Signature recognition algorithms?

Question

Algorithms

The crux of the matter is this. we have a resistive touch screen which is a field for entering a signature and conditionally the original signature, and here and there we have not only a picture as a result, but also the order of writing it ...
Actually, the subject needs an algorithm or a link to where you can read about it ... and how can be less voracious, since it will spin on the microcontroller.

Answer 1

You can borrow the approach from gesture recognizers (for example, All-in-one Gestures ).
As the gesture (signature) is drawn, the program determines the direction of mouse (stylus) movement, “rounding” it to one of the four main directions: left, right, up, down. The repetition of the same direction is ignored (that is, "LLLLL" is considered one "L") - this eliminates the difference in the scale of gestures.
As a result, even such a complex gesture as a signature can be represented as a relatively short sequence a la ULDRUDRULDR (the @ symbol in my version), where each character takes only two bits. Thus, a dozen bytes are more than enough to store even a complex signature.

Direction recognition is easily done on the fly: when the stylus has moved N pixels from the starting point, we compare Δx with Δy, and their signs; if the received direction differs from the previous one, we add it to the chain of recognized ones and goto 1. Small hand tremors can be filtered out by setting N > 1.
Just before implementing it in hardware, check the accuracy of recognition on a computer, at least in the same browser. Just in case :)

Answer 2

Another interesting question is the legal force of such a signature.

Answer 3

The new Federal Law on Electronic Signature gives such a broad permissive interpretation that it is breathtaking.
Just the last name and first name at the end of the e-mail and then can be recognized as an analogue of a handwritten signature (HSA), if the parties so desire. Well, at least most people have the common sense not to do it.