If the shape of maker in the input frame is quite apparent you can use the below solution.
In the first you have to prepare the template image by the following preprocessing steps:
1-Use the sobel derivatives then opening the result image.
2-In this state you can compute the region of blob(ROI) then expand this region.
3-Crop the ROI then resize it to specific size .
4-Apply the threshold on image then compute center of mass .
5-Apply the canny algorithm over the image.
6-By cvLogPolar & center of mass point transfer the image to polar space.
In the enrolment step for all of the markers that you have to recognize them applay the above preprocessing step & save each template in database.
In the test step Apply the preprocssing on input frame then use cvMatchTemplate for match of test sample by all of template images in database.
Each template that have the greatest peek is the answer of problem.