Inter-Frame Motion Detection

• US 20100303301A1
• Filed: 06/01/2009
• Published: 12/02/2010
• Est. Priority Date: 06/01/2009
• Status: Abandoned Application

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Lamoureux, Gregory Micheal
• Application Number:
  US12/475,832
• Publication Number:
  US 20100303301A1
• Time in Patent Office: Days
• US Class Current: 382/107
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G06T 7/254 involving subtraction of images

Abstract

Methods and systems for detecting motion depicted in a sequence of frames are disclosed. One example method includes estimating a direction and a velocity of the depicted motion. Estimating the velocity includes evaluating velocities in a first range of velocities and evaluating velocities in a second range of velocities if a sufficiently reliable velocity estimate is not found in the first range of velocities.

Claims

1. A method for detecting motion depicted in a sequence of frames, the method comprising:

estimating a direction and a velocity of the depicted motion,

wherein estimating the motion velocity includes;

evaluating velocities in a first range of velocities; and

evaluating velocities in a second range of velocities if a sufficiently reliable velocity estimate is not found in the first range of velocities.

2. The method as recited in claim 1, wherein the first range overlaps at least partially with the second range.

3. The method as recited in claim 2, further comprising:

evaluating velocities in the second range of velocities if a most reliable velocity found in the first range is within a portion of the first range that overlaps with the second range.

4. The method as recited in claim 1, wherein a velocity estimate is determined to be sufficiently reliable based on whether a reliability measure of the velocity estimate meets a threshold.

5. The method as recited in claim 4, wherein the reliability measure is calculating by summing a number of differences between a first block of pixels of a first frame image and a second block of pixels of a second frame image, the second region being spatially shifted with respect to the first region by a magnitude derived from the velocity estimate.

6. The method as recited in claim 1, wherein a velocity estimate is determined not to be sufficiently reliable if the velocity estimate is within a portion of the first range that overlaps with the second range.

7. The method as recited in claim 1, wherein estimating the motion velocity further includes evaluating velocities in a third range of velocities if a sufficiently reliable velocity estimate is not found in the second range of velocities.

8. A method for detecting motion depicted in a sequence of frames, the method comprising:

identifying one or more motion sections in the sequence of frames; and

for each of the one or more motion sections, identifying a motion velocity,

wherein identifying the motion velocity includes calculating a reliability measure for each of a plurality of candidate motion velocities.

9. The method of claim 8, wherein the one or more motion sections are identified by comparing consecutive frames in the sequence of frames.

10. The method of claim 8, wherein identifying the motion velocity further includes:

comparing a first region of a first frame image with a second region of a second frame image, the second region being displaced by a number of pixels corresponding to one of the candidate motion velocities,

wherein calculating the reliability measure of the candidate motion velocity includes determining a degree to which the first region matches the second region.

11. The method of claim 8, wherein the candidate motion velocities lie within a first range and wherein identifying the motion velocity includes:

identifying a most reliable candidate motion velocity in the first range based on reliability measures associated with each candidate motion velocity in the first range.

12. The method of claim 11, wherein identifying the motion velocity further includes:

evaluating the reliability measures of the motion velocities in the first range to determine whether the most reliable candidate motion velocity in the first range is sufficiently reliable; and

evaluating a second range of candidate motion velocities if the most reliable candidate motion velocity in the first range is not sufficiently reliable.

13. The method of claim 8, further comprising:

identifying a direction of motion for the one or more motion sections; and

changing the identified direction based on the reliability measures of the candidate motion velocities.

14. The method of claim 13, wherein the identified direction is changed if a most reliable one of the candidate motion velocities does not meet a reliability threshold.

15. The method of claim 14, further comprising:

identifying subsections in at least one section,

wherein calculating a reliability measure for each of a plurality of candidate motion velocities includes;

calculating reliability measures for the candidate motion velocities using a first one of the subsections and the identified direction; and

calculating reliability measures for the candidate motion velocities using a second one of the subsections and the identified direction, and

wherein the identified direction is changed if an average of a most reliable one of the reliability measures calculated using the first subsection and a most reliable one of the reliability measures calculated using the second subsection does not meet a reliability threshold.

16. The method of claim 8, further comprising:

converting at least a portion of the frames into bitonal images; and

identifying the plurality of motion sections using the bitonal images.

17. A method for detecting motion depicted in a sequence of frames, the method comprising:

comparing a first pixel of a first frame in the sequence with a second pixel of a second frame in the sequence, the first and second pixels having corresponding locations in their respective frames;

comparing the first and second pixels to identify the pixels as either foreground pixels or background pixels; and

using the pixels to characterize a motion depicted by the sequence of frames if the pixels are identified as foreground pixels.

18. The method of claim 17, further comprising:

converting the first and second pixels to bitonal pixels,

wherein comparing the first and second pixels includes comparing pixel intensities of the first and second bitonal pixels and identifying the pixels as foreground pixels if the pixel intensities differ.

19. One or more computer-readable media having computer-readable instructions thereon which, when executed, implement a method for detecting motion depicted in a sequence of frames, the method comprising the acts of:

estimating a direction of the depicted motion; and

estimating a velocity of the depicted motion,

wherein estimating the motion velocity includes;

evaluating velocities in a first range of velocities; and

evaluating velocities in a second range of velocities if a sufficiently reliable velocity estimate is not found in the first range of velocities.

20. A system for processing a sequence of frames based on motion detected in the frames, the system comprising:

a memory buffer configured to receive a plurality of frames;

a processing circuit configured to carry out the following acts;

estimating a direction of motion depicted in the frames;

estimating a velocity of the depicted motion,

wherein estimating the velocity of motion includes;

evaluating velocities in a first range of velocities; and

evaluating velocities in a second range of velocities if a sufficiently reliable velocity estimate is not found in the first range of velocities.

21. The system as recited in claim 20, wherein the processing circuit is further configured to modify the plurality of frames to minimize a perceived blur based on the estimated motion velocity and direction.