Patent US5793885A successfully refreshed from Google Patents.
US5793885A
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Computationally efficient low-artifact system for spatially filtering digital color images
Assignee: International Business Machines Corp
•
Filing: 1997-07-23
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Granted: 1998-08-11
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Expires: 2017-07-23
Abstract
Abstract A computationally efficient system spatially filters a digital input image to sharpen the image. A process is disclosed to spatially filter pixels of an RGB image by applying a high pass filter to the image. First, signals representative of luminance are extracted from the input image. Then, the extracted luminance signals are filtered. Quotient signals are then developed, representing the ratio between each filtered luminance signal and the corresponding original luminance signal. Quotient signals are multiplied by the corresponding pixels of each plane of the original image to provide an output image. The invention may also be embodied by an image editor to implement the spatial filtering process of the invention, where the image editor includes stored programming instructions executed by a processor, discrete circuit components, an ASIC, or another suitable hardware device.
Inventors
- 👤 James Matthews Kasson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:57
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/20
Claims Analysis
Total Claims: 75
Claim 1
Independent Claim
132 words
A method of modifying colors of pixels in a digital color input image, comprising the steps of: receiving a digital color input image, where said input image includes multiple input pixels, each pixel including red, blue, and green components; developing luminance signals, each representing the luminance of a corresponding pixel of a selected group of the input pixels; processing the selected group of pixels by performing steps comprising: spatially filtering the luminance signals to provide filtered luminance signals corresponding thereto; generating quotient signals representing the filtered luminance signals divided by their corresponding luminance signals; and multiplying the components of the selected group of input pixels by corresponding quotient signals to create output signals; and directing the output signals to an output device to display an output image corresponding to the output signals.
Claim 2
Independent Claim
132 words
A method of modifying colors of pixels in a digital color input image, comprising the steps of: receiving a digital color input image, where said input image includes multiple input pixels, each pixel including red, blue, and green components; developing luminance signals, each representing the luminance of a corresponding pixel of a selected group of the input pixels; processing the selected group of pixels by performing steps comprising: spatially filtering the luminance signals to provide filtered luminance signals corresponding thereto; generating quotient signals representing the filtered luminance signals divided by their corresponding luminance signals; and multiplying the components of the selected group of input pixels by corresponding quotient signals to create output signals; and directing the output signals to an output device to display an output image corresponding to the output signals.
Claim 3
Dependent Claim
17 words
The method of claim 1, wherein the selected group of pixels comprises all pixels of the image.
Claim 4
Dependent Claim
61 words
The method of claim 1, wherein the spatially filtering step comprises the steps of: providing modified luminance signals by converting the luminance signals from an original domain to a frequency-based domain; providing filtered luminance signals by reducing modified luminance signals having frequencies greater than a selected level; and converting the filtered luminance signals from the frequency-based domain to the original domain.
Claim 5
Dependent Claim
13 words
The method of claim 3, wherein the frequency-based domain comprises the Fourier domain.
Claim 6
Dependent Claim
78 words
The method of claim 1, wherein the processing step comprises the steps of: selecting a pixel; spatially filtering a luminance signal corresponding to the selected pixel to provide a filtered signal corresponding thereto; generating a quotient signal representing the filtered signal divided by its corresponding luminance signal; multiplying the components of the selected pixel by the quotient signal to create an output signal; and repeating the selecting, generating, and multiplying steps for remaining pixels of the selected group.
Claim 7
Dependent Claim
86 words
The method of claim 1, wherein the processing step comprises the steps of: spatially filtering each of the luminance signals to provide a set of filtered luminance signals corresponding to the selected group of pixels; generating a set of quotient signals corresponding to the selected group of pixels each quotient signal representing a filtered signal divided by its corresponding luminance signal; and multiplying the components of each pixel in the selected group of pixels by the corresponding quotient signal to create a set of output signals.
Claim 8
Dependent Claim
41 words
The method of claim 5, wherein the spatial filtering step comprises the steps of convolving the luminance signal corresponding to the selected pixel with luminance signals corresponding to predetermined pixels of the selected group in accordance with a pre-prepared filtered kernel.
