An example of a video descriptor generation device is disclosed in Patent Document 1. FIG. 27 is a block diagram showing a video descriptor generation device described in Patent Document 1.
An each-frame feature extraction unit 10 calculates a frame unit feature from an input video, and outputs it to a feature table creation unit 20. The feature table creation unit 20 creates a feature table from the frame unit feature output from the each-frame feature extraction unit 10, and outputs the feature table as a video descriptor.
Next, operation of the device shown in FIG. 27 will be described.
The each-frame feature extraction unit 10 performs a process of extracting a feature such as the color of each frame from an input video, and outputs the obtained feature to the feature table creation unit 20 as a frame unit feature.
The feature table creation unit 20 performs processing on variations in the feature between frames using a threshold, and compresses the feature in a time direction. Specifically, the feature table creation unit 20 calculates a difference between the frame unit features of frames, and determines whether or not the difference is within a certain allowable variation range. Then, the feature table creation unit 20 divides the video into time segments in which the video is within the allowable variation range, and for each of the divided time segments, a set of the feature and the time segment length (the number of frames) is output as a video descriptor.
As such, the feature of the video obtained for each frame can be compressed in a time direction, whereby the feature size can be reduced. Further, high-speed matching can also be realized.
Patent Document 1: Japanese Unexamined Patent Publication No. 10-320400