Methods and apparatus for detecting scenes in a video medium

1. A method of detecting one or more scenes in a video medium, the video medium defining an array of pixels for displaying its video content and comprising a sequence of video frames, each video frame having a set of pixel data values for representing an image on the array of pixels, each pixel data value being associated with a pixel in the array, the method comprising the steps of:

(a) selecting a plurality of video frames from the video medium, the selected video frames having a sequential order related to the order in which they occur in the video medium];

(b) obtaining the pixel data values of a subset of pixels of each selected video frame, the pixel subsets of at least one pair of successive selected video frames having a difference in the selection of pixels;

(c) generating a dispersion signal representative of the dispersion in the obtained pixel data values over a group of sequential selected video frames;

(d) generating a scene-detection signal having a first state indicating the presence of a scene and a second state indicating the absence of a scene, the scene-detection signal being generated as a function of at least the dispersion signal and a threshold level; and

wherein step (c) comprises:

(e) generating a first video content value for each selected video frame as a first function of the obtained pixel data values for the selected video frame and a second video content value for each selected video frame as a second function of the obtained pixel data values for the selected video frame;

(f) generating the first dispersion signal as a third function of the first video content values over the group of sequential selected video frames; and

(g) generating a second dispersion signal as a fourth function of the second video content values over the group of sequential selected video frames; and

wherein step (d) comprises the step of generating the scene-detection signal in its second state when both the first and second dispersion signals are below respective threshold levels, and the step of generating the scene-detection signal in its first state when one or more of the dispersion signals are above their respective threshold levels; and further comprising

(h) providing the scene-detection signal to indicate the presence and absence of the scene.

2. The method of claim 1 wherein the first function produces the same value with each of the pixel subsets when the selected video frame is uniformly painted with a color at a uniform luminescence, and produces different values with at least two of the pixel subsets when the selected video frame has a non-uniform color.

3. The method of claim 2 wherein the first function produces respective values when a selected video frame is uniformly painted with different respective colors at a uniform luminescence, each respective value being the same with each of the pixel subsets.

4. The method of claim 1 wherein the first function produces the same value with each of the pixel subsets when the selected video frame is uniformly painted with a color at a uniform luminescence, and produces different values with at least two of the pixel subsets when the selected video frame has a non-uniform luminescence.

5. The method of claim 4 wherein the first function produces respective values when a selected video frame is uniformly painted with different respective luminescence values of the same color, each respective value being the same with each of the pixel subsets.

6. The method of claim 1 wherein the pixel data values are in YUV format, and wherein the first function comprises the summation of the Y-values of a pixel subset.

7. The method of claim 1 wherein the pixel data values are in YUV format;

wherein step (e) further comprises the step of concatenating the Y-, U-, and V-bytes of each obtained pixel data value to form a concatenated value; and

wherein the first function comprises the summation of the concatenated values of a pixel subset.

8. The method of claim 1 wherein step (f) generates an average of the video content values for the group of sequential selected video frames, and wherein the second function generates the dispersion signal in relation to a variance of the video content values from the average.

9. The method of claim 1 wherein step (f) generates a central tendency value of the video content values for the group of sequential selected video frames, and wherein the second function generates the dispersion signal in relation to a deviation of the video content values from the central tendency value.

10. The method of claim 1 wherein the second function generates the dispersion signal as the difference between the maximum and minimum of the video content values in the group of sequential selected video frames.

11. The method of claim 1 wherein step (a) selects all of the video frames in a sequence of video frames of the video medium.

12. The method of claim 1 wherein step (a) selects a reduced number of video frames in a periodic manner from a sequence of video frames of the video medium.

13. The method of claim 1 wherein step (a) selects a reduced number of video frames in an aperiodic manner from a sequence of video frames of the video medium.

14. The method of claim 1 wherein the number of pixels in a pixel subset is not more than 1% of the total number of pixels in the selected video frame.

15. The method of claim 1 wherein the number of pixels in a pixel subset ranges from 200 to 800.

16. The method of claim 1 wherein at least 25% of the pixels in the pixel subsets for each pair of successive selected video frames are different.

17. The method of claim 1 wherein at least 50% of the pixels in the pixel subsets for each pair of successive selected video frames are different.