Patent ID: 6243419
Filing Date: 2001-06-05
Classification: G06F,G06K,H04N

Abstract:
A method for detecting a caption region from video data coded by using a combination of predictive coding and motion compensation, comprising the steps of:judging whether each pixel/block in the video data is coded by using inter-frame correlation without using motion compensation or not; anddetecting a region in the video data at which pixels/blocks judged by the judging step as being coded by using inter-frame correlation without using motion compensation are concentrated time-wise and space-wise, as a caption region;wherein the detecting step includes the steps of:counting a frequency of appearance of a pixel/block which is judged by the judging step as being coded by using inter-frame correlation without using motion compensation, at each pixel/block position of a frame over a prescribed counting period;selecting the caption region by comparing the frequency of appearance counted by the counting step with a prescribed threshold value;forming a two-dimensional counting matrix indicating the frequency of appearance at each pixel/block position as counted by the counting step; andproducing a projection histogram by projecting the counting matrix into at least one direction defining the counting matrix;wherein the producing step obtains a first projection histogram by projecting the counting matrix into a first direction, determines a first action along the first direction in which the frequency of appearance as indicated by the first projection histogram is greater than a first prescribed threshold value, and obtains the projection histogram by projecting the first projection histogram into a second direction within the first section; andwherein the selecting step compares the frequency of appearance as indicated by the projection histogram with the prescribed threshold value, and determines a second section along the second direction in which the frequency of appearance as indicated by the projection histogram is greater than the prescribed threshold value, and selects those pixels/blocks which are within the first section and the second section as the caption region.