Claim 9
Dependent Claim
38 words
The method of claim 6, wherein the spatially filtering step comprises the steps of convolving each of the luminance signals with luminance signals corresponding to predetermined pixels of the selected group in accordance with a pre-prepared filter kernel.
Claim 10
Dependent Claim
14 words
The method of claim 7, further comprising the steps of preparing the filter kernel.
Claim 11
Dependent Claim
14 words
The method of claim 8, further comprising the steps of preparing the filter kernel.
Claim 12
Dependent Claim
26 words
The method of claim 1, wherein the red, green, and blue components of the pixels of the input image are represented in CCIR 709 RGB format.
Claim 13
Dependent Claim
25 words
The method of claim 1, wherein the red, green, and blue components of the pixels of the input image are represented in SMPTE-C RGB format.
Claim 14
Dependent Claim
52 words
The method of claim 1, wherein the developing step comprises the steps of: removing nonlinearity from the red, green, and blue pixel components of the input image to provide linearized red, green, and blue components; and providing a luminance signal by combining the linearized red, green, and blue components in predetermined proportions.
Claim 15
Dependent Claim
27 words
The method of claim 1, wherein the developing step comprises the steps of providing a luminance signal in accordance with a color space compatible with CIE Yxy.
Claim 16
Dependent Claim
52 words
The method of claim 14, wherein the providing step comprises the steps of: removing nonlinearity from the red, green, and blue pixel components of the input image to provide a linearized red component R, linearized green component G, and linearized blue component B; and providing a luminance signal Y as follows: Y=0.2123R+0.7011G+0.0865B.
Claim 17
Dependent Claim
52 words
The method of claim 14, wherein the providing step comprises the steps of: removing nonlinearity from the red, green, and blue pixel components of the input image to provide a linearized red component R, linearized green component G, and linearized blue component B; and providing a luminance signal Y as follows: Y=0.2126R+0.752G+0.0722B.
Claim 18
Dependent Claim
39 words
The method of claim 1, wherein the developing step comprises the steps of providing a luminance signal in accordance with a color space compatible with NTSC Y by combining the red, green, and blue pixel components in predetermined proportions.
Claim 19
Dependent Claim
27 words
The method of claim 1, wherein the developing step comprises the steps of providing a luminance signal in accordance with a color space compatible with NTSC Y.
Claim 20
Dependent Claim
39 words
The method of claim 18, wherein the providing step comprises the steps of providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.2999R'+0.587G'+0.114B'. 20.
Claim 21
Dependent Claim
38 words
The method of claim 18, wherein the providing step comprises the steps of providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.3R'+0.59G'+0.11B'.
Claim 22
Dependent Claim
38 words
The method of claim 18, wherein the providing step comprises the steps of providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.25R'+0.625G'+0.125B'.
Claim 23
Dependent Claim
38 words
The method of claim 18, wherein the providing step comprises the steps of providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.25R'+0.75G'.
Claim 24
Dependent Claim
21 words
The method of claim 1, wherein the generating step additionally comprises the step of applying gamma correction to the quotient signal.
Claim 25
Dependent Claim
37 words
The method of claim 1, the red, blue, and green components of the input image being nonlinear signals, wherein each luminance signal represents linearized luminance of a corresponding pixel of a selected group of the input pixels.
Claim 26
Dependent Claim
142 words
An image editing apparatus for modifying colors of pixels of a digital color input image contained in a source of a digital color input image, where said input image includes multiple input pixels, each pixel including red, blue, and green components, said image editor comprising: an extractor electrically connected to the source to develop luminance signals each representing the luminance of a corresponding pixel of a selected group of the input pixels; a spatial filter electrically connected to the extractor to spatially filter the luminance signals to provide filtered luminance signals corresponding thereto; a divider electrically connected to the filter to generate quotient signals representing the filtered luminance signals divided by their corresponding luminance signals; and a multiplier electrically connected to the divider to multiply the components of the selected group of input pixels by corresponding quotient signals to create output signals.
