Patent ID: 8254451

Claim:
An image coding apparatus which performs field-coding on input image data, the image coding apparatus comprising: a reference index assignment unit configured to assign reference indices to plural reference pictures which are referred to by a current picture to be coded included in the input image data, each of the reference indices having a different value and being assigned to a corresponding one of the plural reference pictures; and an image coding unit configured to perform the field-coding on the current picture to be coded, by referring to the reference pictures indicated by the reference indices assigned by the reference index assignment unit, and to code the reference indices, wherein the reference index assignment unit is configured to assign, to a reference picture having a parity opposite to a parity of the current picture to be coded, a reference index having a value smaller than a value of a reference index to be assigned to a reference picture having a same parity as the parity of the current picture to be coded, when reference indices are assigned to, among the plural reference pictures, two reference pictures which are two fields belonging to a same frame, one of which being a top field and the other of which being a bottom field.