Method and apparatus to capture high resolution images using low resolution sensors and optical spatial image sampling

• US 6,473,122 B1
• Filed: 12/06/1999
• Issued: 10/29/2002
• Est. Priority Date: 12/06/1999
• Status: Expired due to Fees

• Current Assignee: Hemanth G. Kanekal
• Original Assignee: Hemanth G. Kanekal
• Inventors: Kanekal, Hemanth G.
• Primary Examiner(s): Vu, Ngoc-Yen, Vu, Ngoc-Yen
• Application Number:
  US09/454,494
• Time in Patent Office: 1,058 Days
• Field of Search: H04/N.314, H04/N.5225, 348/218, 348/219, 348/302, 348/308, 348/390.1, 348/409.1, 348/415.1, 348/417.1, 348/335, 348/340
• US Class Current: 348/340
• CPC Class Codes: H04N 25/48 Increasing resolution by shifting the sensor relative to the scene

Abstract

A high-resolution digital image capturing apparatus with variable resolution capability is presented. In accordance with the present invention, the image capturing apparatus implements a motion control mechanism to incrementally move the sensor array relative to a subject. A frame of the image is captured at each incremental position. The number of frames taken is essentially limited by the distance between adjacent sensors. The frames are subsequently processed and assembled to generate a picture with improved resolution. Accordingly, the image resolution is directly related to the number of frames taken. By using the concept of fractal geometry, the number of frames required for high image resolution may be reduced thereby essentially providing a compressing technique to reduce capturing and processing time. In so doing, a digital image capturing apparatus with variable resolution capability that is inexpensive, portable, and power efficient can be achieved.

Claims

1. A digital image capturing apparatus comprising:

a CMOS-based imager circuit for capturing complete frames of image pixel data of an image object via an optical lens;

a motion control mechanism coupled to the imager circuit for incrementally repositioning the imager circuit relative to the image object to allow the imager circuit to capture different complete frames of image pixel data of the image object at different positions;

memory coupled to the imager circuit for storing frames of captured image pixel data of the image object; and

a processor coupled to the memory, the imager circuit, and the motion control mechanism for combining and processing the frames of captured image pixel data into one image thereby improving the object image resolution, wherein the imager circuit is incrementally repositioned according to a predetermined sequence designed to reduce the number of frames of captured image pixel data, wherein the reduced number of frames of captured image pixel data are independent of a physical arrangement of sensor cells of the imager circuit.

2. The digital image capturing apparatus of claim 1, wherein the predetermined repositioning sequence is based on equations derived from fractal geometry.

3. The digital image capturing apparatus of claim 1, wherein the time for frame read-out is adjustable to accommodate different data requirements.

4. The digital image capturing apparatus of claim 1, wherein the imager circuit comprises:

a CMOS-based sensor array having a plurality of sensor cells coupled to the processor, wherein each sensor cell receiving a reflected light beam from the image object thereby capturing a pixel data of the image object;

an address circuit connected to the sensor array for selectively accessing the sensor cells to retrieve captured pixel data; and

an output circuit connected to the address circuit, the memory, and to the processor for digitally processing and outputting captured pixel data to the memory.

5. The digital image capturing apparatus of claim 4, wherein the sensor cells capturing accumulated charge generated in response to reflected light beams from the image object, the sensor cells converting voltages associated with the accumulated charge into digital pixel data, the sensor cells locally storing the digital pixel data.

6. The digital image capturing apparatus of claim 5, wherein each sensor cell comprising:

a photosensor element for generating charge in response to an amount of light received;

an analog circuit connected to the photosensor element and coupled to the processor, the analog circuit generating a captured signal indicating whether the accumulated charge generated by the photosensor element reaches a ramping voltage associated with an incrementing first count value; and

a n-bit latching circuit connected to the analog circuit, the latching circuit receiving as input a second count value that is equivalent to the incrementing first count value, the latching circuit latching the second count value in response to the captured signal indicating the accumulated charge generated by the photos sensor element reaches the ramping voltage associated with the incrementing to best count value thereby generating the digital pixel data, wherein the time for frame read-out is adjustable to accommodate different data requirements.

7. The digital image capturing apparatus of claim 6, wherein the second count value is generated by a gray counter and the incrementing first count value is generated by a linear counter.

8. The digital image capturing apparatus of claim 1, wherein the motion control mechanism comprising:

a first micro-electro-mechanical device coupled to the imager circuit to move the imager circuit along a first coordinate axis thereby allowing the imager circuit to capture different complete frames of image pixel data of the image object at different positions; and

a second micro-electro-mechanical device coupled to the imager circuit to move the imager circuit along a second coordinate axis thereby allowing the imager circuit to capture different complete frames of image pixel data of the image object at different positions.

