Moving image coder

Claim 2

A moving image coder as claimed in claim 1, wherein the prediction error amounts from the forward predicting motion vector/prediction error amount detecting section (101) and the backward-predicting motion vector/prediction error amount detecting section (102) are compared with each other in the comparator/mode selecting section (104) by a differential value between these prediction error amounts.

Claim 3

A moving image coder as claimed in claim 1, wherein the prediction error amounts from the forward predicting motion vector/prediction error amount detecting section (101) and the backward-predicting motion vector/prediction error amount detecting section (102) are compared with each other in the comparator/mode selecting section (104) by a ratio of these prediction error amounts.

Claim 4

A moving image coder as claimed in claim 1, wherein the prediction error amounts from the forward predicting motion vector/prediction error amount detecting section (101) and the backward-predicting motion vector/prediction error amount detecting section (102) are compared with each other in the comparator/mode selecting section (104) by combining a differential value between these prediction error amounts with a ratio of these prediction error amounts.

Claim 5

A moving image coder as claimed in any one of claims 1 to 4, wherein the moving image coder further comprises: an odd/even field separating section (501) for separating odd and even fields from each other; a forward field predicting motion vector/prediction error amount detecting section (505) for detecting a forward field predicting motion vector and a prediction error amount every each of the separated odd and even fields; a backward field predicting motion vector/prediction error amount detecting section (504) for detecting a backward field predicting motion vector and a prediction error amount; and a comparator/mode selecting section (506).

Claim 6

A moving image coder as claimed in any one of claims 1 to 4, wherein the moving image coder is arranged in a frame/field adaptive predicted moving image coder having six kinds of prediction modes obtained by combining three prediction modes composed of said forward prediction mode, said backward-prediction mode and said bidirectional prediction mode with two prediction modes composed of a frame prediction mode and a field prediction mode; the frame/field adaptive predicted moving image coder comprises: said forward frame predicting motion vector/prediction error amount detecting section (502) ; said backward frame predicting motion vector/prediction error amount detecting section (503) ; said odd/even field separating section (501) ; said forward field predicting motion vector/prediction error amount detecting section (505) ; said backward field predicting motion vector/prediction error amount detecting section (504) ; and said comparator/mode selecting section (506), and this comparator/mode selecting section (506) determines selection of any one of the forward prediction mode, the backward-prediction mode and the bidirectional prediction mode after the frame prediction mode or the field prediction mode is determined in use.

Claim 7

A moving image coder as claimed in claim 6, wherein each of the frame prediction mode and the field prediction mode in the comparator/mode selecting section (506) is selectively set to a frame/field mode in a prediction system for providing a minimum prediction error amount among a forward frame prediction error amount, a forward field prediction error amount, a backward frame prediction error amount and a backward field prediction error amount; the forward field prediction error amount is set to a sum of a forward directional odd field prediction error amount and a forward directional even field prediction error amount with respect to the same block as an object block of said forward frame prediction; and the backward field prediction error amount is set to a sum of a backward directional odd field prediction error amount and a backward directional even field prediction error amount with respect to the same block as an object block of said backward frame prediction.

Claim 8

A moving image coder as claimed in claim 6, wherein a sum of said forward frame prediction error amount and said backward frame prediction error amount is compared with a sum of said forward directional odd field prediction error amount, said forward directional even field prediction error amount, said backward directional odd field prediction error amount and said backward directional even field prediction error amount; and each of the frame prediction mode and the field prediction mode in the comparator/mode selecting section (506) is selectively set to a frame/field mode in a prediction system for providing a smaller prediction error amount among said two sums.

Claim 9

A moving image coder as claimed in any one of claims 1 to 4, wherein the moving image coder is arranged in a frame/field adaptive predicted moving image coder having six kinds of prediction modes obtained by combining three prediction modes composed of said forward prediction mode, said backward-prediction mode and said bidirectional prediction mode with two prediction modes composed of a frame prediction mode and a field prediction mode; the frame/field adaptive predicted moving image coder comprises: said forward frame predicting motion vector/prediction error amount detecting section (502) ; said backward frame predicting motion vector/prediction error amount detecting section (503) ; said odd/even field separating section (501) ; said forward field predicting motion vector/prediction error amount detecting section (505) ; said backward field predicting motion vector/prediction error amount detecting section (504) ; and said comparator/mode selecting section (506), and a sum of said forward frame prediction error amount, said forward directional odd field prediction error amount and said forward directional even field prediction error amount, and a sum of said backward frame prediction error amount, said backward directional odd field prediction error amount and said backward directional even field prediction error amount are input to said comparator/mode selecting section (506) ; and selection of the frame prediction mode or the field prediction mode is determined by selecting a smaller one of said frame prediction error amount and the field prediction error amount as a sum of said odd field prediction error amount and said even field prediction error amount after one of the forward prediction mode, the backward-prediction mode and the bidirectional prediction mode is determined in use.