Patent US5170152A successfully refreshed from Google Patents.
US5170152A
Expired / Lapsed
US
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Luminance balanced encoder
Assignee: HP Inc
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Filing: 1990-12-14
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Granted: 1992-12-08
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Expires: 2010-12-14
Abstract
Abstract A color encoder for reducing visible artifacts even when the values of the respective color signals are truncated during encoding. Since the human eye is most sensitive to luminance variations in the displayed image, luminance errors (and hence visible artifacts) are minimized by adding red and green color error signals to the blue color intensity signal prior to encoding so that luminance detail may be maintained. The blue channel is chosen for this purpose since the human eye is least sensitive to changes in blue and yellow. The color maps for the resulting encoded signals may be scaled such that the red and green values are raised and/or the blue values lowered so as to maintain the same relative intensity of luminance in the displayed image. Errors in the displayed luminance signal may thus be made up to four times smaller without increasing the amount of memory required and without adding expensive processing circuitry.
Inventors
- 👤 Gary L. Taylor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:17
CPC Classifications
G; G09; G09G; G09G5/00; G09G5/02; H; H04; H04N; H04N9/00; H04N9/64; H04N9/646
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
99 words
A color encoder for encoding respective color intensity signals for each pixel to be displayed on a video display unit, comprising: means for separately encoding the respective color intensity signals for each pixel of said video display unit; and means for adjusting, prior to encoding by said encoding means, the intensities of the respective color intensity signals at each pixel in accordance with the intensities of the other respective color intensity signals for that pixel so as to minimize visible luminance artifacts in the displayed image as a result of the encoding of each pixel by said encoding means.
Claim 2
Dependent Claim
99 words
A color encoder for encoding respective color intensity signals for each pixel to be displayed on a video display unit, comprising: means for separately encoding the respective color intensity signals for each pixel of said video display unit; and means for adjusting, prior to encoding by said encoding means, the intensities of the respective color intensity signals at each pixel in accordance with the intensities of the other respective color intensity signals for that pixel so as to minimize visible luminance artifacts in the displayed image as a result of the encoding of each pixel by said encoding means.
Claim 3
Dependent Claim
120 words
A color encoder for encoding respective color intensity signals for each pixel to be displayed on a video display unit, comprising: means for dividing said respective color intensity signals for each pixel into first signals having a predetermined number of bits and error signals, said first signals being output as encoded color intensity signals; and means responsive to an error signal of at least one of said respective color intensity signals for a pixel for combining said at least one error signal with a different one of said respective color intensity signals for said pixel before it is divided by said dividing means, thereby obtaining an adjusted color intensity signal for said pixel which is divided by said dividing means.
Claim 4
Dependent Claim
120 words
A color encoder for encoding respective color intensity signals for each pixel to be displayed on a video display unit, comprising: means for dividing said respective color intensity signals for each pixel into first signals having a predetermined number of bits and error signals, said first signals being output as encoded color intensity signals; and means responsive to an error signal of at least one of said respective color intensity signals for a pixel for combining said at least one error signal with a different one of said respective color intensity signals for said pixel before it is divided by said dividing means, thereby obtaining an adjusted color intensity signal for said pixel which is divided by said dividing means.
Claim 5
Dependent Claim
34 words
An encoder as in claim 2, wherein said dividing means comprises a truncation circuit for each of said color intensity signals which truncates an input color intensity signal to said predetermined number of bits.
Claim 6
Dependent Claim
64 words
An encoder as in claim 2, wherein said dividing means comprises a dithering circuit for each of said color intensity signals which adds a predetermined number of dither bits from an input color intensity signal to aid predetermined number of bits of said input color intensity signal before limiting the sum to said predetermined number of bits output as said encoded color intensity signals.
Claim 7
Dependent Claim
50 words
An encoder as in claim 2, wherein said combining means comprises scaling means for scaling said at least one error signal and a summer for adding the scaled at least one error signal to said different one of said color intensity signals before it is input into said dividing means.
