Image sensor and operating method thereof

• US 9,313,412 B2
• Filed: 11/26/2013
• Issued: 04/12/2016
• Est. Priority Date: 11/26/2012
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: PixArt Imaging Incorporated
• Inventors: Lee, Chuan-Hsin, Yao, Wen-Han
• Primary Examiner(s): Osinski, Michael
• Application Number:
  US14/090,429
• Publication Number:
  US 20140232893A1
• Time in Patent Office: 868 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: G06T 7/246 using feature-based methods, e.g. the tracking of corners or segments
• CPC Class Codes: G06V 10/44 Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene

Abstract

There is provided an image sensor including a light sensitive device and a digital signal processing circuit. The light sensitive device is configured to output a digital image. The digital signal processing circuit is configured to detect at least one feature point in the digital image and calculate a feature point coordinate of the at least one feature point.

Claims

1. An image sensor, comprising:

a light sensitive device comprising;

a light sensing array sensing light beams impinging thereon to generate an image signal, and having an output terminal to output the image signal, and

an analog-to digital converter having an input terminal electrically coupled to the output terminal of the light sensing array for receiving the image signal, and converting the image signal into a digital image;

a memory, and

a digital signal processing circuit electrically coupled to the light sensitive device and the memory configured for

receiving the digital image from the light sensitive device,

detecting corner coordinates of at least one corner feature in the digital image for storage within the memory,

calculating a corner response value corresponding to each of the stored corner coordinates, and

sequentially scanning the digital image with a predetermined pixel range and removing, from the memory, the stored corner coordinates that do not have a maximum response value among the stored corner coordinates located within the predetermined pixel range.

2. The image sensor as claimed in claim 1, wherein the digital signal processing circuit further calculates a recognition feature of the corner feature having the maximum response value.

3. The image sensor as claimed in claim 2, wherein the digital signal processing circuit further matches the corner features having most similar recognition features in successive digital images.

4. The image sensor as claimed in claim 1, wherein the digital signal processing circuit further tracks the corner feature having the maximum response value in successive digital images.

5. The image sensor as claimed in claim 1, further comprising an image signal processing circuit electrically coupled to the light sensitive device for receiving the digital image and outputting a preview image according to the digital image.

6. The image sensor as claimed in claim 2, wherein the recognition feature comprises at least one of a rotation angle, a brightness distribution and an included angle.