How to improve accuracy of OpenCV template matching

Question

I tried using MatchTemplate() to match numbers in image. For example, the numbers are [0985-977-735] in image. And got the results as following:(number, location) [(0, 1), (3, 103), (5, 33), (5, 116), (7, 62), (7, 73), (7, 85), (8, 21), (9, 11), (9, 53)]

But in most situations, the accuracy is very low.

[0983-945-180]: [(0, 113), (1, 93), (3, 31), (4, 62), (5, 74), (8, 103), (9, 11), (9, 53)] the first zero and eight can't be recognized.

[0932-509-607] [(0, 103), (2, 31), (3, 21), (5, 54), (6, 92), (7, 113), (9, 72)] the first, second zero and first nine can't be recognized.

[0911-873-752] [(0, 1), (1, 22), (1, 33), (2, 113), (3, 72), (5, 105), (7, 92), (8, 52), (9, 11)] the first seven can't be recognized.

part of the code as following:

import cv
for i in range(10):
    template_im = cv.LoadImage(template_file, cv.CV_LOAD_IMAGE_GRAYSCALE)
    width = original_im.width - template_im.width + 1
    height = original_im.height - template_im.height +1
    result_image = cv.CreateImage((width, height), cv.IPL_DEPTH_32F, 1)
    cv.Zero(result_image)
    cv.MatchTemplate(original_im, template_im, result_image, cv.CV_TM_CCOEFF_NORMED)
    (_, R, _, max_loc) = cv.MinMaxLoc(result_image)

    if R < 0.90:
        pass
    else:
        phone_number_location.append((i, max_loc[0]))
        ...
        ...

If you are looking for a digit OCR, you can see a simple implementation here using OpenCV-Python.http://stackoverflow.com/questions/9413216/simple-digit-recognition-ocr-in-opencv-python/9620295#9620295 — Abid Rahman K, Apr 23 '12 at 17:17
possible duplicate of [digit recogntion using OpenCV on android](http://stackoverflow.com/questions/10107258/digit-recogntion-using-opencv-on-android) — karlphillip, Apr 23 '12 at 17:50

score 0 · Accepted Answer · answered Apr 23 '12 at 17:33

You may like to use SimpleCV for this. It is written in python. Most of the things you require are in it. I wrote a basic image stitching app in just 15 lines of code. Hope this helps. Use the code in github because template matching is new in SimpleCV. Hope this helps.

How to improve accuracy of OpenCV template matching

1 Answers1