Patent ID: 8731312

Claim:
An image coding apparatus, comprising: a judgment part for judging whether a macroblock to be coded should be intra-coded or inter-coded so that all macroblocks are intra-coded once in N frame period; and a coding part for coding said macroblock to be coded, on the basis of a determination result of said judgment part, wherein said judgment part includes a first conversion part for extracting the lower-order K bits of a numerical value J to thereby generate a numerical value L which can take a value of 2 K and converting said numerical value L into a numerical value M which can take a value of 2 K , assuming that a frame number of a coding object frame including said macroblock to be coded in said N frame period is represented by a binary number as said numerical value J; a second conversion part for extracting the lower-order K bits of a numerical value P to thereby generate a numerical value Q which can take a value of 2 K and converting said numerical value Q into a numerical value R which can take a value of 2 K , assuming that the coordinate of said macroblock to be coded in a first direction in said coding object frame is represented by a binary number as said numerical value P; a generation part for generating a numerical value S which is uniquely determined from a combination of said numerical value M and said numerical value R; and a determination part for extracting the lower-order K bits of a numerical value T to thereby generate a numerical value U which can take a value of 2 K and determining said macroblock to be coded as an intra macroblock when said numerical value S and said numerical value U are identical to each other, assuming that the coordinate of said macroblock to be coded in a second direction orthogonal to said first direction in said coding object frame is represented by a binary number as said numerical value T.