BINARY FORM SIGNAL CODING/DECODING DEVICE

摘要

PROBLEM TO BE SOLVED: To further reduce a data amount to be sent and to enhance coding efficiency by comparing a predicted binary pixel value with an original pixel value and adaptively coding the count of binary pixels whose value is the same as the predicted value. SOLUTION: A context number calculation section 120 calculates a context number and the probability corresponding to a current pixel. A state decision section 130 compares the present probability with a predetermined threshold to classify a quality state of the current pixel and compares the present probability with, e.g. a half a highest probability to determine a predicted pixel value. A comparison section 140 compares the predicted pixel value with a current pixel value and assigns a mapping value denoting a background pixel to the current pixel value identical to the predicted pixel value. A rearrangement section 150 rearranges the mapping values to classify quality a state of the current pixel and counts the number of background pixels. A probability set decision section 160 uses the count of the background pixels to determine an optimum probability set. An adaptive arithmetic coding section 170 codes data by an arithmetic coding technology based on the optimum probability set.