Enhancement of video images by selective introduction of gray-scale pels

In a system for receiving and storing binary data representative of pels in a previously captured image wherein the binary data is stored in a memory array, arranged in logical rows and logical columns, at a density of one bit per pel, a method of assigning gray scale values to certain pels to enhance the visual quality of the image when displayed on a gray scale display device, said method characterized by the steps of:

• examining the stored binary data on a pel by pel basis along successive pel lines to identify unit steps in binary pel values in a direction transverse to the direction of the successive lines, each identified unit step being adjacent a pel arbitrarily defined as occurring at an intersection of row J and column I in a display area;
• examining the binary data beginning at column I+1 and continuing to the right until a display boundary is encountered or a change in binary data is found in row J or in one of rows J-1 and J+1 to derive a pel distance RD;
• examining the binary data beginning at column I and continuing to the left until a display boundary is encountered or a change in binary data is found in row J or one of rows J-1 and J+1 to derive a pel distance LD;
• modifying the stored data representing pels to the right of the unit step by assigning gray scale values as a function of the derived distance RD;
• modifying the stored data representing pels to the right of the unit step by assigning gray scale values as a function of the derived distance RD;
• modifying the stored data representing pels to the left of the unit step by assigning gray scale values as a function of the derived distance LD;
• assigning fixed gray scale values to any pels remaining unchanged following the modifying steps to fix upper and lower limits on gray scale pel values;
• and
• generating the displayed image in accordance with the assigned gray scale pel values.

A system for enhancing the visual quality of a gray scale image produced by a gray scale display device where the image is derived from data stored at a density of one bit per pel, said system including:

• means for examining the stored data to locate unit steps in binary pel values;
• means for assigning gray scale values to pels on opposite sides of each unit step to create a string of gradually changing pel values extending through each identified unit step;
• means for assigning fixed gray scale values to any pels not already modified to establish limiting black/white pel values;
• and
• means for generating the displayed image in accordance with the assigned gray scale pel values.