Claim 27
Dependent Claim
142 words
An image editing apparatus for modifying colors of pixels of a digital color input image contained in a source of a digital color input image, where said input image includes multiple input pixels, each pixel including red, blue, and green components, said image editor comprising: an extractor electrically connected to the source to develop luminance signals each representing the luminance of a corresponding pixel of a selected group of the input pixels; a spatial filter electrically connected to the extractor to spatially filter the luminance signals to provide filtered luminance signals corresponding thereto; a divider electrically connected to the filter to generate quotient signals representing the filtered luminance signals divided by their corresponding luminance signals; and a multiplier electrically connected to the divider to multiply the components of the selected group of input pixels by corresponding quotient signals to create output signals.
Claim 28
Dependent Claim
17 words
The apparatus of claim 25, wherein the selected group of pixels comprises all pixels of the image.
Claim 29
Dependent Claim
63 words
The apparatus of claim 25, wherein the spatial filter comprises: means for providing modified luminance signals by converting the luminance signals from an original domain to a frequency-based domain; means for providing filtered luminance signals by reducing modified luminance signals having frequencies greater than a selected level; and means for converting the filtered luminance signals from the frequency-based domain to the original domain.
Claim 30
Dependent Claim
13 words
The apparatus of claim 27, wherein the frequency-based domain comprises the Fourier domain.
Claim 31
Dependent Claim
34 words
The apparatus of claim 25, wherein the spatial filter comprises means for convolving each luminance signal with luminance signals corresponding to predetermined pixels of the selected group in accordance with a pre-prepared filtered kernel.
Claim 32
Dependent Claim
26 words
The apparatus of claim 25, wherein the red, green, and blue components of the pixels of the input image are represented in CCIR 709 RGB format.
Claim 33
Dependent Claim
25 words
The apparatus of claim 25, wherein the red, green, and blue components of the pixels of the input image are represented in SMPTE-C RGB format.
Claim 34
Dependent Claim
52 words
The apparatus of claim 25, wherein the extractor comprises: means for removing nonlinearity from the red, green, and blue pixel components of the input image to provide linearized red, green, and blue components; and means for providing a luminance signal by combining the linearized red, green, and blue components in predetermined proportions.
Claim 35
Dependent Claim
26 words
The apparatus of claim 25, wherein the extractor comprises a means for providing a luminance signal in accordance with a color space compatible with CIE Yxy.
Claim 36
Dependent Claim
53 words
The apparatus of claim 33, wherein the extractor comprises: means for removing nonlinearity from the red, green, and blue pixel components of the input image to provide a linearized red component R, linearized green component G, and linearized blue component B; and means for providing a luminance signal Y as follows: Y=0.2123R+0.7011G+0.0865B. 35.
Claim 37
Dependent Claim
52 words
The apparatus of claim 33, wherein the extractor comprises: means for removing nonlinearity from the red, green, and blue pixel components of the input image to provide a linearized red component R, linearized green component G, and linearized blue component B; and means for providing a luminance signal Y as follows: Y=0.2126R+0.752G+0.0722B.
Claim 38
Dependent Claim
37 words
The apparatus of claim 25, wherein the extractor comprises means for providing a luminance signal in accordance with a color space compatible with NTSC Y by combining the red, green, and blue pixel components in predetermined proportions.
Claim 39
Dependent Claim
25 words
The apparatus of claim 25, wherein the extractor comprises means for providing a luminance signal in accordance with a color space compatible with NTSC Y.
Claim 40
Dependent Claim
36 words
The apparatus of claim 37, wherein the extractor comprises means for providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.2999R'+0.587G'+0.114B'.
Claim 41
Dependent Claim
37 words
The apparatus of claim 37, wherein the extractor comprises means for providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.3R'+0.59G'+0.11B'. 40.
Claim 42
Dependent Claim
36 words
The apparatus of claim 37, wherein the extractor comprises means for providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.25R'+0.625G'+0.125B'.
Claim 43
Dependent Claim
36 words
The apparatus of claim 37, wherein the extractor comprises means for providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.25R'+0.75G'.
