US 5,291,310 A · Screen generation for halftone screening of images

Abstract

A halftone screen pattern generation system for computing halftone screened images with rotated screens including multiple angle and ruling combinations, including irrational tangent angles, is disclosed. A screen pattern is generated by storing a plurality of strips from an ideal angled screen pattern, and then concatenating a sequence comprising a selected order of the plurality of strips in a sequence. The error between the actual generated screen and ideal desired screen is computed. Each subsequent strip is selected from the plurality of strips so as to reduce the accumulated error. In one embodiment, a screen pattern is generated by storing one strip of an ideal angled screen pattern, and then concatenating a selected sequence comprising the strip and substrips of the strip. In accordance with another aspect of the present invention, the measure of error between the actual generated screen and the ideal angled screen is the length of a vector in a transformed UV space between the actual screen sample point and the idealized screen sample point. The error is determined by vector addition of the accumulated error, from strip to strip, which is added to the present error contribution from the present strip.

Claims32

Dependent claims

A method for generating a halftone screened image from an original image, said method comprising:

storing a plurality of distinct strips, each of said plurality of distinct strips representing a different portion of an ideal angled screen pattern;
concatenating ones of said plurality of distinct strips in a sequence forming a generated screen pattern;
and
screening said original image with said generated screen pattern to form said halftone screened image.

1 more element

A method for generating a halftone screened image from an original image, said method comprising:

storing a plurality of strips, each of said plurality of strips representing a portion of an ideal angled screen pattern;
concatenating ones of said plurality of strips in a sequence forming a generated screen pattern;
and
screening said original image with said generated screen pattern to form said halftone screened image,
where said step of concatenating ones of said plurality of strips in a sequence forming a screen pattern further comprises:
computing an error function based on the difference between the generated screen pattern and an ideal desired screen pattern;
and
selecting a next selected one of said plurality of strips in said sequence so that said error function of one of said plurality of strips combined with the error function of said selected next of said plurality of strips produces the least combined error.

5 more elements

A method for generating a halftone screened image from an original image, said method comprising:

storing a plurality of strips, the first of said plurality of strips representing a portion of an ideal angled screen pattern, and the remainder of said plurality of strips being one or more substrips of said first strip;
concatenating ones of said plurality of strips in a sequence forming a generated screen pattern;
and
screening said original image with said generated screen pattern to form said halftone screened image,
where said step of concatenating ones of said plurality of strips in a sequence forming a screen pattern further comprises:
computing an error function based on the difference between the generated screen pattern and an ideal desired screen pattern;
and
selecting a next selected one of said plurality of strips in said sequence so that said error function of one of said plurality of strips combined with the error function of said selected next of said plurality of strips produces the least combined error.

5 more elements

An apparatus for generating a halftone screened image from an original image, said apparatus comprising:

means for storing a plurality of strips, each of said plurality of strips representing a portion of an ideal angled screen pattern;
means for concatenating ones of said plurality of strips in a sequence forming a generated screen pattern;
and
means for screening said original image with said generated screen pattern to form said halftone screened image,
where said means for concatenating ones of said plurality of strips in a sequence forming a screen pattern further comprises:
means for computing an error function based on the difference between the generated screen pattern and an ideal desired screen pattern;
and
means for selecting a next selected one of said plurality of strips in said sequence so that said error function of one of said plurality of strips combined with the error function of said selected next of said plurality of strips produces the least combined error.

5 more elements

An apparatus for generating a halftone screened image from an original image, said apparatus comprising:

means for storing a plurality of strips, the first of said plurality of strips representing a portion of an ideal angled screen pattern, and the remainder of said plurality of strips being one or more substrips of said first strip;
means for concatenating ones of said plurality of strips in a sequence forming a generated screen pattern;
and
means for screening said original image with said generated screen pattern to form said halftone screened image,
where said means for concatenating ones of said plurality of strips in a sequence forming a screen pattern further comprises:
means for computing an error function based on the difference between the generated screen pattern and an ideal desired screen pattern;
and
means for selecting a next selected one of said plurality of strips in said sequence so that said error function of one of said plurality of strips combined with the error function of said selected next of said plurality of strips produces the least combined error.

5 more elements

Dependencies are inferred from the claim text.

Screen generation for halftone screening of images

Life of this patent

Screen generation for halftone screening of images

Life of this patent

Abstract

Claims32