Extract similar area of two images

Question

I wonder that extracting similar area of images is possible. if it is possible,i am going to find insigne of copmany which created it.

There are two images below. The red rectangles in the images are that i try to find area. The program is going to find similar area comparing images. I tried to find it using opencv,but i couldn't do it.

enter image description here

You could just look through each pixel and check if they're the same. — john01dav, May 06 '14 at 09:10
it wouldn't be same position. And sometimes I need to compare more than 1000 images. I think, I need more effective way to do it. — RockOnGom, May 06 '14 at 09:18

score 3 · Accepted Answer · edited May 23 '17 at 12:15

3

First thing in mind:

Convert images to grayscale
Divide image into small areas (patches)
Each patch should be labelled as 1 if entropy of image is high and 0 if low (to discard patches without letters)
For two images, compare all patches across images based on:
- Histogram on sobel image (Bhattacharya distance is normalized)
- Correlation (Minmax normalization)
- Advanced descriptors (like SIFT) (L2 normalization)
Min distance wins.

You can narrow down the '1' patches with a text detector (Algorithm to detect presence of text on image).

edited May 23 '17 at 12:15

Community

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answered May 06 '14 at 09:59

LovaBill

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I don't agree with (3), as the entropy might be still high if it's a natural image. I'd start with text detection first, which gives you the bounding boxes of the text parts, and therefore the image patches, really fast and without fixing the size of the patch beforehand. Moreover, SIFT or SURF won't work well with such small patches, I'd go for MPEG-7 Edge Histograms, PHOG or other advanced texture descriptors. – Mathias May 06 '14 at 14:37

Extract similar area of two images

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