[Python] Performing OCR of Seven Segment Display Multimeter

Firstly, I am very very new to these things, and I have come this far with the help of ChatGPT.

We recorded some videos of two multimeters that have seven-segment displays. I want to OCR them to use later to sketch graphs. I am using a config file that has names and xy-coordinates. My code works, but when I see the cropped pictures, I think they are very readable. However, OCR doesn't read most of them, and the ones it reads are all wrong. How can I achieve it to read all that correctly?

Original image:



Resulting image:



My code:

# -- coding: utf-8 --
import cv2 import pytesseract

pytesseract.pytesseract.tesseract_cmd = r'C:\Program Files\Tesseract-OCR\tesseract.exe'

with open('config.txt', 'r') as f: lines = f.readlines()
for line in lines: parts = line.strip().split()
if len(parts) != 9:
continue

video_name = parts[0]
volt_y1, volt_y2, volt_x1, volt_x2 = map(int, parts[1:5])
curr_y1, curr_y2, curr_x1, curr_x2 = map(int, parts[5:9])

cap = cv2.VideoCapture(video_name)

fps = cap.get(cv2.CAP_PROP_FPS)
frame_interval = int(fps * 0.5)

frame_count = 0

while True:
ret, frame = cap.read()
if not ret:
break

if frame_count % frame_interval == 0:
volt_crop = frame[volt_y1:volt_y2, volt_x1:volt_x2]
curr_crop = frame[curr_y1:curr_y2, curr_x1:curr_x2]


volt_crop_gray = cv2.cvtColor(volt_crop, cv2.COLOR_BGR2GRAY)
volt_crop_thresh = cv2.threshold(volt_crop_gray, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)[1]

curr_crop_gray = cv2.cvtColor(curr_crop, cv2.COLOR_BGR2GRAY)
curr_crop_thresh = cv2.threshold(curr_crop_gray, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)[1]

# OCR
volt_text = pytesseract.image_to_string(volt_crop_thresh, config='--psm 7', lang='7seg')
curr_text = pytesseract.image_to_string(curr_crop_thresh, config='--psm 7', lang='7seg')

cv2.putText(volt_crop_thresh, f'Volt: {volt_text.strip()}', (10, 30), cv2.FONT_HERSHEY_SIMPLEX, 0.8, (0, 0, 255), 2) # Kırmızı
cv2.putText(curr_crop_thresh, f'Current: {curr_text.strip()}', (10, 30), cv2.FONT_HERSHEY_SIMPLEX, 0.8, (0, 255, 0), 2) # Yeşil

cv2.imshow('Voltmetre Crop', volt_crop_thresh)
cv2.imshow('Ampermetre Crop', curr_crop_thresh)

if cv2.waitKey(1) & 0xFF == 27:
break

frame_count += 1

cap.release()
cv2.destroyAllWindows() `

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