Patent ID: 6801664
Filing Date: 2004-10-05
Classification: H04N

Abstract:
A method of image coding for coding a continuous-tone image into a binary coded image; said method including:a first halftoning converting step for producing first bi-level image data by quantizing continuous-tone image data of whole pixels in a section including a target pixel and pixels surrounding the target pixel; and a predicting step for providing second bi-level image data by predicting data at the target pixel based on data at the surrounding pixels; a predictive coding step for determining respective differences between the first and second bi-level image data for the whole pixels in the section; and a threshold changing step for changing a threshold value used at said first halftoning converting step in responsive to the determined respective differences; wherein the first bi-level image is produced in said first halftoning converting step so that a prediction in said predicting step becomes strong.