compare a marker in an image with a database

hi,

i want to compare an image (containing the desired marker) with a database. to be more specific, i have a brunch of markers each with different pattern. i will save all of them in a file. then i will capture a random image that has a marker in that image. the job now is to identify that particular marker and display a certain message.

i really appreciate your reply. thank you for helping me out.

[Walter Roberson]

The markers: are they of known size and known orientation? Or could they appear in different sizes and different angles? In the picture, could they be partly obscured?

[Image Analyst]

Can you upload a picture? http://www.mathworks.com/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers So all the markers are in a file, a single image file - not one marker per file? That makes it kind of hard to check your captured image against all the markers individually. We might have to split them up into multiple files with one marker per file.

[genesis]

the markers are of the same size and with known orientation. yes they could be different scales and angles in the picture. how can i compare the captured marker with a set of other markers in a database? if SIFT possible in this case?