Image filter, encoding device, decoding device, and data structure

Abstract

An image filter ( 100 ) for calculating a pixel value of target pixel in an output image from a pixel value of each of a pixel or pixels belonging to a filter area in an input image by using a filter coefficient vector V, is configured to include a filter coefficient vector changing section ( 120 ) for changing the filter coefficient vector V according to at least either where the target area is in the input image, or where the target pixel is in the output image.

1 - 16 . (canceled) 
     
     
         17 . An image filter for calculating a pixel value of target pixel in an output image from a pixel value of each of a pixel or pixels belonging to a target area in an input image, from a filter coefficient vector, and from an offset, comprising: filter coefficient changing means for changing the filter coefficient and the offset according to at least either where the target area is spacially in the input image, or where the target pixel is spacially in the output image. 
     
     
         18 . The image filter as set forth in  claim 17 , wherein the pixel value is a luminance value, and the filter coefficient changing means classifies the target area according to the luminance value, and sets, as the offset, a value determined by a result of the classification. 
     
     
         19 . The image filter as set forth in  claim 18 , wherein the target area in the input image includes only one pixel. 
     
     
         20 . The image filter as set forth in  claim 17 , wherein a filter coefficient vector, whose components are the filter coefficient and the offset, is dividable into a sum of (i) a fixed filter coefficient vector predetermined for every unit area constituting the output image, and (ii) a variable filter coefficient vector variable by the filter coefficient changing means according to at least either where the target area is spacially in the input image, or where the target pixel is spacially in the output image. 
     
     
         21 . The image filter as set forth in  claim 20 , wherein the variable filter coefficient vector is further dividable into (i) a fixed coefficient predetermined for every unit area constituting the output image, (ii) a variable coefficient variable by the filter coefficient changing means according to at least either where the target area is spacially in the input image, or where the target pixel is spacially in the output image, and (iii) a predetermined fixed vector. 
     
     
         22 . The image filter as set forth in  claim 21 , wherein:
 the variable coefficient is changed according to a degree of flatness in an image in the target area by the filter coefficient changing means; and   the fixed vector is a filter base having at least one of edge-stress effect and a blurring effect.   
     
     
         23 . The image filter as set forth in  claim 21 , wherein:
 the variable coefficient is changed according to an edge angle of an edge in an image in the target area by the filter coefficient changing means; and   the fixed vector is a filter base having at least one of edge-stress effect and a blurring effect.   
     
     
         24 . The image filter as set forth in  claim 21 , wherein:
 the variable coefficient is changed according to luminance of an image in the target area by the filter coefficient changing means; and   the fixed vector is a filter base having at least one of edge-stress effect and a blurring effect.   
     
     
         25 . The image filter as set forth in  claim 21 , wherein:
 the variable coefficient is changed by the filter coefficient changing means according to whether or not a block including the target area is a block to which a skip mode is applied; and   the fixed vector is a filter base having at least one of edge-stress effect and a blurring effect.   
     
     
         26 . The image filter as set forth in  claim 21 , wherein:
 the variable coefficient is changed by the filter coefficient changing means according to whether a block including the target area is an inter predicted block or an intra predicted block; and   the fixed vector is a filter base having at least one of edge-stress effect and a blurring effect.   
     
     
         27 . The image filter as set forth in  claim 21 , wherein components of the fixed filter coefficient vector, and the fixed coefficient are defined to minimize a difference between a certain image and the output image, where the input image is a decoded image obtained by encoding and decoding the certain image. 
     
     
         28 . The image filter as set forth in  claim 20 , wherein the fixed filter coefficient vector and the variable filter coefficient vector are orthogonal to each other. 
     
     
         29 . A decoding device comprising an image filter as set forth in  claim 17 , and causing the image filter to process a decoded image. 
     
     
         30 . An encoding device comprising an image filter as set forth in  claim 17 , and causing the image filter to process a locally decoded image. 
     
     
         31 . A data structure of an encoded data, which a decoding device refers to, the decoding device (i) including an image filter for calculating a pixel value of target pixel in an output image from a pixel value of each of a pixel or pixels belonging to a target area in an input image by using a filter coefficient vector, and (ii) causing the image filter to process a decoded image, the data structure comprising:
 a fixed coefficient, with which the decoding device multiplies a product of a predetermined fixed vector and a variable coefficient variable according to at least either where the target area is spacially in the input image, or where the target pixel is spacially in the output image; and   components of a fixed filter coefficient vector to which the decoding device adds a product of the variable coefficient, the fixed vector, and the fixed coefficient, the fixed filter coefficient vector being predetermined for every unit area constituting the output image.   
     
     
         32 . A data structure of encoded data, which a decoding device refers to, the decoding device (i) including an image filter for calculating a luminance value of a target pixel in an output pixel from a luminance value of each of a pixel or pixels belonging to an input image, from a filter coefficient, and from an offset, and (ii) causing the image filter to process a decoded image, wherein:
 the offset is set according to the luminance value; and   the encoded data includes the offset.