binary image subtration

i am trying to subtract two binary images (two signatures of same person) i tried using imsubtract(), xor(), bitxor() all are giving me a image with black background and white signature. plz help

[Walter Roberson]

You have not indicated what your difficulty is.

Give us the "truth table" and we'll tell you how to implement it.

First picture is B, second picture is W, result should be ... ?

First picture is B, second picture is B, result should be ... ?

etc.

[Amit Vaswani]

picture A binary image of a signature (in database)

picture B binary image of same person's signature.

result should complete black image or few white dots.

[Walter Roberson]

Consider pixel by pixel. You have black in first, white in second, and you want out what? You have black in first and black in second pixel and you want out what? And so on. Four input combination, 4 outputs. If you can create that pixel-by-pixel "subtraction" table, then we can tell you what the formula would be.

Answer 1

[Image Analyst]

That will be an unsuccessful method to compare signatures, if that's what you're trying to do. You'd be better off seeing what kind of methods other people have used successfully here: http://iris.usc.edu/Vision-Notes/bibliography/contentschar.html#OCR,%20Document%20Analysis%20and%20Character%20Recognition%20Systems

[Amit Vaswani]

thanks for reply. :)

i am new to matlab,can you suggest me a easy offline signature recognition method.

[Image Analyst]

I think I did that already. Did you see the link I gave? I personally haven't tried all of those dozens of algorithms so other than pointing you to them I have nothing else to suggest or recommend.