Significant scene detection and frame filtering for a visual indexing system using dynamic thresholds
View Patent ↗A video indexing system analyzes contents of source video and develops a visual table of contents using selected images. A system for detecting significant scenes detects video cuts from one scene to another, and static scenes based on DCT coefficients and macroblocks. A keyframe filtering process filters out less desired frames including, for example, unicolor frames, or those frames having a same object as a primary focus or one primary focuses. Commercials may also be detected and frames of commercials eliminated. The significant scenes and static scenes are detected based on a threshold which is set based on the category of the video.
1. A video system, comprising:
a receiver which receives frames of video;
a threshold memory which receives a threshold for a particular category of the video, wherein the threshold is based on an amount of action typically found in the particular category, the threshold being received from a program guide; and
a comparator which compares a first frame to a subsequent frame to determine a difference between the first and subsequent frames and compares the difference to the threshold, wherein if the difference is greater than the threshold then a scene change is deemed to have occurred between the two frames, and wherein if the difference is lower than the threshold then a scene change is deemed not to have occurred.
2. The video system in accordance with claim 1 , wherein if the difference is lower than the threshold for a plurality of frames the scene is deemed a static scene.
3. The video system in accordance with claim 1 , wherein the threshold is set at the receiver.
4. The video system in accordance with claim 1 , further comprising:
a category detector for detecting the category of the video; and
a threshold setter for setting the threshold based on the category detected.
5. The video system as claimed in claim 1 , wherein the threshold is automatically changed if a number of detected scene changes is above a predetermined number.
6. The video system as claimed in claim 1 , wherein the threshold is automatically changed if a number of detected scene changes is below a predetermined number.
7. The video system of claim 1 , further comprising a keyframe filterer which receives key frames from each scene change and filters out at least one of i) redundant, ii) similar and iii) unicolor key frames.