US6665447B1
Expired / Lapsed
US
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Method for enhancing image data by sharpening
Assignee: Hewlett Packard Development Co LP
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Filing: 1999-07-26
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Granted: 2003-12-16
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Expires: 2019-07-26
Abstract
Abstract A process for enhancing a decompressed JPEG image data defined by a two-dimensional array of pixel values is disclosed. The enhancement involves sharpening real objects in the image and avoids the sharpening of compression artifacts. The process includes selecting a first pixel value to be enhanced, a group of pixel values surrounding the first pixel from the array of pixel values, and a threshold value. The first pixel value is changed to an enhanced value by first taking the differences in pixel values between each pixel value in the group and the first pixel. These differences in values are compared with the threshold value. Those differences in values that exceed the threshold value are then used to calculate the enhanced value. More specifically, the enhanced value is given by the sum of a scaled average of the differences in values and the original pixel value.
Inventors
- 👤 San San Chan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:35
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/73; G06T5/75
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
121 words
A process for enhancing a pixel value in an image data defined by a two dimensional array of pixel values comprising the steps of: selecting a first pixel value to be enhanced from the array of pixel values; selecting a group of pixel values surrounding the first pixel value; and changing the first pixel value to an enhanced second pixel value as a function of differences in values between each of the pixel values in the selected group and the first pixel value, the differences in values are to exceed a threshold value; wherein the image data comprises decompressed JPEG image data which contains JPEG compression artifacts and wherein the threshold value is selected to avoid enhancing the JPEG compression artifacts.
Claim 2
Dependent Claim
121 words
A process for enhancing a pixel value in an image data defined by a two dimensional array of pixel values comprising the steps of: selecting a first pixel value to be enhanced from the array of pixel values; selecting a group of pixel values surrounding the first pixel value; and changing the first pixel value to an enhanced second pixel value as a function of differences in values between each of the pixel values in the selected group and the first pixel value, the differences in values are to exceed a threshold value; wherein the image data comprises decompressed JPEG image data which contains JPEG compression artifacts and wherein the threshold value is selected to avoid enhancing the JPEG compression artifacts.
Claim 3
Dependent Claim
83 words
A process for enhancing a pixel value according to claim 1 , wherein the step of changing the first pixel value to an enhance second pixel value comprises the steps of: scaling differences in values between each of the pixel values in the selected group and the first pixel value by again value; identifying scaled difference values which exceed a threshold value; and adding an average of the identified difference values to the first pixel value to give the enhanced second pixel value.
Claim 4
Dependent Claim
40 words
A process for enhancing a pixel value according to claim 1 , wherein the threshold value is selected based on a scaling value which is used in determining quantization step sizes for a quantization matrix in a JPEG compression process.
Claim 5
Dependent Claim
167 words
A process for enhancing a pixel value in an image data defined by a two-dimensional array of pixel values comprising the steps of: selecting a first pixel value to be enhanced, X, from the array of pixel values; selecting a group of pixel values each identified by p(i), surrounding the first pixel value, X, from the array of pixel values; selecting each pixel value p(i) from the group of pixel values to calculate a scaled difference in pixel values between the selected pixel value, p(i), and the first pixel value, X, until scaled difference values have been calculated for substantially all pixel values in the selected group of pixel values, the scaled difference in pixel values being given by a formula (X−p(i)*GAIN, where GAIN is a scaling factor; identifying scaled difference values whose magnitudes exceed a threshold value,THRESHOLD; and deriving an enhanced second pixel value for the first pixel value, X, by adding an average of the identified scaled difference values to the first pixel value, X.
Claim 6
Dependent Claim
167 words
A process for enhancing a pixel value in an image data defined by a two-dimensional array of pixel values comprising the steps of: selecting a first pixel value to be enhanced, X, from the array of pixel values; selecting a group of pixel values each identified by p(i), surrounding the first pixel value, X, from the array of pixel values; selecting each pixel value p(i) from the group of pixel values to calculate a scaled difference in pixel values between the selected pixel value, p(i), and the first pixel value, X, until scaled difference values have been calculated for substantially all pixel values in the selected group of pixel values, the scaled difference in pixel values being given by a formula (X−p(i)*GAIN, where GAIN is a scaling factor; identifying scaled difference values whose magnitudes exceed a threshold value,THRESHOLD; and deriving an enhanced second pixel value for the first pixel value, X, by adding an average of the identified scaled difference values to the first pixel value, X.
Claim 7
Dependent Claim
37 words
A process for enhancing a pixel value according to claim 4 , wherein the average of the identified scaled difference values is taken over substantially the number of pixel values in the selected group of pixel values.
