Method and apparatus for reducing the inherently dark grid pattern from

Abstract

A method and apparatus for improving an image received from a endoscope having a flexible fiber optic bundle that produces an interstitial grid overlay due to the dead space between each fiber pixel. The interstitial grid pattern in the image, is substantially eliminated by processing the image through a linear digital filter to attenuate the first-order spatial frequency components that contribute most to the interstitial pattern. The filter employs relatively small convolution kernels that are optimized for specific fiber spacing. The image is then processed through the linear digital filter by convolving the respective pixels in the image by the derived coefficients. The image is improved and the grid pattern may also be reduced by a dilation process which involves processing the image through a dilation algorithm to 'grow' the bright center of each fiber pixel in the image so that the effect of the grid pattern is reduced. The process involves filling in the dark area of the grid space with the color and intensity from the nearest fiber center to obtain an equivalent image representation. The dilation process uses a non-linear image processing algorithm to replace each pixel with the maximum pixel brightness in its immediate neighborhood depending on the selection of a kernel. The dilation kernel is selected by determining the number of detector (CCD) pixels that fit in a space between the fiber cores and then selecting a matrix size and kernel pattern.