Patent US6249281B1 successfully refreshed from Google Patents.
Patent US6192149B1 successfully refreshed from Google Patents.
US6192149B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for automatic detection of image target gamma
Assignee: Xerox Corp
•
Filing: 1998-04-08
•
Granted: 2001-02-20
•
Expires: 2018-04-08
Abstract
Abstract A method and apparatus are provided for improving the quality of a printed image by first automatically determining the gamma (γ) of an image, and then adjusting the γ of the printer, if necessary, to correspond to that of the image. Thus, if an image has a γ of 2, the γ of the printer will be adjusted from approximately 1 (its normal γ), to approximately 2 (i.e., corresponding to that of the image). To detect the γ difference problem, the invention detects a shift in saturated colors towards higher digital counts. Then, through mapping of the color space from three dimensions to two dimensions and cross-plotting values of saturation and luminance, a cumulative histogram plot of luminance is developed. The histogram displays the 256 luminance bands, arranged in one of eight bands, and normalized from zero to one. A threshold value is established for the cumulative histogram plot and the value of the cumulative histogram is compared to the threshold. If the threshold is exceeded in most of the bands, the γ for the image matches that of the printer. However, if the threshold is not exceeded, a false γ image may be indicated, for example. In this case, the γ of the printer may be automatically adjusted (e.g., increased from approximately 1 to approximately 2). Thus, the printed image will then be of the same quality as the original image.
Inventors
- 👤 Reiner Eschbach
- 👤 Charles M. Hains
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 11:03
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/46; H04N1/56; H04N1/60; G; G06; G06T; G06T5/00; G06T5/40; G06T5/90; G06T5/92; H04N1/40; H04N1/407; H04N1/4072; H04N1/4074
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
70 words
An apparatus for controlling an image output device, comprising: a transform module that forms a cross-plot of a document's effective luminance and effective saturation; a histogram module that generates a histogram based on the cross-plot; a determination module that examines the histogram over a predetermined subset of effective luminance values; and a controller that controls operation of the image output device based on the examination performed by the determination module.
Claim 2
Independent Claim
70 words
An apparatus for controlling an image output device, comprising: a transform module that forms a cross-plot of a document's effective luminance and effective saturation; a histogram module that generates a histogram based on the cross-plot; a determination module that examines the histogram over a predetermined subset of effective luminance values; and a controller that controls operation of the image output device based on the examination performed by the determination module.
Claim 3
Dependent Claim
22 words
The apparatus of claim 1 , wherein the determination module determines a relationship of the predetermined subset with respect to a threshold.
Claim 4
Dependent Claim
36 words
The apparatus of claim 2 , wherein the controller controls the image output device to print an image when the determination module determines that a predetermined number of bands in the predetermined subset exceed the threshold.
Claim 5
Dependent Claim
42 words
The apparatus of claim 2 , wherein the controller controls the image output device to adjust a γ of the image output device when the determination module determines that a predetermined number of bands in the predetermined subset are below the threshold.
Claim 6
Dependent Claim
16 words
The apparatus of claim 4 , wherein the threshold corresponds to a line on the histogram.
Claim 7
Dependent Claim
22 words
The apparatus of claim 5 , wherein the determination module determines whether at least three of the bands are below the threshold.
Claim 8
Dependent Claim
70 words
The apparatus of claim 6 , wherein the transform module computes the document's effective saturation according to the relationship: Effective saturation=max ( r,g,b )−min ( r,g,b )−½+|[½−mid ( r,g,b )]| wherein, max (r,g,b) is a maximum of each of the red, green, and blue triplets, min (r,g,b) is a minimum of each red, green, and blue triplet, and mid (r,g,b) is the mid-point of each red, green, and blue triplet.
Claim 9
Dependent Claim
55 words
The apparatus of claim 7 , wherein the transform module computes the document's effective luminance according to the relationship: Effective luminance=½×[max ( r,g,b )+min ( r,g,b )] wherein, max (r,g,b) is a maximum of each of the red, green, and blue triplets and min (r,g,b) is a minimum of each red, green, and blue triplet.
Claim 10
Dependent Claim
11 words
The apparatus of claim 1 , wherein the histograms are self-normalized.
Claim 11
Independent Claim
66 words
An apparatus for controlling an image output device, comprising: cross-plot forming means for forming a cross-plot of a document's effective luminance and effective saturation; generating means for generating a histogram based on the cross-plot; determining means for examining the histogram over a predetermined subset of effective luminance values; and controlling means for controlling the image output device based on the examination performed by the determining means.
Claim 12
Independent Claim
66 words
An apparatus for controlling an image output device, comprising: cross-plot forming means for forming a cross-plot of a document's effective luminance and effective saturation; generating means for generating a histogram based on the cross-plot; determining means for examining the histogram over a predetermined subset of effective luminance values; and controlling means for controlling the image output device based on the examination performed by the determining means.
