Method and apparatus for tracking image patch considering scale

• US 8,903,159 B2
• Filed: 04/21/2010
• Issued: 12/02/2014
• Est. Priority Date: 10/09/2009
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Choi, Ki-wan, Lee, Hyoung-ki, Park, Ji-young
• Primary Examiner(s): Vu, Kim
• Assistant Examiner(s): HU, FRED H.
• Application Number:
  US12/662,528
• Publication Number:
  US 20110085699A1
• Time in Patent Office: 1,686 Days
• Field of Search: None
• US Class Current: 382/153
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 7/248 involving reference images or patches

Abstract

A method and apparatus for tracking an image considering scale are provided. A registered image patch may be divided into a scale-invariant image patch and a scale-variant image patch according to a predetermined scale invariance index (SII). If a registered image patch within an image is a scale-invariant image patch, the scale-invariant image patch is tracked by adjusting its position, while if the registered image patch is a scale-variant image patch, the scale-invariant image patch is tracked by adjusting its position and scale.

Claims

1. An image patch tracker, including one or more processing devices, the image patch tracker comprising:

a scale invariance index (SII) calculating unit including at least one of the one or more processing devices to calculate an SII based on a pixel value change with respect to a scale change for a registered image patch; and

a scale characteristic deciding unit including at least one of the one or more processing devices to compare the SII to a threshold and to selectively determine the registered image patch to be one of a scale-invariant image patch, when the SII is less than the threshold, and a scale-variant image patch, when the SII is not less than the threshold.

2. The image patch tracker of claim 1, wherein the pixel value change with respect to the scale change varies depending on respective positions of scale reference points, defined as respective reference points for scale-up or scale-down of the registered image patch, and the SII is defined as a least mean square of the pixel value change for each of the scale reference points.

3. The image patch tracker of claim 2, wherein the SII calculating unit sets at least one of the scale reference points within the registered image patch, calculates a mean of squared pixel value change with respect to the scale change for each of the scale reference points, and selects a least of the calculated results of the calculated mean of squared pixel value change as the SII.

4. The image patch tracker of claim 1, further comprising an image patch tracking unit to adjust a position of the registered image patch to track the registered image patch within a received image when the registered image patch is determined to be the scale-invariant image patch, and adjusting a position and size of the registered image patch to track the registered image patch within a received image when the registered image patch is determined as the scale-variant image patch.

9. The image patch tracker of claim 1, wherein the SIII calculation unit calculates the SII based on a scale change for a shape of the registered image patch.

10. The image patch tracker of claim 9, further comprising an image patch tracking unit to adjust a position and shape of the registered image patch to track the registered image patch within a received image when the registered image patch is determined as the scale-variant image patch.

11. The image patch tracker of claim 1, further comprising an image patch tracking unit to adjust a position and shape of the registered image patch to track the registered image patch within a received image when the registered image patch is determined as the scale-variant image patch.

5. A method of tracking an image patch considering scale, comprising:

calculating a scale invariance index (SII) based on a pixel value change with respect to a scale change for a registered image patch; and

comparing the SII to a threshold and selectively determining the registered image patch to be one of a scale-invariant image patch, when the SII is less than the threshold, and a scale-variant image patch, when the SII is not less than the threshold.

6. The method of claim 5, wherein the pixel value change with respect to the scale change varies depending on respective positions of scale reference points, defined as respective reference points for scale-up or scale-down of the registered image patch, and the SII is defined as a least mean square of the pixel value change for each of the scale reference points.

7. The method of claim 6, wherein calculating the SII comprises:

setting at least one of the scale reference points within the registered image patch; and

calculating a mean of squared pixel value change with respect to the scale change for each of the scale reference points and selecting a least of the calculated results of the calculated mean of squared pixel value change as the SII.

8. The method of claim 5, further comprising:

adjusting a position of the registered image patch to track the registered image patch within a received image when the registered image patch is determined to be the scale-invariant image patch; and

adjusting a position and size of the registered image patch to track the registered image patch within a received image when the registered image patch is determined to be the scale-variant image patch.

12. The method of claim 5, further comprising calculating the SII based on a scale change for a shape of the registered image patch.

13. The method of claim 12, further comprising an image patch tracking unit to adjust a position and shape of the registered image patch to track the registered image patch within a received image when the registered image patch is determined as the scale-variant image patch.

14. The method of claim 5, further comprising an image patch tracking unit to adjust a position and shape of the registered image patch to track the registered image patch within a received image when the registered image patch is determined as the scale-variant image patch.