Image compensation method with correctional gray level values of complete black and/or white

• US 8,194,290 B2
• Filed: 09/15/2003
• Issued: 06/05/2012
• Est. Priority Date: 10/30/2002
• Status: Active Grant

• Current Assignee: Intellectual Ventures I LLC (Intellectual Ventures LLC)
• Original Assignee: Transpacific Systems LLC (Intellectual Ventures LLC)
• Inventors: Kuo, Shih-Zheng
• Primary Examiner(s): KAU, STEVEN Y
• Application Number:
  US10/662,258
• Publication Number:
  US 20040085594A1
• Time in Patent Office: 3,186 Days
• Field of Search: 358/3.01, 358/2.1, 358/3.03, 358/406, 358/474, 358/1.9, 358/3.02, 358/505, 358/506, 358/408, 358/487, 358/496, 358/3.06, 382/251, 382/169, 382/237, 382/167, 382/149, 382/141, 382/154, 382/175, 382/266, 382/274, 382/318, 348/254, 348/518, 348/671, 348/747, 348/E5.034, 348/E5.036, 347/41, 347/15, 347/79, 347/233, 347/235, 347/250
• US Class Current: 358/474
• 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 1/00045 using a reference pattern designed for the purpose, e.g. a test chart
• 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 1/00087 Setting or calibrating picture signal circuits H04N1/40
• CPC Class Codes: H04N 1/1017 the main-scanning components remaining positionally invariant with respect to one another in the sub-scanning direction
• CPC Class Codes: H04N 1/193 using electrically scanned linear arrays , e.g. linear CCD arrays

Abstract

An image compensating method. First, multiple scanning lines are used to scan a document and a longitudinal black and white pattern, in order to produce the actual gray level value for multiple pixels with respect to each of the scanning lines and the document, as well as a correctional gray level value for complete black and a correctional gray level value for complete white with respect to the longitudinal black and white pattern. Then, the compensational gray level value with respect to the actual gray level value for each of the pixels is obtained according to the correctional gray level value for complete black, the correctional gray level value for complete white, the theoretical gray level value for complete black, the theoretical gray level value for complete white, and the actual gray level value for each of the pixels. Then, the procedure is complete.

Claims

1. An apparatus comprising:

means for scanning a document and a calibration pattern at the same time along a scanning path, wherein the means for scanning comprises one or more scan lines;

a top;

a scanning chassis configured to be movable under the top along the scanning path, wherein the scanning chassis comprises the scanning element;

a scanning platform disposed at the top, wherein the scanning platform is configured to support the document above the scanning chassis, wherein the calibration pattern is positioned on the top along a lateral side of the scanning platform and extends continuously along substantially an entire length of the scanning path;

means for obtaining actual gray level values from the scanned document and obtaining a correctional gray level value for white and a correctional gray level value for black from the scanned calibration pattern, wherein the actual gray level values and the correctional gray level values are obtained along the one or more scan lines;

means for determining a compensational gray level value for pixels of the scanned document based on an actual gray level value for each of the pixels and the correctional gray level values, wherein determining the compensational gray level value for each of the pixels comprises calculating [(each of the actual gray level values with respect to each of the pixels−

the correctional gray level value for black)÷

(the correctional gray level value for white−

the correctional gray level value for black) * (a theoretical gray level value for white−

a theoretical gray level value for black)]; and

means for compensating a gray level of the scanned document using the compensational gray level value.

2. The apparatus of claim 1, wherein the means for scanning is further configured to continuously scan both the calibration pattern and the document while moving longitudinally along the scanning path.

3. The apparatus of claim 1, wherein the calibration pattern comprises a black pattern and a white pattern that are each elongated in a direction parallel with the scanning path and wherein the means for compensating is further configured to determine the correctional gray level value for black from the black pattern and the correctional gray level value for white from the white pattern.

4. The apparatus of claim 1, wherein the calibration pattern comprises a black pattern, and wherein the means for compensating is further configured to determine the correctional gray level value for black from the black pattern.

5. The apparatus of claim 1, wherein the calibration pattern comprises a white pattern, and wherein the means for compensating is further configured to determine the correctional gray level value for white from the white pattern.

6. The apparatus of claim 1, wherein a length of the calibration pattern is equal to or greater than a length of the scanning path.

7. An apparatus comprising:

a scanning element configured to be moveable in a document scanning direction;

a scanning platform configured to support a document;

a reference pattern disposed adjacent to the scanning platform, wherein the reference pattern is at least as long as the scanning platform in the document scanning direction; and

a processor configured to;

determine actual gray level values for pixels of a scanned image of the document;

determine a correctional gray level value for white and a correctional gray level value for black based, at least in part, on a scanned image of the reference pattern, wherein the reference pattern and the document are scanned at the same time;

determine a compensational gray level value for the pixels of the scanned image based at least in part on an actual gray level for each of the pixels and the correctional gray level, wherein determining the compensational gray level value for each of the pixels comprises calculating [(each of the actual gray level values with respect to each of the pixels−

the correctional gray level value for black)÷

(the correctional gray level value for white−

the correctional gray level value for black) * (a theoretical pray level value for white−

a theoretical gray level value for black)]; and

compensate the scanned image using the compensational gray level value.

