Image binarization method and device for converting a grayscale image into a black and white binary image are provided. The grayscale image is divided into sub-images dynamically created from pixel to pixel containing a given pixel as well as neighboring pixels. A threshold for each pixel is determined based on the color values of all the pixels in the sub-image. Therefore, at a certain color value, this given pixel is converted to white and at another color value the pixel is converted black. The foregoing is effectuated pixel by pixel in a dynamic fashion evaluating each pixel relative to its neighboring pixels in order to produce a binary image.