Template Matching Subpixel Accuracy
I use template matching to detect a specific pattern in image.The shift determined is very shaky. Currently I apply it to R,G,B channel separately and average the result to obtain float values.Please, suggest how to obtain subpixel accuracy. I was planning to resize the image and then return the data in original scale, please suggest any other better method.
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I use the code mentioned on Opencv site "http://docs.opencv.org/2.4/doc/tutorials/imgproc/histograms/template_matching/template_matching.html"
I believe the underlying issue is that minMaxLoc has only pixel accuracy. You could try out a subpixel-accurate patch http://www.longrange.net/Temp/CV_SubPix.cpp from the discussion here: http://answers.opencv.org/question/29665/getting-subpixel-with-matchtemplate/ .
As a quick and dirty experiment if a sub-pixel accurate minMaxLoc would resolve your issue, you can scale up the template matching result image (by a factor of 4, for instance) with cubic interpolation INTER_CUBIC http://docs.opencv.org/2.4/modules/imgproc/doc/geometric_transformations.html#resize and apply minMaxLoc on it. (Contrary to linear interpolation, cubic interpolation does move maxima.)
Apart from this, you can always apply Gaussian blur to both input images and template matching results to reduce high-frequency noise and suppress local maxima.
I would first try out the quick experiment. If it helps, you can integrate the minMaxLogSubPix implementation, but that will take longer.
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