NZ332342A - Compression of line scan image data - Google Patents

Abstract

A compression system compresses a sequence of digital data frames, each data frame forming a column of n-bit greyscale numbers representative of luminance values detected at pixels of a line sensor on which a fixed line portion of a scene is imaged in a video camera; the sequence forming an array of rows of n-bit numbers. The compression system includes a greyscale converter for converting each of the digital data frames into a column of m-bit greyscale numbers, m being less than n, to form an array of rows of m-bit numbers. A counter counts the number of occurrences of equivalent m-bit greyscale numbers A, A, B, B etc in adjacent frames in each row of the array of rows of m-bit numbers, and each row of the array is reformatted Fig 7A so that every row sequence of equivalent m-bit numbers is represented by one m-bit number value, e.g. A and the count e.g. 16. Each reformatted row is sequentially stored in a memory Fig 7B so that the memory required to store the sequence of digital data frames representing the fixed line portion of the imaged visual field is reduced.