8. The apparatus of claim 7, wherein the reference pattern comprises a continuous black pattern elongated in a direction parallel with the document scanning direction and a continuous white pattern elongated in a direction parallel with the document scanning direction and positioned adjacent to the continuous black pattern, and wherein the processor is further configured to determine the correctional gray level value for black from the continuous black pattern and determine the correctional gray level value for white from the continuous white pattern.

9. The apparatus of claim 7, wherein the reference pattern comprises a continuous black pattern, and wherein the processor is further configured to determine the correctional gray level value for black from the continuous black pattern.

10. The apparatus of claim 7, wherein the scanning element is configured to continuously scan both the reference pattern and the document along a scanning path associated with the scanning element.

11. The apparatus of claim 7, wherein the reference pattern comprises a continuous white pattern, and wherein the processor is further configured to determine the correctional gray level value for white from the continuous white pattern.

12. The apparatus of claim 7, wherein a length of the reference pattern is parallel to the scanning direction and equal to or greater than a length of the scanning platform.

13. A method performed by a scanner, comprising:

scanning, with a scanning element of the scanner, a document to determine a plurality of actual gray level values for a plurality of pixels scanned from the document, wherein the scanning element is configured to scan the document along a scanning path associated with the scanner;

scanning, with the scanning element, a continuous longitudinal calibration pattern while scanning the document to determine a correctional gray level value for white, wherein the scanning element is configured to concurrently scan both the calibration pattern and the document at multiple positions along the scanning path;

scanning a second continuous longitudinal calibration pattern while scanning the document to determine a correctional gray level for black;

determining a compensational gray level value with respect to an actual gray level value for each of the pixels, wherein the compensational gray level value is based at least in part on the correctional gray level value and the actual gray level value for each of the pixels scanned from the document, and wherein determining the compensational gray level value for each of the pixels comprises calculating [(each of the actual gray level values with respect to each of the pixels−

the correctional gray level value for black)÷

(the correctional gray level value for white−

the correctional gray level value for black) * (a theoretical gray level value for white−

a theoretical gray level value for black)]; and

compensating for image brightness in a scanned image of the document using the compensational gray level value for each of the pixels.

14. The method according to claim 13, wherein the scanner comprises:

a top;

a scanning chassis configured to be movable under the top along the scanning path, wherein the scanning chassis comprises the scanning element; and

a scanning platform disposed at the top, wherein the scanning platform is configured to support the document above the scanning chassis, wherein the calibration pattern is positioned along a lateral side of the scanning platform and extends continuously along substantially an entire length of the scanning path.

15. A method performed by a scanner including a top, a scanning chassis, and a scanning platform, wherein the method comprises:

scanning, with a scanning element of the scanner, a document and a continuous longitudinal white pattern, wherein the scanning element is configured to continuously scan both the document and the longitudinal white pattern, at the same time, along a scanning path associated with the scanner, wherein the scanning chassis is configured to be movable under the top along the scanning path, wherein the scanning chassis comprises the scanning element, wherein the scanning platform is configured to support the document above the scanning chassis; and

wherein the longitudinal white pattern is positioned on the top along a lateral side of the scanning platform and extends continuously along substantially an entire length of the scanning path;

determining a plurality of actual gray level values for a plurality of pixels scanned from the document;

determining a correctional gray level value for white based at least in part on the longitudinal white pattern;

determining a compensational gray level value with respect to an actual gray level value for each of the pixels based at least in part on the correctional gray level value for white, a theoretical gray level value for white, and the actual gray level value for each of the pixels, wherein determining the compensational gray level value for each of the pixels comprises calculating [each of the actual gray level values with respect to each of the pixels * (the theoretical gray level value for white+the correctional gray level value for white)]; and

compensating a scanned image of the document using the compensational gray level value for each of the pixels.

16. The method of claim 15, wherein the correctional gray level value for white is determined at the same time as at least one of the plurality of actual gray level values.

17. A method performed by a scanner including a top, a scanning chassis, and a scanning platform, wherein the method comprises:

scanning, with a scanning element of the scanner, a document and a continuous longitudinal black pattern, wherein the scanning element is configured to simultaneously scan both the document and the longitudinal black pattern, at the same time, along a scanning path associated with the scanner, wherein the scanning chassis is configured to be movable under the top along the scanning path, wherein the scanning chassis comprises the scanning element, wherein the scanning platform is configured to support the document above the scanning chassis; and

wherein the longitudinal black pattern is positioned on the top along a lateral side of the scanning platform and extends continuously along substantially an entire length of the scanning path;

determining a plurality of actual gray level values for a plurality of pixels from the document;

determining a correctional gray level value for black based at least in part on the longitudinal black pattern;

determining a compensational gray level value with respect to an actual gray level value for each of the pixels based at least in part on the correctional gray level value for black, a theoretical gray level value for black, and the actual gray level value for each of the pixels, wherein determining the compensational gray level value for each of the pixels comprises calculating [each of the actual gray level values with respect to each of the pixels−

(the correctional gray level value for black−

the theoretical gray level value for black)]; and

compensating a scanned image of the document using the compensational gray level value for each of the pixels.