Resolution enhancement by multiple scanning with a low-resolution, two-dimensional sensor array

• US 6,005,682 A
• Filed: 06/07/1995
• Issued: 12/21/1999
• Est. Priority Date: 06/07/1995
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Wu, Xiaodong, Weisfield, Richard, Anderson, Harold M., Castelli, Vittorio, Street, Robert A., Connell, G. A. Neville
• Primary Examiner(s): Rogers, Scott
• Assistant Examiner(s): BRINICH, STEPHEN M
• Application Number:
  US08/485,847
• Time in Patent Office: 1,658 Days
• Field of Search: 358/486, 358/493, 358/494, 358/496, 358/497, 358/474, 358/482, 358/483, 359/201, 359/202, 359/203, 359/211, 250/208.1, 250/234, 250/235
• US Class Current: 358/474
• CPC Class Codes: H04N 1/1911 Simultaneously or substantially simultaneously scanning picture elements on more than one main scanning line, e.g. scanning in swaths
• CPC Class Codes: H04N 1/19505 Scanning picture elements spaced apart from one another in at least one direction
• CPC Class Codes: H04N 1/19515 in two directions
• CPC Class Codes: H04N 1/19531 Reflecting elements
• CPC Class Codes: H04N 1/19536 Refracting elements
• CPC Class Codes: H04N 1/19563 about an axis perpendicular to the optical axis
• CPC Class Codes: H04N 1/19589 Optical means, e.g. an optical fibre bundle, for mapping the whole or a part of a scanned image onto the array
• CPC Class Codes: H04N 25/48 Increasing resolution by shifting the sensor relative to the scene

Abstract

The system achieves high-resolution imaging with low-resolution two-dimensional imagers whose sensors are only a fraction of a selected pixel area. Sensors are stepped across an image with an optical or mechanical stepper to acquire an image at each sensor position. Thereby, resolution is defined by a step size which is comparable to the sensor size, rather than by pixel resolution. The system thus uses multiple image, obtained from individual sensors, which have a sensed area substantially less than the area of the pixels of the sensor array. Such rescanning is accomplished by movable mirrors or lenses that are disposed between an illuminated specimen and a sensor area.

Claims

1. An enhanced resolution image scanner for generating a data signal representative of an image of an associated specimen wherein the data signal has a resolution greater than a resolution of a sensor array of the scanner, comprising:

an array of sensors wherein said sensors are relatively spaced by an interstice and disposed to generate a signal representative of a first subportion of a selected pixel of the associated specimen during a first scan, each said selected pixel having an area greater than said first subportion, and

orientation means interposed between the specimen and the array for reorienting each of the sensors relative to the data signal of the associated specimen during a second scan for displacing the data signal as an undivided signal and generating a second signal representative of at least a second subportion of the selected pixel comprising an area of said specimen missed by the scanner array due to said interstice.

2. The enhanced resolution image scanner of claim 1 wherein the orientation means includes:

directing means for redirecting the image of the specimen relative to each of the sensors for generating the second signal therefrom with the second subportion comprising a different part of the selected pixel.

3. The enhanced resolution image scanner of claim 1 wherein the orientation means includes:

directing means for redirecting the image of the specimen relative to each of the sensors for generating the second signal relative to a different chrominant content of the selected pixel.

4. The enhanced resolution image scanner of claim 2 wherein the directing means is comprised of first and second rotating translucent wedges having a common optical axis disposed between pixels of the associated specimen and the sensor array;

and wherein the image scanner further comprises,

a first lens, sharing the common optical axis, disposed between the rotating translucent wedges and the associated specimen; and

a second lens, sharing the common optical axis, disposed between the rotating translucent wedges and the sensor array.

5. The enhanced resolution image scanner of claim 4 further comprising a motor rotating the first rotating translucent wedge at a first angular velocity and the second rotating translucent wedge at a second angular velocity different from the first angular velocity.

6. The enhanced resolution image scanner of claim 2 wherein the directing means is comprised of:

first and second rotating mirrors disposed in an optical path between pixels of the associated specimen and the sensor array;

a first lens disposed to focus light from the associated specimen to the first rotating mirror; and

a second lens disposed to focus light from the second rotating mirror to the sensor array.

7. The enhanced resolution image scanner of claim 6 further comprising a motor rotating the first rotating mirror at a first angular velocity and the second rotating mirror at a second angular velocity different from the first angular velocity.

8. The enhanced resolution image scanner of claim 2 wherein:

the directing means comprises a stepper for obtaining the second signal from a linearly displaced position along the associated specimen relative to a position generating the data signal of the first subportion of the selected pixel; and

the stepper comprises a mechanical translator for selectively translating the image of the associated specimen relative to the sensor array.

