Picture coding method and picture decoding method

Abstract

A picture coding apparatus ( 300 ) is a picture coding apparatus that codes a difference between picture data (Img) representing an input picture and predictive picture data (Pred) representing a predictive picture for the input picture and generates coded picture data, and includes a picture decoding unit ( 104 ) for decoding coded picture data (Img) after the picture data (Img) is coded; inter pixel filters A and B ( 303 and 304 ) for performing inter pixel filter operation for decoded picture data (Recon) obtained by the picture decoding unit ( 104 ); switches ( 301 and 302 ) for selecting one of the inter pixel filters; and an inter picture predicting unit ( 108 ) for generating the predictive picture data (Pred) for the input picture data (Img) using filtered decoded picture data (FilteredImg 1 ), as reference picture data (Ref), obtained by the selected inter pixel filter.

1 - 57 . (canceled) 
     
     
         58 . A method for coding a picture, said method comprising:
 coding an input picture to obtain coded data with or without using a reference picture;   decoding the coded data to obtain a decoded picture;   changing a filtering of the decoded picture based on information indicating whether or not the decoded picture is used as a reference picture to code a following input picture; and   storing the decoded picture, which is filtered, for use as the reference picture to code a following input picture,   wherein a smoothing level of the filtering performed when the decoded picture is used as a reference picture is higher than a smoothing level of the filtering performed when the decoded picture is not used as a reference picture.   
     
     
         59 . The coding method according to  claim 58 ,
 wherein the filtering is not performed on the decoded picture when the decoded picture is not used as a reference picture.   
     
     
         60 . A method for coding a picture, said method comprising:
 coding a target picture to obtain coded data;   decoding the coded data to obtain a decoded picture;   determining picture type information, the picture type information indicating whether a following input picture is to be coded with using the decoded picture as a reference picture or without using the decoded picture as a reference picture;   switching a filter characteristic based on the picture type information;   filtering the decoded picture using the switched filter characteristic to obtain a filtered picture; and   storing the filtered picture for use as a reference picture to code the following input picture,   wherein a smoothing level of the filter characteristic when the picture type information indicates that the decoded picture is used as a reference picture is higher than a smoothing level of the filter characteristic when the picture type information indicates that the decoded picture is not used as a reference picture.   
     
     
         61 . The coding method according to  claim 60 ,
 wherein the filtering is not performed on the decoded picture when the decoded picture is not used as a reference picture.