System and method for generating a rolled surface representation from a set of partial images

• US 6,597,802 B1
• Filed: 08/25/1999
• Issued: 07/22/2003
• Est. Priority Date: 08/13/1999
• Status: Expired due to Term

• Current Assignee: Uniloc 2017 LLC (SoftBank Group Corp.)
• Original Assignee: International Business Machines Corporation
• Inventors: Ratha, Nalini Kanta, Connell, Jonathan Hudson, Bolle, Rudolf Maarten
• Primary Examiner(s): CHANG, JON CARLTON
• Application Number:
  US09/382,732
• Time in Patent Office: 1,427 Days
• Field of Search: 382/124,284,125,126,127 345/629 40/5.53,5.83 396/15
• US Class Current: 382/124
• CPC Class Codes: G06V 40/1335 Combining adjacent partial images (e.g. slices) to create a composite input or reference pattern; Tracking a sweeping finger movement

Abstract

The invention is a system and method for constructing a rolled surface image from a set of partial surface images. A sequence of individual partial surface images is acquired as an object is progressively rolled across the surface of an imaging device. The imaging device is configured so that only that part of the object'"'"'s surface which is in close proximity is imaged. To produce a complete rolled surface image, i.e. a composite image, the value of each pixel of the composite image is derived by performing a suitable pixel operation on the set of corresponding pixels in the input partial surface images. This is possible because each partial image is represented as a fixed size and each pixel in each of the partial images has a unique position in the partial image. The system can also directly produce a list of salient surface features. Localized features are extracted from each individual partial image whereas other specific attributes of each image are ignored. The features from different partial surface images are then matched up to generate clusters of observations associated with each unique surface feature. These clusters are analyzed to produce more accurate positional information as well as a confidence measure for each observed feature in the complete set covering the rolled surface of the object.

Claims

1. A system for generating an extended surface image of an object having one or more convex surfaces, each of the convex surfaces having a characteristic radius and one or more physical textures, the system comprising:

an imaging device that acquires a plurality of partial surface images of the object, each of the partial surface images having a fixed size and including a fixed number of pixels, each partial surface image being of the part of the object adjacent, within a tolerance, to the surface of the imaging device, each partial surface image having an image position for each pixel, and the object being continuously rolled with respect to the imaging device so that each part of the partial surface of the object is associated with a respective image pixel position; and

a view integration system combining each pixel at the respective image pixel position, such that all of the partial surface images merge.

2. A system, as in claim 1, where the object being imaged is a human finger.

3. A system, as in claim 1, where the object being imaged is a rigid cylindrical container.

4. A system, as in claim 1, where the imaging device is an optical camera.

5. A system, as in claim 1, where the imaging device is an ultrasound sensor.

6. A system, as in claim 1, where the imaging device is an electronic capacitive sensor.

7. A system, as in claim 1, where the imaging device is a thermal sensor.

8. A system, as in claim 1, where the tolerance is determined by a frustrated total internal reflection-based live scan fingerprint sensor.

9. A system, as in claim 1, where the tolerance is less than 10% of the characteristic radius of each of the object'"'"'s convex surfaces.

10. A system, as in claim 1, where the pixel combining is done by taking the smallest pixel value of all pixel values at the respective image position.

11. A system, as in claim 1, where the pixel combining is done by taking the largest pixel value of all pixel values at the respective image position.

12. A system, as in claim 1, where the view integration process determines a histogram of the pixel values at each image position and uses this to derive an output value.

13. A system, as in claim 12, where the view integration process approximates the pixel value histogram by a sum of several Gaussian distributions and the mean value of one of the resulting Gaussian distribution is outputted.

14. A system, as in claim 1, where each partial surface images are not stored but are merged as soon as the partial surface image is available.

15. A system, as in claim 1, where the partial surface images are acquired until a stop condition is met.

16. A system, as in claim 15, where the stop condition is one or more of the following:

a number of frames processed, time taken for acquiring said partial surface images and a signal generated by a human observer.

17. A system, as in claim 1, wherein continuously rolling the object with respect to the imaging device is effected by holding the object stationary and rolling the imaging device around the object to acquire the partial surface images.

18. A system for generating an extended surface image of an object having one or more convex surfaces, each of the convex surfaces having a characteristic radius and one or more physical textures, the system comprising:

an imaging device that acquires a plurality of partial surface images of the object, each of the partial surface images having a fixed size and including a fixed number of pixels, each partial surface image being of the part of the object adjacent, within a tolerance, to the surface of the imaging device, each partial surface image having an image position for each pixel, and the object being continuously rolled with respect to the imaging device so that each part of the partial surface of the object is associated with a respective image pixel position, wherein said tolerance is determined by an illumination source producing a limited thickness sheet of light substantially parallel to the surface of the imaging device; and

a view integration system combining each pixel at the respective image pixel position, such that all of the partial surface images merge.

19. A system for generating an extended surface image of an object having one or more convex surfaces, each of the convex surfaces having a characteristic radius and one or more physical textures, the system comprising:

an imaging device that acquires a plurality of partial surface images of the object until reaching a stop condition, each of the partial surface images having a fixed size and including a fixed number of pixels, each partial surface image being of the part of the object adjacent, within a tolerance, to the surface of the imaging device, each partial surface image having an image position for each pixel, and the object being continuously rolled with respect to the imaging device so that each part of the partial surface of the object is associated with a respective image pixel position, said stop condition being based on one or more of the following characteristics of the extended surface image;

a pixel average gray value, a bounding box of pixels below an intensity threshold, and mathematical moments of pixel values; and

a view integration system combining each pixel at the respective image pixel position, such that all of the partial surface images merge.