Arithmetic encoding device, arithmetic decoding device, arithmetic encoding method, and arithmetic decoding method

Abstract

The amount of processing is reduced with high coding efficiency maintained. There is provided an arithmetic decoding device including syntax decoding means for decoding each of at least a first syntax element and a second syntax element indicating a transform coefficient using arithmetic decoding with a context or arithmetic decoding without a context. The syntax decoding means performs decoding that at least includes not decoding the first syntax element and decoding the second syntax element using the arithmetic decoding without a context, and decoding the first syntax element using the arithmetic decoding with a context and decoding the second syntax element using the arithmetic decoding without a context.

1 . (canceled) 
     
     
         2 : An arithmetic encoding device for arithmetically encoding a transform coefficient obtained by performing a frequency transform on a target image for each unit region, comprising:
 syntax encoding circuitry that encodes a first syntax element and a second syntax element that indicate the transform coefficient; wherein   the first syntax element is a syntax element relating to whether or not the absolute value of the transform coefficient is larger than a predetermined value and is encoded by using arithmetic encoding with a context,   the second syntax element is a syntax element relating to a value obtained by subtracting a predetermined value from the absolute value of the transform coefficient and is encoded without a context, and   the syntax encoding circuitry performs encoding that at least includes both:   (i) not encoding the first syntax element and encoding the second syntax element, and   (ii) encoding the first syntax element and the second syntax element.   
     
     
         3 : An arithmetic decoding device for arithmetically decoding coded data of a transform coefficient obtained by performing a frequency transform on a target image for each unit region, comprising:
 syntax decoding circuitry that decodes a first syntax element and a second syntax element that indicate the transform coefficient; wherein   the first syntax element is a syntax element relating to whether or not the absolute value of the transform coefficient is larger than a predetermined value and is decoded by using arithmetic decoding with a context,   the second syntax element is a syntax element relating to a value obtained by subtracting a predetermined value from the absolute value of the transform coefficient and is decoded without a context, and   the syntax decoding circuitry performs decoding that at least includes both:   (i) not decoding the first syntax element and decoding the second syntax element, and   (ii) decoding the first syntax element and the second syntax element.   
     
     
         4 : An arithmetic encoding method for arithmetically encoding a transform coefficient obtained by performing a frequency transform on a target image for each unit region, comprising:
 syntax encoding step that encodes a first syntax element and a second syntax element that indicate the transform coefficient; wherein   the first syntax element is a syntax element relating to whether or not the absolute value of the transform coefficient is larger than a predetermined value and is encoded by using arithmetic encoding with a context,   the second syntax element is a syntax element relating to a value obtained by subtracting a predetermined value from the absolute value of the transform coefficient and is encoded without a context, and   the syntax encoding step performs encoding that at least includes both:   (i) not encoding the first syntax element and encoding the second syntax element, and   (ii) encoding the first syntax element and the second syntax element.   
     
     
         5 : An arithmetic decoding method for arithmetically decoding coded data of a transform coefficient obtained by performing a frequency transform on a target image for each unit region, comprising:
 syntax decoding step that decodes a first syntax element and a second syntax element that indicate the transform coefficient; wherein   the first syntax element is a syntax element relating to whether or not the absolute value of the transform coefficient is larger than a predetermined value and is decoded by using arithmetic decoding with a context,   the second syntax element is a syntax element relating to a value obtained by subtracting a predetermined value from the absolute value of the transform coefficient and is decoded without a context, and   the syntax decoding step performs decoding that at least includes both:   (i) not decoding the first syntax element and decoding the second syntax element, and   (ii) decoding the first syntax element and the second syntax element.