Patent ID: 7729559

Claim:
An image generation method, comprising: generating a first output image based on a plurality of input images; determining a contribution of an artefact to image intensity values of the first output image by determining values of coefficients of an equation representing a sinusoidal variation in one of a horizontal and a vertical direction; generating, by means of a processor, a second output image based on the first output image, the second output image being the same as the first output image less the artifact, including subtracting the contribution from the image intensity values, the subtraction including: determining values of the equation by plugging the determined coefficients into the equation; and subtracting the equation values from the image intensity values; and the equation values vary between one of pixel rows and pixel columns; wherein: the artefact is formed by a number of harmonics m of a grid pattern of at least one of the input images; the equation is a 1 cos(ωy)+b 1 sin(ωy)+ . . . a m cos(mωy)+b m sin (mωy), wherein a 1 . . . a m and b 1 . . . b m are the coefficients, ω is an angular frequency of the grid pattern, and y is one of a pixel row number, which differs for each pixel row, and a pixel column number, which differs for each pixel column; and wherein the coefficients are determined by applying a regression analysis to matrices Q, b, and G; Q = [ q 1 q 2 q 3 ⋮ q x ] , wherein q is a sampled pixel intensity value of the first output image and x is a number of pixels sampled; b = [ I a 1 b 1 ⋮ a m b m ] , wherein I represents a sampled pixel intensity value less the artefact's contribution to the sampled pixel intensity; and G = [ 1 cos ⁡ ( ω ⁢ ⁢ y i ) sin ⁡ ( ω ⁢ ⁢ y i ) cos ⁡ ( 2 ⁢ ω ⁢ ⁢ y i ) sin ⁡ ( 2 ⁢ ω ⁢ ⁢ y i ) cos ⁡ ( 3 ⁢ ω ⁢ ⁢ y i ) sin ⁡ ( 3 ⁢ ω ⁢ ⁢ y i ) 1 cos ⁡ ( ω ⁢ ⁢ y i ) sin ⁡ ( ω ⁢ ⁢ y i ) cos ⁡ ( 2 ⁢ ω ⁢ ⁢ y i ) sin ⁡ ( 2 ⁢ ω ⁢ ⁢ y i ) cos ⁡ ( 3 ⁢ ω ⁢ ⁢ y i ) sin ⁡ ( 3 ⁢ ω ⁢ ⁢ y i ) 1 cos ⁡ ( ω ⁢ ⁢ y i ) sin ⁡ ( ω ⁢ ⁢ y i ) cos ⁡ ( 2 ⁢ ω ⁢ ⁢ y i ) sin ⁡ ( 2 ⁢ ω ⁢ ⁢ y i ) cos ⁡ ( 3 ⁢ ω ⁢ ⁢ y i ) sin ⁡ ( 3 ⁢ ω ⁢ ⁢ y i ) ⋮ 1 cos ⁡ ( ω ⁢ ⁢ y i ) sin ⁡ ( ω ⁢ ⁢ y i ) cos ⁡ ( 2 ⁢ ω ⁢ ⁢ y i ) sin ⁡ ( 2 ⁢ ω ⁢ ⁢ y i ) cos ⁡ ( 3 ⁢ ω ⁢ ⁢ y i ) sin ⁡ ( 3 ⁢ ω ⁢ ⁢ y i ) ] , wherein each row of the G matrix is associated with a corresponding value of the q matrix, and wherein, for each row of the G matrix, y i is one of a row number and a column number of the G matrix row's corresponding q matrix value.