METHOD AND APPARATUS FOR SENSOR CHARACTERIZATION

• US 20100165158A1
• Filed: 12/21/2009
• Published: 07/01/2010
• Est. Priority Date: 12/26/2008
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B.
• Granted Patent: US 9,544,516 B2
• Time in Patent Office: Days
• US Class Current: 348/294
• CPC Class Codes: H04N 1/00002 Diagnosis, testing or measuring; Detecting, analysing or monitoring not otherwise provided for error detection, error correction or monitoring in digital computers or digital computer components G06F11/00
• CPC Class Codes: H04N 1/00013 Reading apparatus
• CPC Class Codes: H04N 1/00031 Testing, i.e. determining the result of a trial H04N1/00029 takes precedence; using test signals for transmission mode changing H04N2201/33371
• CPC Class Codes: H04N 1/00047 using an image not specifically designed for the purpose
• CPC Class Codes: H04N 1/0005 in service, i.e. during normal operation
• CPC Class Codes: H04N 1/00063 using at least a part of the apparatus itself, e.g. self-testing
• CPC Class Codes: H04N 1/00068 Calculating or estimating
• CPC Class Codes: H04N 1/00076 locally
• CPC Class Codes: H04N 1/00087 Setting or calibrating picture signal circuits H04N1/40
• CPC Class Codes: H04N 1/0009 Storage
• CPC Class Codes: H04N 1/00307 with a mobile telephone apparatus constructional features of portable telephone sets H04M1/0202; mobile radio systems H04W84/00
• CPC Class Codes: H04N 1/32149 Methods relating to embedding, encoding, decoding, detection or retrieval operations
• CPC Class Codes: H04N 1/401 Compensating positionally unequal response of the pick-up or reproducing head H04N1/403 takes precedence
• CPC Class Codes: H04N 25/67 applied to fixed-pattern noise, e.g. non-uniformity of response

Abstract

The detailed technology relates to optical sensors, and more particularly relates to characterizing local behaviors of a sensor, and using such characterization information in a sensor-based system. In a particular arrangement, output signals produced from each of plural sensing elements in a 2D optical sensor are checked to determine whether they tend to differ from output signals produced by one or more neighboring sensing elements—when combined across plural captured image frames. The results are stored in an associated memory, and can be consulted in determining how image data captured from the sensor should be used. The technology is particularly illustrated in the context of a watermark decoder for a cell phone camera. A variety of other features and arrangements are also detailed.

Claims

1. A method involving an optical sensor, the sensor comprising plural optical sensing elements, each producing an output signal, the method comprising the acts:

capturing plural frames of image data using the optical sensor;

for each of plural sensing elements in the optical sensor, determining whether output signals produced therefrom tend to differ from output signals produced by one or more neighboring sensing elements, when said signals are combined across the plural captured frames; and

storing results from said determination in a memory associated with the optical sensor.

2. The method of claim 1 that further includes using the sensor to capture a further frame of image data, and processing the further frame of image data using information from the memory.

3. The method of claim 2 that further includes adjusting values in the further frame of image data to counteract biases indicated by the information from the memory.

4. The method of claim 2 that further includes decoding a steganographically-encoded watermark signal from the further frame of image data, wherein the decoding includes disregarding certain values based on information from the memory.

5. The method of claim 2 that further includes decoding a steganographically-encoded watermark signal from the further frame of image data, wherein the decoding includes weighting votes in accordance with information from the memory.

6. The method of claim 1 that includes combining signals from the neighboring sensing elements across the plural captured frames by averaging.

7. The method of claim 1 that includes, for each of plural sensing elements in the optical sensor, determining whether output signals produced therefrom tend to differ from output signals produced by two or more neighboring sensing elements, when said signals are combined across the plural captured frames.

8. An apparatus comprising:

an optical sensor including plural optical sensing elements;

a memory, the memory having data stored therein about biases of plural sensing elements relative to neighboring sensing elements.

9. The apparatus of claim 8 wherein the sensor and the memory are formed on a common semiconductor substrate.

10. The apparatus of claim 8, further including a processor that is operatively connected to the optical sensor and to the memory, to process output signals from the optical sensor in accordance with the data about biases of sensing elements stored in the memory.

11. The apparatus of claim 8 further including a steganographic watermark decoder that receives output signals processed by the processor, and decodes digital watermark data therefrom.

12. The apparatus of claim 11, wherein the processor is operative to disregard certain output signals from the sensor in accordance with the memory data about the sensor elements.

13. A method comprising the acts:

capturing visual information from a physical object using an array of sensor elements, yielding visual data; and

transforming the visual data by reference to stored data indicating behavior of at least certain of said sensor elements relative to neighboring sensor elements.

14. The method of claim 13 in which the transforming includes adjusting values of certain of the visual data in accordance with the stored data.

15. The method of claim 13 in which the transforming includes disregarding certain of the visual data in accordance with the stored data.

16. The method of claim 13 that includes decoding steganographically encoded watermark data from the transformed visual data.