDIT: Image 3:

https://ibb.co/1qVtRYL

Tesseract recognized: 1723

I think textract doesn't work with images or am I wrong? I want to be able to recognize these digits from images. — Dynamicnotion

Ian Chu Ian Chu · Accepted Answer · 2021-02-27T17:36:50

I'm not sure what's going wrong for you. I downloaded those images and tesseract interprets them just fine for me. What version of tesseract are you using (I'm using 5.0)?

781429

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import pytesseract
import cv2
import numpy as np
from PIL import Image

# set path
pytesseract.pytesseract.tesseract_cmd = r'C:\\Users\\ichu\\AppData\\Local\\Programs\\Tesseract-OCR\\tesseract.exe';

# load images
first = cv2.imread("first_text.png");
second = cv2.imread("second_text.png");
images = [first, second];

# convert to pillow
pimgs = [];
for img in images:
    rgb = cv2.cvtColor(img, cv2.COLOR_BGR2RGB);
    pimgs.append(Image.fromarray(rgb));

# do text
for img in pimgs:
    text = pytesseract.image_to_string(img, config='--psm 10 --oem 3 -c tessedit_char_whitelist=0123456789');
    print(text[:-2]); # drops newline + end char

Tesseract - digit regonition with many errors

1 Answers