METHOD FOR NOISE REDUCTION IN IMAGES IN AN IMAGE SEQUENCE

摘要

The invention relates to a method for noise suppression in images of an image sequence.;It is an object of the invention to find how an iteratively better adapted noise suppression can be ensured for images of an image sequence, in particular given a rising number of images.;According to the invention, this object is achieved by a method for noise suppression which provides a low-pass filter algorithm:;Pi,jn+1=αi,jn+1*Pi,jn+(1−αi,jn+1)*Qi,jn+1 ;with an attenuation function αi,jn+1=αi,jn+1(α0i,jn+1,Γi,jn+1).

主权项

1. A method for noise suppression in images of an image sequence in accordance with the following algorithm:
Pi,jn+1=αi,jn+1*Pi,jn+(1−αi,jn+1)*Qi,jn+1 where: Pi,jn+1=grayscale value of a pixel of the ith row and the jth column after the (n+1)th iteration,
Pi,jn=grayscale value of a pixel of the ith row and the jth column after the (n)th iteration, Qi,jn+1=grayscale value of a pixel of the ith row and the jth column after the (n+1)th recording (unfiltered), and di,jn+1=attenuation function for a pixel in the ith row and the jth column,the algorithm being a recursive law-pass with an attenuation function αi,jn+1 adapted for the pixel, and the action of the attenuation being dependent on a grayscale value difference dQi,jn+1=|Pi,jn−Qi,jn+1| between. filtered and unfiltered pixels, on an amplitude of the grayscale value Qi,jn+1 of the pixel, it further being the case that:γi,jn+1{=Q0Qi,jn+1[forQi,jn+1>Q0]=1[forotherwise]where γi,jn+1=weighting factor, and
Q0—reference grayscale value,characterised in that
an adaptation of the strength of the attenuation factor α0i,jn+1 is performed taking account of the sequence length in which a pixel of the ith row and the jth column has an unchanged grayscale value, the attenuation factors α0i,jn+1 with a limiting value α0min and a limiting value α0max are defined, a movement measureΓi,jn+1{=Qi,jn+1dif_swl*γi,jn+1[forQi,jn+1*γi,jn+1