Patent Document ID: 9685056
Application ID: 14504424
Patent Status: 1

Claim One:
1. A method for detecting change, comprising: a) receiving, by a processor, a video image from a video stream and a reference image; b) dividing, by the processor, the video image into non-overlapping blocks and the reference image into non-overlapping blocks; c) performing, by the processor, orthogonal transformations on a first corresponding pair of blocks to produce an orthogonally transformed pair of blocks, wherein a corresponding pair includes a first block in the video image and a first block in the reference image corresponding to the first block in the video image; d) modifying, by the processor, the orthogonally transformed pair of blocks by zeroing average value components in the orthogonally transformed pair of blocks; e) determining, by the processor, an infinity-norm difference between the modified orthogonally transformed pair of blocks by: subtracting each component in the first block in the video image, from a corresponding component in the first block in the reference image; determining an absolute value of each subtraction; and selecting the maximum value from the resulting absolute values, f) comparing the determined infinity-norm difference to a first threshold; and g) if the determined infinity-norm difference is greater than the first threshold, repeating steps c)-e) for a second corresponding pair of blocks, wherein the second corresponding pair of blocks includes a second block in the video image and a second block in the reference image corresponding to the second block in the video image, and wherein the second block in the video image overlaps with the first block in the video image and the second block in the reference image overlaps with the first block in the reference image.