Qian Xu Lin

US Patent:

6791718, Sep 14, 2004

Filed:

Jun 14, 2000

Appl. No.:

09/594200

Inventors:

Jan P. Allebach - Lafayette IN
Qian Lin - Santa Clara CA

Assignee:

Hewlett-Packard Development Company, L.P. - Houston TX

International Classification:

H04N 1405

US Classification:

358 313, 358 317, 358534, 382237

Abstract:

A method and system for generating dither matrices for halftone printing. The design of the dither matrices involves modifying a human visual system model cost function to be color-blind and the addition of a cluster cost function. The cluster fluctuation function has a clustering factor for specify the clustering effect in the halftone image. The clustering factor is preferably gray-level dependent and may be implemented with a look-up table that specifies a clustering factor for each specific gray level. The cluster fluctuation function may optionally include a structure suppression term for suppressing the formation of long horizontal structures or long vertical structures. The structure suppression term includes a symmetry factor for specifying the symmetry of the cluster cost function. The symmetry factor is preferably gray-level dependent and may be implemented with a look-up table that specifies a symmetry factor for each specific gray level.

US Patent:

6829063, Dec 7, 2004

Filed:

Jun 14, 2000

Appl. No.:

09/594235

Inventors:

Jan P. Allebach - Lafayette IN
Qian Lin - Palo Alto CA

Assignee:

Hewlett-Packard Development Company, L.P. - Houston TX

International Classification:

G06K 1500

US Classification:

358 313, 358 316, 358534, 358535

Abstract:

A method and system for jointly designing at least two sets of dither matrices. First, a mosaic color tile is generated for a first concentration level according to a design tile map. The mosaic color tile includes at least a first color tile and a second color tile where each color tile has a color tile concentration level (CTCL) and a color tile number (CTN). Second, a color fluctuation metric is performed on the mosaic color tile. Next, the pixels in the first color tile are modified by an operation (e. g. , a swap operation) while maintaining the first concentration level. Then, a color fluctuation metric is re-calculated on the mosaic color tile with all first color tiles being replaced with the modified first color tile (i. e. , everywhere the first color tile appears in the mosaic color tile as specified by the design tile map). Performing the step of modifying the color tiles and re-calculating the color fluctuation metric for the modified mosaic tile until the metric is below a predetermined metric level.

US Patent:

7031025, Apr 18, 2006

Filed:

Aug 23, 2000

Appl. No.:

09/645790

Inventors:

Zhen He - West Lafayette IN, US
Charles A. Bouman - West Lafayette IN, US
Qian Lin - Santa Clara CA, US

Assignee:

Hewlett-Packard Development Company, L.P. - Houston TX

International Classification:

H04N 1/40

US Classification:

358 309, 358 311, 358 312

Abstract:

A combined dot density and size modulation system uses dispersed dot halftoning in conjunction with dot size modulation to produce a halftone image in which both the density and size of the dots are modulated to control overall gray level. The dot density and size modulation system offers advantages over pure dot density modulation systems or pure dot size modulation systems because it allows an extra degree of flexibility which can be used to increase the visual quality of the halftoned pattern and/or increase the robustness of the halftoning to printer artifacts and variations. An input pixel value is used to independently produce a dot density value and a dot size value. The dot density value and dot size values may be obtained from, e. g. , look up tables that have been optimized for print quality and printer stability. Dispersed dot halftoning is used to provide a halftone value for the desired pixel location using the dot density value.

US Patent:

20130259374, Oct 3, 2013

Filed:

Mar 29, 2012

Appl. No.:

13/433948

Inventors:

Lulu He - Evanston IL, US
Feng Tang - Mountain View CA, US
Qian Lin - Santa Clara CA, US

International Classification:

G06K 9/34

US Classification:

382173

Abstract:

In one implementation, an image segmentation system defines a first discriminative classifier and a second discriminative classifier. The first discriminative classifier is associated with a first segment of an object in an image based on a first foreground sample region of the image and a first background sample region of the image. The second discriminative classifier is associated with a second segment of the object based on a second foreground sample region of the image and a second background sample region of the image. The image segmentation system then identifies at least a portion of the first segment using the first discriminative classifier and at least a portion of the second segment using the second discriminative classifier.

US Patent:

58127445, Sep 22, 1998

Filed:

Apr 30, 1996

Appl. No.:

8/641304

Inventors:

Jan P. Allebach - Lafayette IN
Qian Lin - Santa Clara CA

Assignee:

Hewlett Packard Company - Palo Alto CA

International Classification:

H04N 152

US Classification:

395109

Abstract:

The present invention provides a system and method for generating halftone patterns. Typically the generated halftone patterns are used for generating dither matrices to halftone a image with improved visual quality. The steps for generating a plurality of color halftone patterns include: defining a color path from a color concentration level p to a color concentration level q; and generating a halftone patterns f. sub. j for each color concentration level j along the defined color path. After the halftone pattern f. sub. j is generated for the color concentration level j, the color fluctuation of the halftone pattern f. sub. j is minimized. A key contribution of the current invention is the decomposition of a color halftone pattern which occurs during the step of minimizing the color fluctuation for halftone pattern f. sub. j, and which allows simultaneous optimization of underlying color halftone patterns. After the step of minimizing the halftone pattern f. sub.