Claim 44
Dependent Claim
19 words
The apparatus of claim 25, wherein the divider additionally comprises means for applying gamma correction to the quotient signal.
Claim 45
Dependent Claim
37 words
The apparatus of claim 25, the red, blue, and green components of the input image being nonlinear signals, wherein each luminance signal represents linearized luminance of a corresponding pixel of a selected group of the input pixels.
Claim 46
Dependent Claim
157 words
A program storage device readable by a digital processing apparatus and tangibly embodying a program of instructions executable by the digital processing apparatus to perform method steps for modifying colors of pixels of a digital color input image, said method steps comprising: receiving a digital color input image, where said input image includes multiple input pixels, each pixel including red, blue, and green components; developing luminance signals, each representing the luminance of a corresponding pixel of a selected group of the input pixels; processing the selected group of pixels by performing steps comprising: spatially filtering the luminance signals to provide filtered luminance signals corresponding thereto; generating quotient signals representing the filtered luminance signals divided by their corresponding luminance signals; and multiplying the components of the selected group of input pixels by corresponding quotient signals to create output signals; and directing the output signals to an output device to display an output image corresponding to the output signals.
Claim 47
Dependent Claim
157 words
A program storage device readable by a digital processing apparatus and tangibly embodying a program of instructions executable by the digital processing apparatus to perform method steps for modifying colors of pixels of a digital color input image, said method steps comprising: receiving a digital color input image, where said input image includes multiple input pixels, each pixel including red, blue, and green components; developing luminance signals, each representing the luminance of a corresponding pixel of a selected group of the input pixels; processing the selected group of pixels by performing steps comprising: spatially filtering the luminance signals to provide filtered luminance signals corresponding thereto; generating quotient signals representing the filtered luminance signals divided by their corresponding luminance signals; and multiplying the components of the selected group of input pixels by corresponding quotient signals to create output signals; and directing the output signals to an output device to display an output image corresponding to the output signals.
Claim 48
Dependent Claim
17 words
The device of claim 44, wherein the selected group of pixels comprises all pixels of the image.
Claim 49
Dependent Claim
61 words
The device of claim 45, wherein the spatially filtering step comprises the steps of: providing modified luminance signals by converting the luminance signals from an original domain to a frequency-based domain; providing filtered luminance signals by reducing modified luminance signals having frequencies greater than a selected level; and converting the filtered luminance signals from the frequency-based domain to the original domain.
Claim 50
Dependent Claim
13 words
The device of claim 46, wherein the frequency-based domain comprises the Fourier domain.
Claim 51
Dependent Claim
77 words
The device of claim 44, wherein the processing step comprises the steps of: selecting a pixel; spatially filtering a luminance signal corresponding to the selected pixel to provide filtered signal corresponding thereto; generating a quotient signal representing the filtered signal divided by its corresponding luminance signal; multiplying the components of the selected pixel by the quotient signal to create an output signal; and repeating the selecting, generating, and multiplying steps for remaining pixels of the selected group.
Claim 52
Dependent Claim
86 words
The device of claim 44, wherein the processing step comprises the steps of: spatially filtering each of the luminance signals to provide a set of filtered luminance signals corresponding to the selected group of pixels; generating a set of quotient signals corresponding to the selected group of pixels each quotient signal representing a filtered signal divided by its corresponding luminance signal; and multiplying the components of each pixel in the selected group of pixels by the corresponding quotient signal to create a set of output signals.
Claim 53
Dependent Claim
41 words
The device of claim 48, wherein the spatial filtering step comprises the steps of convolving the luminance signal corresponding to the selected pixel with luminance signals corresponding to predetermined pixels of the selected group in accordance with a pre-prepared filtered kernel.
Claim 54
Dependent Claim
39 words
The device of claim 49, wherein the spatially filtering step comprises the steps of convolving each of the luminance signals with luminance signals corresponding to predetermined pixels of the selected group pixels in accordance with a pre-prepared filter kernel.
Claim 55
Dependent Claim
14 words
The device of claim 50, further comprising the steps of preparing the filter kernel.