Claim 8
Dependent Claim
89 words
An encoder as in claim 5, wherein said at least one error signal comprises Green and Red error signals and said different one of said color intensity signals comprises a Blue signal, said scaling means respectively scaling said Green error signal by a value approximately equal to C G /C B and said Red error signal by a value approximately equal to C R /C B , where C G , C R and C B are determined from the luminance equation Y=C G ·G+C R ·R+C B ·B.
Claim 9
Dependent Claim
24 words
An encoder as in claim 6, wherein C G /C B is approximated by 5 and C R /C B is approximated by 2.5.
Claim 10
Dependent Claim
153 words
A color graphics system for displaying respective color intensity signals for each pixel of a video display unit, comprising: means for calculating said respective color intensity signals for each pixel said video display unit; means for encoding said respective color intensity signals at each pixel of said video display unit in accordance with the intensities of the other respective color intensity signals for that pixel so as to minimize visible luminance artifacts in a displayed image as a result of encoding, whereby an error signal of at least one of said respective color intensity signals for a pixel is combined with a different one of said respective color intensity signals for said pixel prior to outputting the respective encoded color intensity signals; memory means for storing the encoded outputs of said encoding means; and color look-up means for converting said encoded outputs to color intensity signals for display on said video display unit.
Claim 11
Dependent Claim
153 words
A color graphics system for displaying respective color intensity signals for each pixel of a video display unit, comprising: means for calculating said respective color intensity signals for each pixel said video display unit; means for encoding said respective color intensity signals at each pixel of said video display unit in accordance with the intensities of the other respective color intensity signals for that pixel so as to minimize visible luminance artifacts in a displayed image as a result of encoding, whereby an error signal of at least one of said respective color intensity signals for a pixel is combined with a different one of said respective color intensity signals for said pixel prior to outputting the respective encoded color intensity signals; memory means for storing the encoded outputs of said encoding means; and color look-up means for converting said encoded outputs to color intensity signals for display on said video display unit.
Claim 12
Dependent Claim
34 words
A system as in claim 8, wherein said encoding means comprises a truncation circuit for each of said color intensity signals which truncates an input color intensity signal to a predetermined number of bits.
Claim 13
Dependent Claim
64 words
A system as in claim 8, wherein said encoding means comprises a dithering circuit for each of said color intensity signals which adds a predetermined number of dither bits from an input color intensity signal to a predetermined number of bits of said input color intensity signal before limiting the sum to said predetermined number of bits output as said encoded color intensity signals.
Claim 14
Dependent Claim
44 words
A system as in claim 8, wherein said encoding means comprises combining means for scaling said at least one error signal and for adding the scaled at least one error signal to said different one of said color intensity signals before it is encoded.
Claim 15
Dependent Claim
89 words
A system as in claim 11, wherein said at least one error signal comprises Green and Red error signals and said different one of said color intensity signals comprises a Blue signal, said combining means respectively scaling said Green error signal by a value approximately equal to C G /C B and said Red error signal by a value approximately equal to C R /C B , where C G , C R and C B are determined from the luminance equation Y=C G ·G+C R ·R+C B ·B.
Claim 16
Dependent Claim
24 words
A system as in claim 12, wherein C G /C B is approximated by 5 and C R /C B is approximated by 2.5.
Claim 17
Dependent Claim
33 words
A system as in claim 12, wherein a bias towards Blue as a result of said scaling is offset by adjusting the values stored in said color look-up means to compensate said bias.
Claim 18
Independent Claim
95 words
A method of encoding respective color intensity signals for each pixel to be displayed on a video display unit, comprising the steps of: separately encoding the respective color intensity signals for each pixel of said video display unit; and adjusting, prior to said encoding step, the intensities of the respective color intensity signals at each pixel in accordance with the intensities of the other respective color intensity signals for that pixel so as to minimize visible luminance artifacts in the displayed image as a result of the encoding of each pixel in said encoding step.
