Digital, high contrast displays are getting wide-spread in public transport, public areas and offices due to their ability to update their contents. Finding and reading them is of great importance when navigating, which is one of the most important functions in the formerly proposed Bionic Eyeglass, a mobile navigation guide for blind and visually impaired people. In this paper we present a novel algorithm for color cellular visual microprocessors to localize displays in image flows and an enhanced algorithm to recognize numbers on them. The cellular wave algorithms for sign localization combine color information with spatial-temporal logic. Imminent properties of color displays as well as device specific details were considered during algorithmic design.