EP1073014A2
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EP
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Method for enhancing image data with compression artifacts by selective sharpening
Assignee: HP Inc
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Filing: 2000-07-11
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Granted: —
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Expires: 2020-07-11
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
EP
Data Source
google_patents
Last Synchronized
2026-11-09 17:34
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/73; G06T5/75
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
92 words
A process of 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.
Claim 2
Dependent Claim
34 words
A process according to claim 1, 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
78 words
A process according to claim 2, 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 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
34 words
A process according to Claim 2, 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
163 words
A process of 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 (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
31 words
A process according to claim 5, 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 7
Dependent Claim
116 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 differences in values are to
exceed a threshold value.
Claim 8
Dependent Claim
36 words
A program storage device according to claim 7, 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
80 words
A program storage device according to claim 8, 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 10
Dependent Claim
36 words
A program storage device according to claim 8, 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.
References Cited (Backward Citations)
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