US 5,856,848 AGranted

Moving image coder

AssigneeSharp Kabushiki Kaisha

InventorsYoichi Fujiwara, Toshiyuki Miyake, Hiroyuki Katata, Tomoko Aono, Hiroshi Kusao

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Abstract

A moving image coder has an arithmetic unit for calculating an average value of a coding object block; an arithmetic unit for obtaining an alternating current component by subtracting the average value from each of pixel values of the coding object block; an arithmetic unit for obtaining a intra frame activity amount by making a calculation of the same kind as an error calculation in a motion prediction with respect to the obtained alternating current component; and a comparator for comparing the intra frame activity amount with a predicting error amount calculated when the motion prediction is made. The inter frame coding mode or the intra frame coding mode is judged by large and small relations of the predicting error amount and the intra frame activity amount. In this moving image coder, codings of a intra frame block and a inter frame differential block are adaptively switched in a small hardware scale.

Claims9

Dependent claims

A moving image coder in which an image is divided into image blocks and a coding mode is selected from among an inter frame coding mode and an intra frame coding mode, the inter frame coding mode using an inter frame difference block as a coding object, and the intra frame coding mode using said coding image block as said coding object, said moving image coder comprising:

motion prediction means for obtaining a prediction block by setting a motion vector to be minimized and calculating a predicting error amount obtained by a predetermined error calculation with respect to each of inter frame difference signals between a candidate block of said prediction block and a corresponding coding image block;
means for calculating an average value of said coding image block;
means for obtaining alternating current components by subtracting said average value from each pixel value in said coding image block;
means for obtaining an intra frame activity amount obtained by said predetermined error calculation used in said motion prediction means with respect to each of said alternating current components;
comparing means for comparing said predicting error amount calculated by said motion prediction means with said intra frame activity amount;
determining means for determining said coding mode in accordance with the result of said comparing means;
and
coding means for coding said coding image block using the determined coding mode, wherein said coding image block is capable of a different coding mode than an adjacent coding image block of the image,
and said determining means determines said coding mode for every coding image block.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/882,114Filed 25 Jun 1997 · continuation
Priority: JP 5-33847428 Dec 1993
Granted: 5 Jan 1999
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

H04N 19/42
Methods or arrangements for coding, decoding, compressing or decompressing digital video signals: characterised by implementation details or…
H04N 19/107
Selection of coding mode or of prediction mode: between spatial and temporal predictive coding, e.g. picture refresh
H04N 19/61
Using transform coding: in combination with predictive coding
H04N
Pictorial communication