Picture coding method, picture decoding method, picture coding apparatus, picture decoding apparatus
The picture coding method according to the present invention is a picture coding method for coding a picture on a block-by-block basis through orthogonal transformation and quantization, and coding a quantization matrix that is used to derive quantization steps for frequencies of orthogonal transformation coefficients, the method comprising: calculating a difference value between each of frequency components included in the quantization matrix and a predetermined value corresponding to said each of the frequency components; and coding the difference value into a variable length code, wherein a code length of the variable length code is shorter as the difference value is smaller, or equal to a code length of a neighboring difference value of said difference value.
1. A method for decoding a coded quantization matrix with a picture decoding apparatus, said method comprising:
decoding a coded stream into a difference value ranging from −128 to +127;
adding together a value of an (I−1)th component in the quantization matrix, the difference value, and 256; and
calculating a remainder by dividing the result of said adding by 2 raised to 8-th power to obtain the value of an I-th component.
2. The method for decoding a coded quantization matrix according to claim 1 , wherein said decoding of the coded stream is finished when the obtained value of the I-th component is zero.
3. The method for decoding a coded quantization matrix according to claim 1 , wherein the result of said adding is a positive value.
4. The method for decoding a coded quantization matrix according to claim 1 wherein said decoding of the coded stream includes:
counting the number N of subsequent zeros from the beginning of the coded stream;
reading one bit of value one subsequent to the N number of zeros and N-bits subsequent to the one bit of value one; and
obtaining, as to the different value, a value corresponding to the N-bits.
5. An apparatus for decoding a coded quantization matrix, said apparatus comprising:
a decoding unit operable to decode a coded stream into a difference value ranging from −128 to +127;
an addition unit operable to add together a value of an (I−1)th component in the quantization matrix, the difference value, and 256; and
a calculation unit operable to calculate a remainder by dividing a result of said adding by 2 raised to 8-th power to obtain the value of the I-th component.
6. An integrated circuit for use in a decoding apparatus which decodes a coded quantization matrix, said integrated circuit comprising:
an operation unit operable to:
decode a coded stream into a difference value ranging from −128 to +127;
add together a value of an (I−1)th component in the quantization matrix, the difference value, and 256; and
calculate a remainder by dividing a result of said adding by 2 raised to 8-th power to obtain the value of an I-th component which is an integer equal to or smaller than 255.
7. A non-transitory computer readable recording medium for storing a program, which is used in a computer, for decoding a moving picture, said program causing a computer to execute steps for decoding a coded quantization matrix, wherein said steps include:
decoding a coded stream into a difference value ranging from −128 to +127;
adding together a value of an (I−1) the component in the quantization matrix, the difference value, and 256; and
calculating a remainder by diving a result of said adding by 2 raised to 8-th power to obtain the value of an I-th component which is an integer equal to or smaller than 255.