EP0895408A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Color halftone error-diffusion with local brightness variation reduction
Assignee: HP Inc
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Filing: 1998-07-27
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Granted: —
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Expires: 2018-07-27
Abstract
Abstract Higher quality is obtained with error diffusion algorithms such as the Floyd Steinberg error-diffusion algorithm used in halftoning methods in which quantization errors are diffused to "future" pixels, by adding a Minimum Brightness Variation Criterion (MBVC) to the design rules of color error-diffusion halftoning methods. Halftone values are constrained to be vertices of a Minimum Brightness Variation Quadruple (MBVQ) associated with each pixel of the color image being processed.
Inventors
- 👤 Doron Shaked
- 👤 Nur Arad
- 👤 Andrew Fitzhugh
- 👤 Irwin Sobel
- 👤 Michael D. Mcguire
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 12:20
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/46; H04N1/52
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
49 words
A halftoning apparatus for a color image, the apparatus
comprising: means for locally limiting a set of halftone colors, the set being limited
so as to minimize dot-noticeability metrics; and means for locally applying the limited set of halftone colors to the
color image to yield a halftone image.
Claim 2
Dependent Claim
20 words
An apparatus as set forth in claim 1, wherein the dot-noticeability
metrics are based on a Human Visual system model.
Claim 3
Dependent Claim
18 words
An apparatus as set forth in claim 1, that uses Minimum
Perceivable Noise Variation as the dot-noticeability metrics.
Claim 4
Dependent Claim
16 words
An apparatus as set forth in claim 1, that uses Brightness
Variation as the dot-noticeability metrics.
Claim 5
Dependent Claim
48 words
A halftoning process for a color image, the process comprising
the steps of: locally limiting a set of halftone colors, the set being limited so as to
minimize dot-noticeability metrics; and locally applying the limited set of halftone colors to the color image to
yield a halftone image.
Claim 6
Dependent Claim
110 words
An error-diffusion halftone processor for a color image, the
processor comprising: an accumulated error summer to add input RGB to an accumulated
error; a minimum brightness variation quadruple (MBVQ) computer to
determine a MBVQ for a pixel within the color image; a vertex selector to find a vertex of the MBVQ closest to the pixel
and to assign the vertex color to a color halftone at a location
corresponding to the pixel; a quantization error summer to find quantization error based upon
using the vertex; a distributer to distribute the quantization error to future pixels; and a buffer to store quantization error for the future pixels of the color
image.
Claim 7
Dependent Claim
19 words
The processor as set forth in claim 6. wherein the MBVQ
computer finds the MBVQ for the input pixel.
Claim 8
Dependent Claim
31 words
The processor as set forth in claim 6. wherein the MBVQ
computer finds the MBVQ for the pixel using the pixel value when
combined with an error term for the pixel.
Claim 9
Dependent Claim
86 words
An error-diffusion halftone process for a color image
comprising the steps of: adding input RGB to an accumulated error; determining a minimum brightness variation quadruple (MBVQ) for
a pixel within the color image; finding a vertex of the MBVQ closest to the pixel and assigning the
vertex color to a color halftone at a location corresponding to the pixel; finding quantization error based upon using the vertex; distributing the quantization error to future pixels; and storing quantization error for the future pixels of the color image.
Claim 10
Dependent Claim
97 words
An error-diffusion halftone processor for a color image, the
processor comprising: means for adding input RGB to an accumulated error; means for determining a minimum brightness variation quadruple
(MBVQ) for a pixel within the color image; means for finding a vertex of the MBVQ closest to the pixel and
assigning the vertex color to a color halftone at a location corresponding to
the pixel; means for finding quantization error based upon using the vertex; means for distributing the quantization error to future pixels; and means for storing quantization error for the future pixels of the color
image.
References Cited (Backward Citations)
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