EP0525996A2
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EP
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Method of resolution conversion
Assignee: Xerox Corp
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Filing: 1992-07-01
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Granted: —
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Expires: 2012-07-01
Abstract
Abstract A method of resolution conversion for use in a system (10) of the type capable of manipulating digital images represented by a plurality of original image pixels is provided. In the preferred embodiment, the system (10) has a memory (100) for storing images and an image output terminal (14). Additionally, the method includes a step of deriving an intensity value (Z) for a selected output pixel (108) in a set of (106) output pixels from a plurality of input pixels (104) in a set of input pixels, each of the plurality of input pixels (104) having a corresponding intensity value (I) contributing to the intensity value (Z) of the selected output pixel. The step of deriving the intensity value (Z) of the selected output pixel preferably comprises the steps of mapping, in the memory, the set of output pixels to the set of input pixels so that each of the plurality of input pixels (104) is adjacent the selected output pixel (108), as well as reading the plurality of input pixels (104) from the memory. After determining a correlation value for each of the plurality of input pixels (104) with a correlation function (W), the correlation values of the plurality of input pixels (104) can be summed with the corresponding respective intensity values of the plurality of input pixels (104) to obtain the intensity value (Z) of the selected output pixel (108).
Inventors
- 👤 John O. Walker
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 06:34
CPC Classifications
G; G06; G06T; G06T3/00; G06T3/40
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
225 words
A method of resolution conversion for use in a system (10) of the type capable of manipulating digital images represented by a plurality of original image pixels, the system (10) having a memory (100) for storing images and means (14) for outputting the images, the method characterised by deriving an intensity value (Z) for a selected output pixel (108) in a set (106) of output pixels from a plurality of input pixels (104) in a set (102) of input pixels, each of the plurality of input pixels (104) having a corresponding intensity value (I) contributing to the intensity value (Z) of the selected output pixel (108), the step of deriving the intensity value (Z) of the selected output pixel (108) comprising the steps of: mapping, in the memory (100), the set (106) of output pixels to the set (102) of input pixels so that each of the plurality of input pixels (104) is adjacent the selected output pixel (108); reading the plurality of input pixels (104) from the memory (100); determining a correlation value for each of the plurality of input pixels (104) with a correlation function (W), and summing the correlation values of the plurality of input pixels (104) with the corresponding respective intensity values of the plurality of input pixels (104) to obtain the intensity value (Z) of the selected output pixel (108).
Claim 2
Independent Claim
225 words
A method of resolution conversion for use in a system (10) of the type capable of manipulating digital images represented by a plurality of original image pixels, the system (10) having a memory (100) for storing images and means (14) for outputting the images, the method characterised by deriving an intensity value (Z) for a selected output pixel (108) in a set (106) of output pixels from a plurality of input pixels (104) in a set (102) of input pixels, each of the plurality of input pixels (104) having a corresponding intensity value (I) contributing to the intensity value (Z) of the selected output pixel (108), the step of deriving the intensity value (Z) of the selected output pixel (108) comprising the steps of: mapping, in the memory (100), the set (106) of output pixels to the set (102) of input pixels so that each of the plurality of input pixels (104) is adjacent the selected output pixel (108); reading the plurality of input pixels (104) from the memory (100); determining a correlation value for each of the plurality of input pixels (104) with a correlation function (W), and summing the correlation values of the plurality of input pixels (104) with the corresponding respective intensity values of the plurality of input pixels (104) to obtain the intensity value (Z) of the selected output pixel (108).
Claim 3
Dependent Claim
45 words
A method as claimed in claim 1, characterised in that the means (14) for outputting the images is a rastor output scanning device (14) selectively controlled dependent on said intensity value (Z) of the selected output pixel (108) for selectively discharging a photoreceptor member (50).
Claim 4
Dependent Claim
23 words
A method as claimed in claim 1 or claim 2, characterised in that the correlation function (W) is a Gaussian-like correlation function (W).
Claim 5
Dependent Claim
21 words
A method as claimed in claim 3, characterised in that the Gaussian-like correlation function (W) is characterized by the following expression:
Claim 6
Independent Claim
50 words
A method as claimed in any one of claims 1 to 4, characterised by designating a pivot point (X c , Y c ) for the selected output pixel (108) and disposing the centers of the plurality of input pixels (104) substantially within a window centered about the pivot point.
Claim 7
Dependent Claim
23 words
A method as claimed in claim 5, characterised by varying the size of the window as a function of the correlation function (W).
Claim 8
Dependent Claim
45 words
A method as claimed in claim 5 or claim 6, characterised in that the step of disposing the centers of the plurality of input pixels (104) comprises the step of disposing the centers of the plurality of input pixels (104) substantially within an ellipse (115).
Claim 9
Independent Claim
23 words
A method as claimed in any one of claims 5 to 7, characterised by the step of optimizing the size of the window.
Claim 10
Independent Claim
261 words
A method of resolution conversion for use in a system (10) of the type capable of manipulating digital images represented by a plurality of original image pixels, the system (10) having a memory (100) for storing images and means (14) for outputting the images, the method characterised by deriving an intensity value (Z) for a selected output pixel (108) in a set (106) of output pixels from a plurality of input pixels (104) in a set (102) of input pixels, each of the plurality of input pixels (104) having a corresponding intensity value (I) contributing to the intensity value (Z) of the selected output pixel (108), the step of deriving the intensity value (Z) of the selected output pixel (108) comprising the steps of: mapping, in a memory (100), the set (106) of output pixels to the set (102) of input pixels so that each of the plurality of input pixels (104) is adjacent the selected output pixel (108); reading the plurality of input pixels (104) from the memory (100); forming a multi-bit index word from the corresponding intensity values (I) of the plurality of input pixels (104); providing a table having a plurality of preselected reference words and intensity values respectively assigned thereto, the plurality of preselected reference words and respectively assigned intensity values being ordered in a sequence, the sequence varying in accordance with a correlation function (W); and matching the multi-bit index word with one of the preselected reference words and its respectively assigned intensity value to determine the intensity value (Z) of the selected output pixel (108).
Claim 11
Independent Claim
261 words
A method of resolution conversion for use in a system (10) of the type capable of manipulating digital images represented by a plurality of original image pixels, the system (10) having a memory (100) for storing images and means (14) for outputting the images, the method characterised by deriving an intensity value (Z) for a selected output pixel (108) in a set (106) of output pixels from a plurality of input pixels (104) in a set (102) of input pixels, each of the plurality of input pixels (104) having a corresponding intensity value (I) contributing to the intensity value (Z) of the selected output pixel (108), the step of deriving the intensity value (Z) of the selected output pixel (108) comprising the steps of: mapping, in a memory (100), the set (106) of output pixels to the set (102) of input pixels so that each of the plurality of input pixels (104) is adjacent the selected output pixel (108); reading the plurality of input pixels (104) from the memory (100); forming a multi-bit index word from the corresponding intensity values (I) of the plurality of input pixels (104); providing a table having a plurality of preselected reference words and intensity values respectively assigned thereto, the plurality of preselected reference words and respectively assigned intensity values being ordered in a sequence, the sequence varying in accordance with a correlation function (W); and matching the multi-bit index word with one of the preselected reference words and its respectively assigned intensity value to determine the intensity value (Z) of the selected output pixel (108).
Claim 12
Dependent Claim
45 words
A method as claimed in claim 9, characterised in that the means (14) for outputting the images is a rastor output scanning device (14) selectively controlled dependent on said intensity value (Z) of the selected output pixel (108) for selectively discharging a photoreceptor member (50).
References Cited (Backward Citations)
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