Patent ID: 7248632
Filing Date: 2007-07-24
Classification: H04N

Abstract:
1. A bandwidth-independent method for recording and transmitting video images, comprising the steps of: inputting a first analog video image from a camera device into a transmitter system; digitizing said first analog video image to a first bit map frame and dividing said first frame into a first plurality of individual blocks to define a reference frame; inputting a second analog video image from a camera device into a transmitter system; digitizing said second analog video image to a second bit map frame and dividing said second frame into a second plurality of individual blocks to define a current frame; performing a discrete cosine transform (DCT) to convert each of said first and second plurality of blocks from a time domain to a frequency domain, each block subsequent to said DCT being represented by a sum of sines and cosines preceded by a DC coefficient and a plurality of AC coefficients; truncating higher order AC coefficients within said plurality of AC coefficients to effect lossy compression of said sum; for each block, comparing the DC coefficient from the reference frame with the DC coefficient for a corresponding block in the current frame; for each block, comparing a first plurality of AC coefficients from said reference frame with a second plurality of AC coefficients for the corresponding block from said current frame; identifying any blocks within said plurality of blocks for which a difference between said DC coefficients exceeds a threshold value as a changed DC coefficient; identifying any blocks within said plurality of blocks for which a difference between at least one of said first and second pluralities of AC coefficients exceeds a threshold value as changed blocks; transmitting at least one of said changed DC coefficient and said changed blocks to a receiver or storage device as changes, unchanged blocks not being transmitted; and updating the reference frame with any changes.