Claim 13
Dependent Claim
22 words
The apparatus of claim 10 , wherein the determining means determines a relationship of the predetermined subset with respect to a threshold.
Claim 14
Dependent Claim
37 words
The apparatus of claim 11 , wherein the controlling means controls the image output device to print an image when the determining means determines that a predetermined number of bands in the predetermined subset exceed the threshold.
Claim 15
Dependent Claim
43 words
The apparatus of claim 11 , wherein the controlling means controls the image output device to adjust a γ of the image output device when the determining means determines that a predetermined number of bands in the predetermined subset are below the threshold.
Claim 16
Dependent Claim
16 words
The apparatus of claim 13 , wherein the threshold corresponds to a line on the histogram.
Claim 17
Dependent Claim
22 words
The apparatus of claim 14 , wherein the determining means determines whether at least three of the bands are below the threshold.
Claim 18
Dependent Claim
70 words
The apparatus of claim 15 , wherein the computing means computes the document's effective saturation according to the relationship: Effective saturation=max ( r,g,b )−min ( r,g,b )−½+|[½−mid ( r,g,b )]| wherein, max (r,g,b) is a maximum of each of the red, green, and blue triplets, min (r,g,b) is a minimum of each red, green, and blue triplet, and mid (r,g,b) is the mid-point of each red, green, and blue triplet.
Claim 19
Dependent Claim
56 words
The apparatus of claim 16 , wherein the computing means computes the document's effective luminance according to the relationship: Effective luminance=½×[max ( r,g,b )+min ( r,g,b )] wherein, wherein, max (r,g,b) is a maximum of each of the red, green, and blue triplets and min (r,g,b) is a minimum of each red, green, and blue triplet.
Claim 20
Dependent Claim
11 words
The apparatus of claim 10 , wherein the histograms are self-normalized.
Claim 21
Independent Claim
49 words
A method for automatically detecting an image γ, comprising: forming a cross-plot of the document's effective luminance and effective saturation; generating a histogram based on the cross-plot; examining the histogram over a predetermined subset of effective luminance values; and controlling an image output device based on the examining step.
Claim 22
Independent Claim
49 words
A method for automatically detecting an image γ, comprising: forming a cross-plot of the document's effective luminance and effective saturation; generating a histogram based on the cross-plot; examining the histogram over a predetermined subset of effective luminance values; and controlling an image output device based on the examining step.
Claim 23
Dependent Claim
20 words
The method of claim 19 , further comprising determining a relationship of the predetermined subset with respect to a threshold.
Claim 24
Dependent Claim
37 words
The method of claim 20 , wherein the controlling step controls the image output device to print an image when the determining step determines that a predetermined number of bands in the predetermined subset exceed the threshold.
Claim 25
Dependent Claim
43 words
The method of claim 20 , wherein the controlling step controls the image output device to adjust a γ of the image output device when the determining step determines that a predetermined number of bands in the predetermined subset are below the threshold.
Claim 26
Dependent Claim
16 words
The method of claim 22 , wherein the threshold corresponds to a line on the histogram.
Claim 27
Dependent Claim
22 words
The method of claim 23 , wherein the determining step determines whether at least three of the bands are below the threshold.
Claim 28
Dependent Claim
69 words
The method of claim 24 , wherein the computing step computes the effective saturation according to the relationship: Effective saturation=max ( r,g,b )−min ( r,g,b )−½+|[½−mid ( r,g,b )]| wherein, max (r,g,b) is a maximum of each of the red, green, and blue triplets, min (r,g,b) is a minimum of each red, green, and blue triplet, and mid (r,g,b) is the mid-point of each red, green, and blue triplet.
Claim 29
Dependent Claim
54 words
The method of claim 25 , wherein the computing step computes the effective luminance according to the relationship: Effective luminance=½×[max ( r,g,b )+min ( r,g,b )] wherein, max (r,g,b) is a maximum of each of the red, green, and blue triplets and min (r,g,b) is a minimum of each red, green, and blue triplet.
Claim 30
Dependent Claim
11 words
The method of claim 19 , wherein the histograms are self-normalized.
References Cited (Backward Citations)
US5357352A
Cited
US5414538A
Cited
US5450502A
Cited
US5371615A
Cited
US5347374A
Cited
US5363209A
Cited
US5450217A
Cited
US5581370A
Cited
US5812286A
Cited
US5991511A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-02-20 | 2004-08-21 | 2005-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-02-20 | 2008-08-21 | 2009-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-02-20 | 2012-08-21 | 2013-02-20 | $7700.00 | Window Closed / Lapsed |