ENHANCEMENT OF IMAGES USING RECURSIVE FILTERS

摘要

A method of obtaining a spatial low pass filtered images, herein also referred to as an LF images, from the video output from a video camera video camera comprising a sensor array and operable to produce successive video frames in the form of pixelated 2D images, also referred to herein as raw images, each said raw image having a first predetermined number of rows of pixels and a second predetermined number of columns of pixels, the method including creating said LF images, (i.e. images only containing the lower spatial frequencies of said 2D images), from said raw or sensor images, in real time, the method characterised by scanning the sensor array row by row, and deriving the value of each pixel of said LF image, herein referred to as the LF value, in such a way that said LF value of a pixel is dependent on at least all earlier scanned pixels of the current row and all earlier scanned rows, but is not dependent on the pixels of rows located below a pixel row which is a third predetermined number of rows below the current row, said third predetermined number being significantly less than said first predetermined number, for example being less than one fifth of said first predetermined number.