Claim 56
Dependent Claim
14 words
The device of claim 51, further comprising the steps of preparing the filter kernel.
Claim 57
Dependent Claim
26 words
The device of claim 44, wherein the red, green, and blue components of the pixels of the input image are represented in CCIR 709 RGB format.
Claim 58
Dependent Claim
25 words
The device of claim 44, wherein the red, green, and blue components of the pixels of the input image are represented in SMPTE-C RGB format.
Claim 59
Dependent Claim
52 words
The device of claim 44, wherein the developing step comprises the steps of: removing nonlinearity from the red, green, and blue pixel components of the input image to provide linearized red, green, and blue components; and providing a luminance signal by combining the linearized red, green, and blue components in predetermined proportions.
Claim 60
Dependent Claim
27 words
The device of claim 44, wherein the developing step comprises the steps of providing a luminance signal in accordance with a color space compatible with CIE Yxy.
Claim 61
Dependent Claim
53 words
The device of claim 57, wherein the providing step comprises the steps of: removing nonlinearity from the red, green, and blue pixel components of the input image to provide a linearized red component R, linearized green component G, and linearized blue component B; and providing a luminance signal Y as follows: Y=0.2123R+0.7011G+0.0865B. 59.
Claim 62
Dependent Claim
52 words
The device of claim 57, wherein the providing step comprises the steps of: removing nonlinearity from the red, green, and blue pixel components of the input image to provide a linearized red component R, linearized green component G, and linearized blue component B; and providing a luminance signal Y as follows: Y=0.2126R+0.752G+0.0722B.
Claim 63
Dependent Claim
39 words
The device of claim 44, wherein the developing step comprises the steps of providing a luminance signal in accordance with a color space compatible with NTSC Y by combining the red, green, and blue pixel components in predetermined proportions.
Claim 64
Dependent Claim
27 words
The device of claim 44, wherein the developing step comprises the steps of providing a luminance signal in accordance with a color space compatible with NTSC Y.
Claim 65
Dependent Claim
38 words
The device of claim 61, wherein the providing step comprises the steps of providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.2999R'+0.587G'+0.114B'.
Claim 66
Dependent Claim
39 words
The device of claim 61, wherein the providing step comprises the steps of providing a luminance signal Y' in relation to the red pixel component R', green pixel component G'. and blue color component B', as follows: Y'=0.3R'+0.59G'+0.11B'. 64.
Claim 67
Dependent Claim
38 words
The device of claim 61, wherein the providing step comprises the steps of providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.25R'+0.625G'+0.125B'.
Claim 68
Dependent Claim
38 words
The device of claim 61, wherein the providing step comprises the steps of providing a luminance signal Y' in relation to the red pixel component R', green pixel component G', and blue color component B', as follows: Y'=0.25R'+0.75G'.
Claim 69
Dependent Claim
21 words
The device of claim 44, wherein the generating step additionally comprises the step of applying gamma correction to the quotient signal.
Claim 70
Dependent Claim
37 words
The device of claim 44, the red, blue, and green components of the input image being nonlinear signals, wherein each luminance signal represents linearized luminance of a corresponding pixel of a selected group of the input pixels.
Claim 71
Dependent Claim
22 words
The device of claim 44, wherein the device comprises a portable diskette readable by a diskette drive of the digital processing apparatus.
Claim 72
Dependent Claim
14 words
The device of claim 44, wherein the device comprises a direct access storage device.
Claim 73
Dependent Claim
25 words
The method of claim 1, the selected group of pixels being a portion of pixels of the image less than all pixels of the image.
Claim 74
Dependent Claim
25 words
The apparatus of claim 25, the selected group of pixels being a portion of pixels of the image less than all pixels of the image.
Claim 75
Dependent Claim
27 words
The program storage device of claim 44, the selected group of pixels being a portion of pixels of the image less than all pixels of the image.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2001-08-10 | 2002-02-09 | 2002-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-08-10 | 2006-02-09 | 2006-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-08-10 | 2010-02-09 | 2010-08-11 | $7700.00 | Window Closed / Lapsed |