Claim 8
Dependent Claim
144 words
A program storage device readable by a computing device, tangibly embodying a program of instructions, executable by the computing device to perform the method steps for enhancing a pixel value in an image data defined by a two-dimensional array of pixel values, the method comprising the steps of: selecting a first pixel value to be enhanced from the array of pixel values; selecting a group of pixel values surrounding the first pixel; and changing the first pixel value to an enhanced second pixel value as a function of differences in values between each of the pixel values in the selected group and the first pixel value, the difference in values are to exceed a threshold value; wherein the image data comprises decompressed JPEG image data which contains JPEG compression artifacts and wherein the threshold value is selected to avoid enhancing the JPEG compression artifacts.
Claim 9
Dependent Claim
144 words
A program storage device readable by a computing device, tangibly embodying a program of instructions, executable by the computing device to perform the method steps for enhancing a pixel value in an image data defined by a two-dimensional array of pixel values, the method comprising the steps of: selecting a first pixel value to be enhanced from the array of pixel values; selecting a group of pixel values surrounding the first pixel; and changing the first pixel value to an enhanced second pixel value as a function of differences in values between each of the pixel values in the selected group and the first pixel value, the difference in values are to exceed a threshold value; wherein the image data comprises decompressed JPEG image data which contains JPEG compression artifacts and wherein the threshold value is selected to avoid enhancing the JPEG compression artifacts.
Claim 10
Dependent Claim
80 words
A program storage device according to claim 6 wherein the step of changing the first pixel value to an enhanced second pixel value comprises the steps of: scaling differences in values between each of the pixel values in the selected group and the first pixel value by a gain value; identifying scaled difference values which exceed the threshold value; and adding an average of the identified difference values to the first pixel value to give the enhanced second pixel value.
Claim 11
Dependent Claim
37 words
A program storage device according to claim 6 , wherein the threshold value is selected based on a scaling value which is used in determining quantization step sizes for a quantization matrix in a JPEG compression process.
Claim 12
Independent Claim
88 words
A method for sharpeninig a decompressed JPEG color image, comprising: decompressing image values which have been previously transformed, divided, discret-cosine-transformed, quantized, and encoded with headers that include quantization tables and coding tables to recover a set of reconstructed pixel values; smoothing data obtained in the step of decompressing to reduce pixel-to-pixel discontinuities; sharpening in a single pass the data obtained in the step of smoothing; halftoning data derived from the step of sharpening; and forwarding the data obtained in the step of halftoning for an inkjet print engine.
Claim 13
Independent Claim
88 words
A method for sharpeninig a decompressed JPEG color image, comprising: decompressing image values which have been previously transformed, divided, discret-cosine-transformed, quantized, and encoded with headers that include quantization tables and coding tables to recover a set of reconstructed pixel values; smoothing data obtained in the step of decompressing to reduce pixel-to-pixel discontinuities; sharpening in a single pass the data obtained in the step of smoothing; halftoning data derived from the step of sharpening; and forwarding the data obtained in the step of halftoning for an inkjet print engine.
Claim 14
Dependent Claim
98 words
The method of claim 9 , wherein the step of sharpening further comprises: receiving a two-dimensional array of pixel values of a smoothing image from the step of smoothing and that includes JPEG compression artifacts; processing to sharpen real objects in said two-dimensional array of pixel values while avoiding said JPEG compression artifacts by calculating pixel-by-pixel an enhanced value for a luminance component that is dependent on each of its surrounding pixel values if the particular pixel value exceeds a threshold value; and amplifying said enhanced value for each said luminance component by an empirically determined gain value.
Claim 15
Independent Claim
108 words
A method of sharpening image pixels for a printer, comprising: receiving a two-dimensional array of pixel values of a smoothing image from a smoothing process that included JPEG compression artifacts; processing to sharpen real objects in said two-dimensional array of pixel values while avoiding said JPEG compression artifacts by calculating pixel-by-pixel an enhanced value for a luminance component that is dependent on each of its surrounding pixel values if the particular pixel value exceeds a threshold value; amplifying said enhanced value for each said luminance component by an empirically determined gain value; and halftoning data obtainied in the step of amplifying for use by an inkjet print engine.
Claim 16
Independent Claim
108 words
A method of sharpening image pixels for a printer, comprising: receiving a two-dimensional array of pixel values of a smoothing image from a smoothing process that included JPEG compression artifacts; processing to sharpen real objects in said two-dimensional array of pixel values while avoiding said JPEG compression artifacts by calculating pixel-by-pixel an enhanced value for a luminance component that is dependent on each of its surrounding pixel values if the particular pixel value exceeds a threshold value; amplifying said enhanced value for each said luminance component by an empirically determined gain value; and halftoning data obtainied in the step of amplifying for use by an inkjet print engine.
References Cited (Backward Citations)
US4783840A
Cited
US6002407A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2006-12-15 | 2007-06-16 | 2007-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2010-12-15 | 2011-06-16 | 2011-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2014-12-15 | 2015-06-16 | 2015-12-16 | $7700.00 | Window Closed / Lapsed |