Video sequence processing

Abstract

An array of pixel-to-pixel dissimilarity values is analysed to select a pixel which has a low pixel-to-pixel dissimilarity value and which has neighbouring pixels which have a low pixel-to-pixel dissimilarity value. Each pixel-to-pixel dissimilarity value represents a difference between the value of a pixel in a first spatial pixel array representing a first image and the value of a corresponding pixel in a second spatial pixel array representing a second image. The pixels neighbouring the current pixel are divided into at least two polar sectors. The current pixel is selected when the current pixel and the pixels of at least one polar sector have low dissimilarity values.

1 . In a video processor, a method of analysing an array of pixel-to-pixel dissimilarity values to select a pixel which has a low pixel-to-pixel dissimilarity value and which has neighbouring pixels which have a low pixel-to-pixel dissimilarity value; the method comprising the steps of:
 receiving a spatial array of pixel-to-pixel dissimilarity values, each pixel-to-pixel dissimilarity value representing a difference between the value of a pixel in a first spatial pixel array representing a first image and the value of a corresponding pixel in a second spatial pixel array representing a second image;   dividing the pixels neighbouring the current pixel into at least two polar sectors; and   selecting the current pixel when the current pixel and the pixels of at least one polar sector have low dissimilarity values.   
     
     
         2 . The method according to  claim 1  in which each dissimilarity value is a rectified field difference between fields displaced through motion compensation. 
     
     
         3 . The method according to  claim 1  in which the polar sectors are non-overlapping. 
     
     
         4 . A video sequence processing apparatus for analysing motion-compensated pixel-to-pixel dissimilarity values, the apparatus comprising
 a spatial filter configured to operate on motion-compensated pixel-to-pixel dissimilarity values in which the filter aperture which defines those values on which the filter operates is decomposed into two or more polar sectors and the filter comprises a plurality of partial filters applied respectively to each sector; and   a combiner for combining the respective outputs of said partial filters by a non-linear operation.   
     
     
         5 . The apparatus according to  claim 4  in which the combiner operates to taking minimum values of partial-filter outputs from pairs of sectors that are diametrically opposite each other in the filter aperture. 
     
     
         6 . The apparatus according to  claim 4  in which the partial filtering operation is a rank-order operation. 
     
     
         7 . The apparatus according to  claim 4  in which the partial filtering operation is an averaging operation. 
     
     
         8 . The apparatus according to  claim 4  in which the minimum values from pairs of sectors are processed by a rank-order operation. 
     
     
         9 . The apparatus according to  claim 4  in which the minimum values from pairs of sectors are processed by an averaging operation. 
     
     
         10 . A non-transitory computer readable medium comprising computer-readable instructions that when executed by a programmable apparatus implement a method of analysing an array of pixel-to-pixel dissimilarity values to select a pixel which has a low pixel-to-pixel dissimilarity value and which has neighbouring pixels which have a low pixel-to-pixel dissimilarity value; the method comprising the steps of:
 receiving a spatial array of pixel-to-pixel dissimilarity values, each pixel-to-pixel dissimilarity value representing a difference between the value of a pixel in a first spatial pixel array representing a first image and the value of a corresponding pixel in a second spatial pixel array representing a second image;   dividing the pixels neighbouring the current pixel into at least two polar sectors; and   selecting the current pixel when the current pixel and the pixels of at least one polar sector have low dissimilarity values.