Image capture control for in vivo autonomous camera

• US 7,792,344 B2
• Filed: 08/19/2009
• Issued: 09/07/2010
• Est. Priority Date: 09/20/2005
• Status: Active Grant

• Current Assignee: CapsoVision, Inc.
• Original Assignee: CapsoVision, Inc.
• Inventors: Wu, Tong, Wang, Kang-Huai
• Primary Examiner(s): PERUNGAVOOR, SATHYANARAYA V
• Application Number:
  US12/543,508
• Publication Number:
  US 20090322865A1
• Time in Patent Office: 384 Days
• Field of Search: 382/128
• US Class Current: 382/128
• CPC Class Codes: A61B 1/00009 of image signals during a use of endoscope
• CPC Class Codes: A61B 1/00016 using wireless means
• CPC Class Codes: A61B 1/0002 provided with data storages
• CPC Class Codes: A61B 1/00029 externally powered, e.g. wireless
• CPC Class Codes: A61B 1/00032 internally powered
• CPC Class Codes: A61B 1/00036 Means for power saving, e.g. sleeping mode
• CPC Class Codes: A61B 1/041 Capsule endoscopes for imaging
• CPC Class Codes: A61B 1/0684 using light emitting diodes [LED]
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/03 Detecting, measuring or recording fluid pressure within the body other than blood pressure, e.g. cerebral pressure; Measuring pressure in body tissues or organs A61B5/205 takes precedence
• CPC Class Codes: A61B 5/073 Intestinal transmitters
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/7232 involving compression of the physiological signal, e.g. to extend the signal recording period
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 23/555 for picking-up images in sites, inaccessible due to their dimensions or hazardous conditions, e.g. endoscopes or borescopes
• CPC Class Codes: H04N 23/60 Control of cameras or camera modules

Abstract

Systems and methods are provided for motion detection and capture control of video data from a capsule camera system having an on-board storage. The capsule camera system moves through the GI tract under the action of peristalsis and records images of the intestinal walls. The capsule'"'"'s movement is episodic and jerky. The capacity of the on-board storage is limited. In order to avoid unnecessary capture of images when the capsule camera moves very slowly or stalls, motion detection technique is utilized to help control image capture. Furthermore, an adaptive capture control is disclosed that automatically adjusts the threshold level of capture control to maintain proper image capture. The invented capture control also conserves precious battery power by eliminating capture of unnecessary images when the capsule camera moves too slowly or stalls. The present invention of image capture control and threshold update is also applicable to a capsule camera system having a wireless transmitter instead of an on-board storage.

Claims

1. A capsule camera apparatus, comprising:

a housing adapted to be swallowed;

a light source within the housing;

an archival storage device;

a camera within the housing for capturing a first digital image and a second digital image of a scene illuminated by the light source;

a motion detector within the housing comprising;

a metric measurement module coupled to the first digital image and the second digital image measures a metric of a motion between the first digital image and the second digital image;

a motion detection module coupled to the metric measurement module detects the motion based on the metric and a threshold; and

a threshold update module coupled to the metric measurement module and the motion detection module updates the threshold; and

a control circuit within the housing that designates the second digital image for further processing based on the motion detected by the motion detection module.

2. A capsule camera apparatus as in claim 1, wherein a portion of the first digital image is stored in a first partial frame buffer and a portion of the second digital image is stored in a second partial frame buffer.

3. A capsule camera apparatus as in claim 2, wherein the control circuit determines which of the first and second partial frame buffers is to be overwritten by a third digital image according to the motion detected.

4. A capsule camera apparatus as in claim 1, further comprising a register for storing the metric, the register being accessible by the motion detector and/or the threshold update module during operation.

5. A capsule camera apparatus as in claim 1, wherein the metric measurement module evaluates zero-valued motion vectors between a portion of the first digital image and a portion of the second digital image.

6. A capsule camera apparatus as in claim 5, wherein the metric includes a value related to a count of zero-valued motion vectors.

7. A capsule camera apparatus as in claim 1, wherein the metric measurement module computes average absolute differences between corresponding portions of the first digital image and the second digital image.

8. A capsule camera apparatus as in claim 7, wherein the metric includes a variance of the average absolute differences.

9. A capsule camera apparatus as in claim 1, wherein the metric measurement module computes for a portion of the first digital image and a portion of the second digital image each a center-of-mass.

10. A capsule camera apparatus as in claim 9, wherein the metric depends on a difference between the centers-of-mass computed.

11. A capsule camera apparatus as in claim 1, wherein the control circuit causes a new second digital image to be captured according to the metric and the threshold.

12. A capsule camera apparatus as in claim 11, further comprising a register for storing a result of the control circuit as being captured or skipped, wherein the register being accessible by the motion detector and/or the threshold update module.

13. A capsule camera apparatus as in claim 12, wherein a number of images skipped between two captured images is counted, an initial value of an average number of skipped images is provided, and the average number of skipped images is updated according to function of a plurality of previous values of the average number of skipped images and a current value of the number of skipped images.

