Patent ID: 6195128
Filing Date: 2001-02-27
Classification: H04N

Abstract:
A method of processing digital video information in an adapted format for transmission or storage after compression; said method comprising:reading digital data representing individual picture elements (pixels) of a video image frame as a series of binary coded words;deriving from the words representing individual pixels further words each describing first and second groups of pixels of which the second groups are contained in corresponding first groups and include representations of a luminance of 2.times.2 pixel blocks;comparing and evaluating the words of the second groups representing corresponding portions of one frame with another frame or other frames in a predetermined sequential order of the elements making up successive first groups to detect whether significant change has occurred;using the comparison to take the second group to represent all the individual pixels described by the first group whenever the detected change is significant andusing variable length code words to represent a number of consecutive components of the second groups without significant change;characterized in that each of the representations of the luminance of the 2.times.2 pixel block takes a form of a pair of luminance values and an indication as to which of these two values comprising the pair of luminance values is to be chosen and the comparing and evaluating step comprises ascertaining whether the indications have changed to signify that a significant change has occurred and if not then information is derived by combining the pairs of luminance values and processing such combined values to produce fresh code words including the respective differences between maximum and minimum luminance values and combining the fresh code words with said indications to produce further code words which are then processed to produce said information which represents the significance of the difference between the luminance values in the 2.times.2 pixel blocks being compared and utilizing this information to decide whether the significance of the difference should be taken as a significant change.