Patent ID: 8335388

Claim:
An image coding apparatus which divides each of image data which is included in a corresponding one of fields into blocks each having a predetermined size, and performs predictive coding on each of the divided blocks, said image coding apparatus comprising: a parity judgment unit configured to judge whether a current field to be coded among the fields is a first field or a second field; a slice control unit configured to (i) divide the current field into an I-slice including intra coding blocks among the blocks and P-slices each including inter coding blocks among the blocks, and (ii) determine a position of a current I-slice in a current first field included in a predetermined number of first fields such that the current I-slice is sequentially shifted, on a per first field basis, from a first end of a starting first field to a second end of an ending first field in the predetermined number of first fields and such that a shift similar to the shift from the starting first field to the ending first field is repeated for each predetermined number of first fields, said slice control unit making the division (i) and the determination (ii) in a case where the current field is the first field; a reference image control unit configured to determine, in the case where the current field to be coded is the first field, that each P-slice located between the first end and the current I-slice or located at the first end of the current first field can refer to only a first field coded immediately before the current first field including the P-slice among first fields coded before the current first field, and to determine, in a case where the current field to be coded is the second field, that at least one second field included in a predetermined number of second fields can refer to only a first field coded immediately before at least one second field, the first fields referred to in both the case where the current field is the first field and the case where the current field is the second field being reference fields; and a coding unit configured to code all of the intra coding blocks included in each I-slice with reference to pixels within the I-slice, and code all of the inter coding blocks included in each P-slice with reference to either pixels within the field including the P-slice or pixels in a determined reference field of the reference fields.