Motion detection method and apparatus

• US 6,144,770 A
• Filed: 06/03/1999
• Issued: 11/07/2000
• Est. Priority Date: 12/21/1995
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Lennon, Alison
• Primary Examiner(s): Couso, Jose L.
• Assistant Examiner(s): Do, Anh Hong
• Application Number:
  US09/324,650
• Time in Patent Office: 523 Days
• Field of Search: 382/236, 382/238, 382/232
• US Class Current: 382/236
• CPC Class Codes: G06T 7/262 using transform domain methods, e.g. Fourier domain methods
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals

Abstract

The present invention provides a method and apparatus for detecting motion in an input sequence of images. Each image comprises a number of lines and each line has a number of pixels. Values of a region of pixels of a current image are transformed to determine a set of representation values. The set of representation values are indicative of the region of pixels at a number of resolution levels. The set of representation values of the region of pixels of the current image are compared with a set of representation values of a corresponding region of pixels from a stored previous image. Based on the comparing step, a difference measure is determined between the region of pixels and the corresponding region of pixels that is indicative of the presence or absence of motion in the current image.

Claims

1. An apparatus for detecting motion in an input sequence of images, each image comprising a plurality of pixels, said apparatus comprising:

transforming means for transforming values of pixels to representation values at a plurality of different resolution levels;

comparing means for comparing and iteratively determining a difference measure between said representation values for at least two of said plurality of different resolution levels, of a current image, and corresponding representation values from a previous image; and

detection means for detecting motion in said current image in accordance with said difference measure determined by said comparing means.

2. An apparatus according to claim 1, wherein said transforming means comprises means for wavelet transforming said values of said pixels to form said set of representation values.

3. An apparatus according to claim 2, wherein said wavelet transforming means is adapted to implement one of the group consisting of Haar and Daubechies transforms.

4. An apparatus according to claim 1, wherein said values of pixels are color values of the pixels.

5. An apparatus according to claim 1, wherein said values of pixels are luminance and chrominance values of pixels.

6. An apparatus according to claim 1, further comprising providing means for providing an image signal from said input sequence of images in accordance with the result of said detecting means.

7. An apparatus according to claim 1, wherein said current image is processed as a plurality of blocks.

8. An apparatus according to claim 6, further comprising display means for displaying the image signal provided by said providing means.

9. An apparatus according to claim 8, wherein said display means is a liquid crystal display.

10. A method for detecting motion in an input sequence of images, each image comprising a plurality of pixels, said method comprising the steps of:

transforming values of pixels to representation values at a plurality of different resolution levels;

comparing and iteratively determining a difference measure between said representation values for at least two of said plurality of different resolution levels, of a current image, and corresponding representation values from a previous image; and

detecting motion in said current image in accordance with said difference measure determined at said comparing step.