An image coding method for performing compression-coding on image data includes: binarizing a signal to be coded of the image data, to generate a binary signal; determining a low-order context which is a context associated with a type of the signal to be coded, and a high-order context that is common to the low-order context and a context associated with another type; calculating coding probability information to be used in arithmetic coding of the binary signal, using (i) high-order probability information corresponding to the determined high-order context and (ii) low-order probability information corresponding to the determined low-order context; performing the arithmetic coding on the binary signal using the coding probability information; and updating the high-order probability information and the low-order probability information based on the binary signal.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An image coding method for performing compression-coding on pixel image data, said image coding method comprising: binarizing a signal to be coded of the pixel image data, to generate a binary signal; determining a first low-order context, wherein the first low-order context is associated with a type of the signal to be coded; determining a first high-order context that is common to the first low-order context and at least one second low-order context which is other than the first low-order context, wherein the second low-order context is associated with another type of a signal; calculating coding probability information to be used in arithmetic coding of the binary signal, using first high-order probability information corresponding to the determined first high-order context and first low-order probability information corresponding to the determined first low-order context; performing the arithmetic coding on the binary signal using the calculated coding probability information; and updating the first high-order probability information and the first low-order probability information based on the binary signal.
2. The image coding method according to claim 1 , further comprising obtaining type information indicating the type of the signal to be coded, wherein in said determining, the first high-order probability information and the first low-order probability information are determined by referring, based on the type information, to a table in which the following are associated with one another: a plurality of types; a high-order context common to the types; and low-order contexts each associated with a corresponding one of the types.
3. The image coding method according to claim 1 , wherein in said calculating, the coding probability information is calculated by weighted-summation of the first high-order probability information and the first low-order probability information.
4. The image coding method according to claim 1 , further comprising obtaining a control signal to be used in the calculation of the coding probability information, wherein in said calculating, the coding probability information is calculated using the first high-order probability information, the first low-order probability information, and the control signal.
5. The image coding method according to claim 4 , further comprising coding the control signal.
6. The image coding method according to claim 1 , wherein the first high-order probability information and the first low-order probability information is an index indicating a value of a symbol occurrence probability.
7. The image coding method according to claim 1 , wherein the first high-order probability information and the first low-order probability information is a value of a symbol occurrence probability.
8. An image coding apparatus that performs compression-coding on pixel image data, said image coding apparatus comprising: a hardware processor; and a non-transitory memory storing thereon a program which is executed by the hardware processor and causes the image coding apparatus to: binarize a signal to be coded of the pixel image data, to generate a binary signal; determine a first low-order context, wherein the first low-order context is associated with a type of the signal to be coded; determine a first high-order context that is common to the first low-order context and at least one second low-order context which is other than the first low-order context, wherein the second low-order context is associated with another type of a signal associated with another type; calculate coding probability information to be used in arithmetic coding of the binary signal, using first high-order probability information corresponding to the determined first high-order context and first low-order probability information corresponding to the determined first low-order context; perform the arithmetic coding on the binary signal using the calculated coding probability information; and update the first high-order probability information and the first low-order probability information based on the binary signal.
9. The image coding apparatus according to claim 8 , wherein said image coding apparatus is configured as an integrated circuit.
10. A non-transitory computer-readable recording medium on which a program is stored, the program causing a computer to execute the image coding method according to claim 1 .
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October 28, 2014
February 23, 2016
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