9. A digital image capturing apparatus comprising:

a CMOS-based imager circuit for capturing complete frames of image pixel data of an image object via an optical lens;

a motion control mechanism for incrementally displacing reflected light beams from the image object relative to the imager circuit to allow the imager circuit to capture different complete frames of image pixel data of the image object at different positions;

memory coupled to the imager circuit for storing frames of captured image pixel data of the image object; and

a processor coupled to the memory, the imager circuit, and the motion control mechanism for combining and processing the frames of captured image pixel data into one image thereby improving the object image resolution, wherein the reflected light beams are incrementally displaced according to a predetermined sequence designed to reduce the number of frames of captured image pixel data, wherein the reduced number of frames of captured image pixel data are independent of a physical arrangement of sensor cells of the imager circuit.

10. The digital image capturing apparatus of claim 9, wherein the predetermined displacing sequence is based on equations derived from fractal geometry.

11. The digital image capturing apparatus of claim 9, wherein the time for frame read-out is adjustable to accommodate different data requirements.

12. The digital image capturing apparatus of claim 9, wherein the imager circuit comprises:

a CMOS-based sensor array having a plurality of sensor cells coupled to the processor, wherein each sensor cell receiving a reflected light beam from the image object thereby capturing a pixel data of the image object;

an address circuit connected to the sensor array for selectively accessing the sensor cells to retrieve captured pixel data; and

an output circuit connected to the address circuit, the memory, and to the processor for digitally processing and outputting captured pixel data to the memory.

13. The digital image capturing apparatus of claim 12, wherein the sensor cells capturing accumulated charge generated in response to reflected light beams from the image object, the sensor cells converting voltages associated with the accumulated charge into digital pixel data, the sensor cells locally storing the digital pixel data.

14. The digital image capturing apparatus of claim 13, wherein each sensor cell comprising:

a photosensor element for generating charge in response to an amount of light received;

an analog circuit connected to the photosensor element and coupled to the processor, the analog circuit generating a captured signal indicating whether the accumulated charge generated by the photosensor element reaches a ramping voltage associated with an incrementing first count value; and

a n-bit latching circuit connected to the analog circuit, the latching circuit receiving as input a second count value that is equivalent to the incrementing first count value, the latching circuit latching the second count value in response to the captured signal indicating the accumulated charge generated by the photosensor element reaches the ramping voltage associated with the incrementing first count value thereby generating the digital pixel data, wherein the time for frame read-out is adjustable to accommodate different data requirements.

15. The digital image capturing apparatus of claim 14, wherein the second count value is generated by a gray counter and the incrementing first count value is generated by a linear counter.

16. The digital image capturing apparatus of claim 9, wherein the motion control mechanism comprising:

a first mirror assembly comprising a first micro-electro-mechanical actuator coupled to a first hinged mirror, the first micro-electro-mechanical actuator rotating the first hinged mirror to allow reflected light beam from the image object to be displaced along a first coordinate axis relative to the imager circuit thereby allowing the imager circuit to capture different complete frames of image pixel data of the image object at different mirror positions; and

a second mirror assembly comprising a second micro-electro-mechanical actuator coupled to a second hinged mirror, the second micro-electro-mechanical actuator rotating the second hinged mirror to allow reflected light beam from the image object to be displaced along a second coordinate axis relative to the imager circuit thereby allowing the imager circuit to capture different complete frames of image pixel data of the image object at different mirror positions.

17. A method to capture an object image comprising:

a) capturing a complete first image frame of an object using a CMOS-based photosensor array;

b) storing the first image frame;

c) incrementally repositioning the photosensor array relative to the object by a distance;

d) capturing a different complete image frame of the object;

e) storing the different image frame;

f) repeat steps (c)-(e) for a predetermined number of times, wherein the photosensor array is incrementally repositioned according to a predetermined sequence designed to reduce the number of captured image frames, wherein the reduced number of frames of captured image pixel data are independent of a physical arrangement of sensor elements of the photosensor array; and

g) combining and processing data associated with the captured images to generate a high-resolution image.

18. The method of claim 17, wherein the predetermined times are determined based on an averaged distance between two adjacent sensor elements in the photosensor array and the incremental repositioning distance.

19. The method of claim 18, wherein the predetermined sequence is based on equations derived from fractal geometry.

20. The method of claim 17, wherein the time for frame read-out is adjustable to accommodate different data requirements.

21. A method to capture an object image comprising:

a) capturing a complete first image frame of an object using a CMOS-based photosensor array;

b) storing the first image frame;

c) incrementally displacing reflected light beams from the object relative to the photosensor array by a distance;

d) capturing a different complete image frame of the object;

e) storing the different image frame;

f) repeat steps (c)-(e) for a predetermined number of times, wherein the reflected light beams are incrementally displaced according to a predetermined sequence designed to reduce the number of captured images frames, wherein the reduced number of frames of captured image pixel data are independent of a physical arrangement of sensor elements of the photosensor array; and

g) combining and processing data associated with the captured images to generate a high-resolution image.

22. The method of claim 21, wherein the predetermined times are determined based on an averaged distance between two adjacent sensor elements in the photosensor array and the incremental displacing distance.

23. The method of claim 22, wherein the predetermined sequence is based on equations derived from fractal geometry.

24. The method of claim 21, wherein the time for frame read-out is adjustable to accommodate different data requirements.