I am interested in extracting numbers from standardized videos (always HD resolution @ 1920×1080, 30 FPS) I have. Numbers always appear in fixed sections of the screen and are never missing.
My approach would be to:
- Save video in frame by frame PNGs
- Load a single PNG frame
- Select the areas of interest (there are a four sections I want to
extract numbers from; each section might need their own image manipulation; always in the exact same pixel range) - Extract numbers using Python and Tesseract-OCR
- Store values in data frame
Examples of two of the sections are:
I have installed Python (I’m an R user) and tesseract and can run the Tesseract examples well (i.e. I have confirmed my setup works).
However, when I run the following commands on the top image [247] Tesseract is not able to extract the number, while you’d think it’s easy to extract as the text is very clear.
from PIL import Image import pytesseract import os import cv2 import argparse img = cv2.imread("C:/Users/Luc/Videos/Monza GR4 1.56.156/frames/frame1060_speed.png") cv2.imshow("RAW", img) cv2.waitKeyEx(0) cv2.destroyWindow() imgRGB = cv2.cvtColor(img, cv2.COLOR_BGR2RGB) cv2.imshow("RBG", imgRGB) cv2.waitKeyEx(0) cv2.destroyWindow() imgBW2WB = cv2.bitwise_not(imgRGB) cv2.imshow("White black swapped", imgBW2WB) cv2.waitKeyEx(0) cv2.destroyWindow() (thresh, blackAndWhiteImage) = cv2.threshold(imgBW2WB, 127, 255, cv2.THRESH_BINARY) cv2.imshow("Remove some noise", blackAndWhiteImage) cv2.waitKeyEx(0) cv2.destroyWindow() pytesseract.image_to_string(blackAndWhiteImage, config='--psm 10 --oem 3 -c tessedit_char_whitelist=0123456789')
The output is:
pytesseract.image_to_string(blackAndWhiteImage, config='--psm 10 --oem 3 -c tessedit_char_whitelist=0123456789') Out[15]: '7nx0c'
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Answer
Please use this Python code accordingly:
import cv2 from pytesseract import image_to_string import numpy as np def getText(filename): img = cv2.imread(filename) HSV_img = cv2.cvtColor(img,cv2.COLOR_BGR2HSV) h,s,v = cv2.split(HSV_img) v = cv2.GaussianBlur(v, (1,1), 0) thresh = cv2.threshold(v, 0, 255, cv2.THRESH_BINARY_INV + cv2.THRESH_OTSU)[1] cv2.imwrite('{}.png'.format(filename),thresh) kernel = cv2.getStructuringElement(cv2.MORPH_RECT, ksize=(1, 2)) thresh = cv2.dilate(thresh, kernel) txt = image_to_string(thresh, config="--psm 6 digits") return txt text = getText('WYOtF.png') print(text) text = getText('0Oqfr.png') print(text)
Here getText() function will take path of the png image file. After converting to HSV domain it will take the value component as v and then perform the Gaussian Blur before thresholding. You can try varying the kernel size of the dilate function accordingly to your images. The two images were given as input to the code above, and below is the output.
Output
247 0.10.694
Thresholding results
WYOtF.png
0Oqfr.png