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2015-05-02 05:56:34 -0500 commented question Matching shapes (especially characters) based on their histograms

Can I analyse somehow the hu moments in order to determine image orientation and compare only images oriented in the same direction?

2015-05-02 05:43:02 -0500 commented question Matching shapes (especially characters) based on their histograms

thanks, but now that I know it, unfortunately it seems to me that this solution with cv::reduce is not reposition invariant. My program needs to match two shapes if they are a bit distorted and repositioned :( I think I will need to stick to the matchShapes. I would be grateful if you could tell me what arguments would be best in your opinion, now I am calling the function this way: cv2.matchShapes(contours1d, contours1d2, 2, 0) after finding contours of the characters.

2015-05-02 05:12:58 -0500 commented question Matching shapes (especially characters) based on their histograms

ok, I am still not that fluent in image processing, I presumed that calcHist would return me histograms similar to the ones presented : here but in that thread I can't seem to find a way of determining the dissimilarity measure between images. That's why I thought of calcHist and compareHist. How can I compare the outputs of `reduce' to find that measure?

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2015-05-02 04:36:54 -0500 commented question Matching shapes with Hausdorff and Shape Context distance

Hmm, now it looks like a definite bug. I thought I passed some wrong arguments to the computeDistance function but I see I did it the same way as you.

2015-05-02 04:33:26 -0500 asked a question Matching shapes (especially characters) based on their histograms

I would like to find a similarity measure between two images showing characters taking into account their histograms. An image example may contain just an individual letter or it could contain several characters and look like this:

image description.

Can anyone please guide me through how to use calcHist function in order to feed its output to compareHist function and find a similarity measure between such images. The important point is that the characters may not look the same and may be a little bit distorted while they still remain similar.

I tried out outer approaches such as matchShapes but because they are quite often rotation invariant, they sometimes do not provide satisfactory results and letter p is then similar to letter d.

2015-05-01 05:17:41 -0500 commented question Matching shapes with Hausdorff and Shape Context distance

I would like to highlight that I am using the Python version of OpenCV 3.0. I have just checked that in the C++ version everything seems to be working fine. Has anyone stumbled upon such a problem?

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2015-04-30 15:38:57 -0500 asked a question Matching shapes with Hausdorff and Shape Context distance

I want to compute a distance between two shapes using the Hausdorff distance or shape context distance measure available in OpenCV 3.0. The shapes are simple white shapes on a black background.

In order to find the distance between two shapes, I find contours of each shape and then pass the contours two the following functions: ShapeDistanceExtractor::computeDistance(contours1, countours2) and HausdorffDistanceExtractor::computeDistance(contours1, countours2).

Could anyone please explain to me, why during the comparison the ShapeDistanceExtractor always returns 0.0, whereas the second method gives me different results depending on the position of a character on the image?