14. A capsule camera apparatus as in claim 13, wherein the function is a linear function having weighting factors.

15. A capsule camera apparatus as in claim 14, wherein the weighting factors have more weight on more recent previous values of the average number of skipped images.

16. A capsule camera apparatus as in claim 13, wherein the threshold is increased if the average number of skipped images is smaller than a low limit and the threshold is smaller than a maximum threshold.

17. A capsule camera apparatus as in claim 13, wherein the threshold is decreased if the average number of skipped images is larger than a high limit and the threshold is larger than a minimum threshold.

18. A method for capsule camera, comprising:

providing a housing adapted to be swallowed;

providing a light source and a camera within the housing;

providing an archival storage device;

capturing a first digital image and a second digital image of a scene illuminated by the light source;

measuring a metric of motion between the first digital image and the second digital image;

detecting a motion based on the metric and a threshold;

updating the threshold; and

designating the second digital image for further processing based on the motion detected,

wherein the measuring, detecting, updating and designating steps are performed by circuitry within the housing.

19. A method as in claim 18, wherein a portion of the first digital image is stored in a first partial frame buffer and a portion of the second digital image is stored in a second partial frame buffer.

20. A method as in claim 18, wherein said measuring the metric includes zero-valued motion vectors between a portion of the first digital image and a portion of the second digital image.

21. A method as in claim 20, wherein the metric has a value related to a count of zero-valued motion vectors.

22. A method as in claim 18, wherein said measuring the metric includes computing average absolute differences between corresponding portions of the first digital image and the second digital image.

23. A method as in claim 22, wherein the metric is related to a variance of the average absolute differences.

24. A method as in claim 18, wherein said measuring the metric includes computing for a portion of the first digital image and a portion of the second digital image each a center-of-mass.

25. A method as in claim 24, wherein the metric is related to a difference between the centers-of-mass computed.

26. A method as in claim 18, wherein the further processing includes causing a new second digital image to be captured.

27. A method as in claim 26, further comprising a register for storing a result of the further processing as being captured or skipped, wherein the register being accessible by said detecting the motion.

28. A method as in claim 27, wherein a number of images skipped between two captured images is counted, an initial value of an average number of skipped images is provided, and the average number of skipped images is updated according to a function of a plurality of previous values of the average number of skipped images and a current value of the number of skipped images.

29. A method as in claim 28, wherein the function is a linear function having weighting factors.

30. A method as in claim 29, wherein the weighting factors have more weight on more recent previous values of the average number of skipped images.

31. A method as in claim 28, wherein the threshold is increased if the average number of skipped images is smaller than a low limit and the threshold is smaller than a maximum threshold.

32. A method as in claim 28, wherein the threshold is decreased if the average number of skipped images is larger than a high limit and the threshold is larger than a minimum threshold.

33. A capsule camera apparatus, comprising:

a housing adapted to be swallowed;

a light source within the housing;

a camera within the housing for capturing a first digital image and a second digital image of a scene illuminated by the light source;

a motion detector within the housing comprising;

a metric measurement module coupled to the first digital image and the second digital image measures a metric of a motion between the first digital image and the second digital image;

a motion detection module coupled to the metric measurement module detects the motion based on the metric and a threshold; and

a threshold update module coupled to the metric measurement module and the motion detection module updates the threshold;

a wireless transmitter within the housing coupled to transmit the second digital image; and

a control circuit within the housing that designates the second digital image for transmission via the wireless transmitter based on the motion detected by the motion detection module.

34. A capsule camera apparatus, comprising:

a housing adapted to be swallowed;

a light source within the housing;

a light control circuitry coupled to the light source to provide light control signal;

an archival storage device;

a camera within the housing for capturing a first digital image and a second digital image of a scene illuminated by the light source;

a motion detector within the housing comprising;

a metric measurement module coupled to the first digital image and the second digital image measures a metric of a motion between the first digital image and the second digital image;

a motion detection module coupled to the metric measurement module detects the motion based on the metric and a threshold; and

a threshold update module coupled to the metric measurement module and the motion detection module updates the threshold, wherein the threshold updating is related to the light control signal; and

a control circuit within the housing that designates the second digital image for further processing based on the motion detected by the motion detection module.

35. A capsule camera apparatus, comprising:

a housing adapted to be swallowed;

a light source within the housing;

a light control circuitry coupled to the light source to provide light control signal;

a camera within the housing for capturing a first digital image and a second digital image of a scene illuminated by the light source;

a motion detector within the housing comprising;

a metric measurement module coupled to the first digital image and the second digital image measures a metric of a motion between the first digital image and the second digital image;

a motion detection module coupled to the metric measurement module detects the motion based on the metric and a threshold; and

a threshold update module coupled to the metric measurement module and the motion detection module updates the threshold, wherein the threshold updating is related to the light control signal; and

a wireless transmitter within the housing coupled to transmit the second digital image; and

a control circuit within the housing that designates the second digital image for transmission via the wireless transmitter based on the motion detected by the motion detection module.