9. The enhanced resolution scanner of claim 8 wherein the stepper comprises:

a first mirror;

a first lens for directing light reflected from the associated specimen to the first mirror;

a second lens;

a second mirror disposed to receive receiving light reflected from the first mirror for reflecting the light to the second lens;

the second lens focussing the light to the sensor array; and

a translator pivoting at least one of the first and second mirrors on a selected axis to the displaced position.

10. The enhanced resolution image scanner of claim 9 wherein the stepper further comprises:

a projection lens for projecting an image of an associated specimen on to the sensor array; and

a translator for displacing the projection lens laterally to the displaced position.

11. The enhanced resolution scanner of claim 3 wherein the orientation means further includes means for generating the second signal by selectively undersampling an enhancement content of the selected pixel of the associated specimen.

12. The enhanced resolution scanner of claim 1 wherein each sensor of the array has a selected orientation relative to each selected pixel such that the second signal is acquired by linearly displacing the sensor array relative to the specimen via the orientation means.

13. The enhanced resolution scanner of claim 12 wherein the linearly displacing is parallel to a linear array of the array of sensors.

14. The enhanced resolution scanner of claim 12 wherein the linearly displacing is at an angle relative to a linear array of the array of sensors.

15. The enhanced resolution scanner of claim 14 wherein the angle is chosen as generally 45°

.

16. A method of obtaining enhanced scanned image data of a specimen comprising the steps of:

illuminating the specimen;

directing light from the illuminated specimen to a sensor array comprising a plurality of spaced sensor elements, wherein a first portion of a pixel of the specimen can be detected by the sensor elements;

selectively orienting the sensor elements relative to the associated specimen via a light director interposed between the specimen and the array;

generating a first signal representative of the first portion of the illuminated specimen by directing the light from the first portion on to the sensor array;

reorienting the sensor array relative to the specimen by redirecting the light as an undivided signal to the sensor array from a second portion comprising a portion of the specimen missed by the sensor array due to spacings of the spaced sensor elements; and

generating a second signal representative of the second portion of the second pixel on the illuminated specimen.

17. The method of claim 16 wherein:

the step of selectively orienting further includes rotating first and second translucent wedges having a common optical axis disposed between the associated specimen and the sensor array wherein the rotating of the first translucent wedge is at a first angular velocity and the rotating of the second translucent wedge is at a second angular velocity different from the first angular velocity.

18. The method of claim 16 wherein the step of selectively orienting further includes:

rotating first and second mirrors having a common optical path disposed between the associated specimen and the sensor array wherein rotating the first mirror is at a first angular velocity and rotating the second mirror is at a second angular velocity different from the first angular velocity.

19. The method of claim 16 wherein the step of selectively orienting includes the steps of:

directing light reflected from the associated specimen to a first mirror;

receiving the light reflected from the first mirror to a second mirror from and reflecting the light to a second lens;

focussing the light reflected from the second mirror through the second lens to the sensor array; and

pivoting at least one of the first and second mirrors on a selected axis to provide the second portion.

20. The method of claim 16 wherein the step of selectively orienting includes the steps of:

projecting, through a projection lens, an associated specimen on to the sensor array; and

displacing, through a translator, the projection lens laterally to provide the second portion.

21. An enhanced resolution image scanner comprising:

an array of sensors, each sensor of the array adapted to generate a signal representative of a first subportion of a selected pixel of an associated specimen;

orientation means for selectively orienting each of the sensors relative to the associated specimen so as to generate a second signal representative of at least a second, unique subportion of each selected pixel in accordance with the relation;

space="preserve" listing-type="equation">x=A sin(2π

f.sub.1 t)+B sin (2π

f.sub.2 +Φ

); and

space="preserve" listing-type="equation">y=A cos(2π

f.sub.1 t)+B cos (2f.sub.d +Φ

); and

wherein A and B represent amplitudes of trajectory and displacement and wherein f₁ and f₂ are the effective rotation frequencies of the sensors and the associated specimen, respectively;

wherein a section of parameters A, B, Φ

, f₁ and f₂ are such that the trajectory of the sensor position overlap to a pixel grid that has an enhanced resolution.

22. The enhanced resolution image scanner of claim 21 wherein the stepper is comprised of a mechanical translator for selectively translating the sensor array relative to the associated specimen, the orientation means including at least one of:

means for rotating at least one translucent wedge disposed in an optical path between the sensor array and the specimen; and

means for rotating at least one mirror disposed in an optical path between the sensor array and the specimen.

23. The enhanced resolution image scanner of claim 22 wherein the stepper includes means for directing each of the sensors relative to the associated specimen to a next pixel displaced linearly adjacent to the selected pixel.