EP0303190A2
Expired / Lapsed
EP
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Method of forming halftone screen
Assignee: Fujifilm Holdings Corp
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Filing: 1988-08-04
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Granted: —
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Expires: 2008-08-04
Abstract
Abstract When converting a continuous-tone image into a halftone dot image based on halftone screen signals, a screen angle is defined as a rational tangent thereof to establish a basic periodic portion of the halftone screen signals, and the basic periodic portion is periodically generated to form a halftone screen which covers an entire scanned region of the continuous-tone image. Minimum unit dot data items determined by a screen angle and/or a dot resolution level are prepared, and the dot data items are generated in a sequence which is established based on said screen angle and/or said dot resolution level to constitute the basic periodic portion.
Inventors
- 👤 Osamu Fuji Photo Film Co. Ltd. Shimazaki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 05:26
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/405; H04N1/4055; H04N1/4058
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
110 words
A method of forming a halftone screen in converting a continuous-tone image into a halftone dot image based on halftone screen signals by defining a screen angle as a rational tangent thereof to establish a basic periodic portion of the halftone screen signals and periodically generating the basic periodic portion to cover an entire scanned region of the continuous-tone image, said method comprising the steps of: preparing minimum unit dot data items determined by a screen angle and/or a dot resolution level; and generating the dot data items in a sequence which is established based on said screen angle and/or said dot resolution level to constitute the basic periodic portion.
Claim 2
Independent Claim
110 words
A method of forming a halftone screen in converting a continuous-tone image into a halftone dot image based on halftone screen signals by defining a screen angle as a rational tangent thereof to establish a basic periodic portion of the halftone screen signals and periodically generating the basic periodic portion to cover an entire scanned region of the continuous-tone image, said method comprising the steps of: preparing minimum unit dot data items determined by a screen angle and/or a dot resolution level; and generating the dot data items in a sequence which is established based on said screen angle and/or said dot resolution level to constitute the basic periodic portion.
Claim 3
Dependent Claim
23 words
A method according to claim 1, wherein said basic periodic portion includes a dot composed of an integral number of dot data items.
Claim 4
Dependent Claim
37 words
A method according to claim 1, wherein said basic periodic portion is constructed by repeatedly generating successively an integral number of dot data items which are established based on the screen angle and/or the dot resolution level.
Claim 5
Dependent Claim
46 words
A method according to claim 1, wherein the dot data items are stored in memory means, said basic periodic portion being constructed by fetching the stored dot data items from said memory means in an address sequence which is established based on predetermined address conversion data.
Claim 6
Dependent Claim
40 words
A method according to claim 4, wherein desired dot data items are selected out of a plurality of dot data items which are established based on the screen angle and/or the dot resolution level and are stored in memory means.
Claim 7
Dependent Claim
45 words
A method according to claim 1, wherein the dot data items are arranged according to an algorithm which is defined based on the screen angle and/or the dot resolution level, so as to be converted into dot data items which constitute the basic periodic portion.
Claim 8
Dependent Claim
87 words
A method according to claim 6, wherein the dot data items represented by address signals X, Y are converted into dot data items represented by address signals x, y which are defined by: x = MOD(X + F(Y),N X ) y = MOD(Y,N Y ) where N X , N Y are the numbers of dot data items of the basic periodic portion in directions X, Y, respectively, F(Y) is an address offset number with respect to the address signal Y, and MOD is a modulo operator.
References Cited (Backward Citations)
No citation records indexed.
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