A method for encoding a symbol such as a barcode with a finder of a known pattern, comprises steps of determining a potential point on the finder edge and tracing and verifying a path representing the finder edge by checking the color of each point on the path against a threshold. The threshold is preferably reevaluated at least every several pixel movements along the path. The method may decode the barcode directly from the gray image displayed on a LCD screen without a need of a whole characterized image.
