Digital binarization circuit for conversion of image data

Abstract From the Canadian patent

A digital binarization circuit for image data includes a background level detecting circuit which uses a video signal as a reference input for determining the background level of an image represented by the video signal, and outputs the background level as a first address signal. A character level detecting circuit compares the video signal with a character level in a load decision comparator and loads the video signal as a character level when the signal is less than the reference level and outputs the character level as a second address signal. A memory circuit outputs a threshold value stored at an address designated by the first and second address signals to a comparator. The optimum …