1. A computer-implemented method for matching an image-form textual string in an image to a regular expression, comprising: constructing a representation of said regular expression; generating a candidate string of characters from said image-form textual string; ascertaining whether there exists a match between said image-form textual string and said regular expression, said match is deemed achieved if a probability value associated with said match is above a predetermined matching threshold; and said representation has at least a first state representing uncertainty whether said image-form textual string matches said regular expression and a success state representing a successful match between said image-form textual string and said regular expression and wherein said generating said candidate string of characters including a plurality of candidate characters occupying a plurality of character positions, each candidate character of said plurality of candidate characters associated with a respective recognition probability and wherein said ascertaining includes applying said candidate string of characters character position-by-character position against said representation, whereby processing a candidate character of said candidate string results in a next state and a probability value, said match is deemed achieved when a given next state associated with a given candidate character of said plurality of characters computed during said applying is said success state of said representation and said probability value associated with said given next state is above said predetermined matching threshold.