Claim 19
Independent Claim
95 words
A method of encoding respective color intensity signals for each pixel to be displayed on a video display unit, comprising the steps of: separately encoding the respective color intensity signals for each pixel of said video display unit; and adjusting, prior to said encoding step, the intensities of the respective color intensity signals at each pixel in accordance with the intensities of the other respective color intensity signals for that pixel so as to minimize visible luminance artifacts in the displayed image as a result of the encoding of each pixel in said encoding step.
Claim 20
Dependent Claim
105 words
A method as in claim 15, wherein said adjusting step comprises the steps of: separately precomputing the intensity values of the respective encoded color intensity signals for each pixel to be displayed; calculating respective error signals for each pixel introduced by said encoding step; adjusting the intensities of the respective color intensity signals at each pixel in accordance with the intensities of the other respective color intensity signals for that pixel so as to minimize visible luminance artifacts in the displayed image as a result of the respective error signals; and inputting said adjusted color intensity signals into encoding means for performing said encoding step.
Claim 21
Dependent Claim
62 words
A method as in claim 16, wherein said color intensity signals are adjusted in said adjusting step by adjusting one color intensity signal for a pixel by an amount which offsets the error signals of the other color intensity signals for said pixel, thereby reducing the error in the luminance value of the displayed image as a result of the error signals.
Claim 22
Dependent Claim
20 words
A method as in claim 16, wherein said encoding step comprises the step of truncating the input color intensity signals.
Claim 23
Dependent Claim
22 words
A method as in claim 16, wherein said encoding step comprises the step of dithering the input color intensity signals during encoding.
Claim 24
Independent Claim
111 words
A method of encoding respective color intensity signals for each pixel to be displayed on a video display unit, comprising the steps of: dividing said respective color intensity signals for each pixel of said video display unit into first signals having a predetermined number of bits and error signals; separately combining at each pixel of said video display unit at least one error signal of said respective color intensity signals for a pixel with a different one of said respective color intensity signals for said pixel before it is divided in said dividing step, thereby obtaining an adjusted color intensity signal; and outputting said first signals as encoded color intensity signals.
Claim 25
Independent Claim
111 words
A method of encoding respective color intensity signals for each pixel to be displayed on a video display unit, comprising the steps of: dividing said respective color intensity signals for each pixel of said video display unit into first signals having a predetermined number of bits and error signals; separately combining at each pixel of said video display unit at least one error signal of said respective color intensity signals for a pixel with a different one of said respective color intensity signals for said pixel before it is divided in said dividing step, thereby obtaining an adjusted color intensity signal; and outputting said first signals as encoded color intensity signals.
Claim 26
Dependent Claim
26 words
A method as in claim 20, wherein said dividing step comprises the step of truncating an input color intensity signal to said predetermined number of bits.
Claim 27
Dependent Claim
57 words
A method as in claim 20, wherein said dividing step comprises the steps of adding a predetermined number of dither bits from an input color intensity signal to said predetermined number of bits of said input color intensity signal and then limiting the sum to said predetermined number of bits output as said encoded color intensity signals.
Claim 28
Dependent Claim
47 words
A method as in claim 20, wherein said combining step comprises the steps of scaling said at least one error signal and adding the scaled at least one error signal to said different one of said color intensity signals before it is divided in said dividing step.
Claim 29
Dependent Claim
96 words
A method as in claim 23, wherein said at least one error signal comprises Green and Red error signals and said different one of said color intensity signals comprises a Blue signal, said Green error signal being scaled in said scaling step by a value approximately equal to C G /C B and said Red error signal being scaled in said scaling step by a value approximately equal to C R /C B , where C G , C R and C B are determined from the luminance equation Y=C G ·G+C R ·R+C B ·B.
Claim 30
Dependent Claim
28 words
A method as in claim 24, wherein C G /C B is approximated by 5 and C R /C B is approximated by 2.5 in said scaling step.
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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) | 1995-12-08 | 1996-06-08 | 1996-12-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-12-08 | 2000-06-08 | 2000-12-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-12-08 | 2004-06-08 | 2004-12-08 | $7700.00 | Window Closed / Lapsed |