Qian Lin

US Patent:

6335989, Jan 1, 2002

Filed:

Jul 31, 1998

Appl. No.:

09/127927

Inventors:

Qian Lin - Santa Clara CA

Assignee:

Hewlett-Packard Company - Palo Alto CA

International Classification:

G06K 1500

US Classification:

382260, 382251

Abstract:

A method of generating a halftone image from a gray scale image using stochastic halftoning printing screens. A clustered dot stochastic screen is prepared for multiple gray levels by using a first filter at the lightest gray levels, switching to a donut filter at gray levels after a selected transition level, optionally using the donut filter at all gray levels. The donut filter has its maxima away from the current pixel.

US Patent:

6600573, Jul 29, 2003

Filed:

Sep 1, 1998

Appl. No.:

09/144724

Inventors:

Doran Shaked - Haifa, IL
Izhak Baharav - Givat-Ela, IL
Qian Lin - Santa Clara CA

Assignee:

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

International Classification:

H04N 146

US Classification:

358 19, 358 11, 358535, 358539

Abstract:

A color image is converted into a dot pattern for display by a color printer. The image is separated into Cyan, Magenta and Yellow color planes; a dither matrix is applied to the Cyan plane; an inverse of the dither matrix is applied to the Magenta plane; and either the dither matrix or the inverse dither matrix is applied to the Yellow plane.

US Patent:

6621595, Sep 16, 2003

Filed:

Nov 1, 2000

Appl. No.:

09/704358

Inventors:

Jian Fan - Cupertino CA
Daniel Tretter - Palo Alto CA
Qian Lin - Santa Clara CA
Neerja Raman - Los Altos Hills CA

Assignee:

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

International Classification:

H04N 1409

US Classification:

358 326, 358 327, 358462, 358463, 358464, 358532, 358 21, 382167, 382172, 382266, 382275

Abstract:

A system and method for enhancing scanned document images utilizes an estimated background luminance of a given digital image to remove or reduce visual âsee-throughâ noise. The estimated background luminance is dependent on the luminance values of the edges pixels of detected text edges of the image. In one embodiment, the estimated background luminance is generated using only the edge pixels that are on the lighter side of the detected edges. In addition to the see-through removal, the system and method may further enhance the scanned document images by removing color fringes and sharpening and/or darkening edges of text contained in the images.

US Patent:

6724501, Apr 20, 2004

Filed:

Jun 22, 2001

Appl. No.:

09/885946

Inventors:

Clayton B. Atkins - Mountain View CA
Daniel R. Tretter - Palo Alto CA
Qian Lin - Santa Clara CA

Assignee:

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

International Classification:

H04N 1405

US Classification:

358 317, 358 313, 358534, 358535

Abstract:

An apparatus and method for dither matrix design for color halftoning using dispersed dot clusters where the dot cluster centers are arranged in a homogeneous and isotropic pattern, in order avoid the moirà effect. The method requires that the size of the array and the number of dot seeds that will be in the array be predetermined.

US Patent:

6760126, Jul 6, 2004

Filed:

Jun 20, 2000

Appl. No.:

09/597862

Inventors:

Kong Kritayakirana - Sunnyvale CA
Daniel R. Tretter - Palo Alto CA
Qian Lin - Santa Clara CA

Assignee:

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

International Classification:

H04N 1405

US Classification:

358 21, 358 315, 358 314

Abstract:

Methods and apparatus for adaptive halftoning for accommodating a mix of high and low visual activity are provided. Accommodations for white gap reduction and variable darkening are provided for print engine imperfections. A method includes the steps of thresholding a selected pixel of a source image to generate a first dithered output signal, L. The selected pixel is also thresholded to generate a second dithered output signal, S. A weighted combination of the first and second dithered output signals is generated in accordance with at least one of an edge activity indicator parameter and a mix suppression parameter. The parameters are calculated from pixel values within a contiguous region of the source image including the selected pixel. The first and second dithered output signals correspond to large and small threshold matrices in one embodiment. The second dithered output signal may be boosted using a variable darkening parameter, , to accommodate isolated dot gain problems before being combined.

US Patent:

6778299, Aug 17, 2004

Filed:

Mar 9, 2001

Appl. No.:

09/802401

Inventors:

Qian Lin - Santa Clara CA
Daniel Tretter - Palo Alto CA
Jian Fan - Cupertino CA
Clayton Brian Atkins - Mountain View CA

Assignee:

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

International Classification:

H04N 1405

US Classification:

358 303, 358 305, 358 316, 358 317, 358 319, 358 322, 358 323, 358 326

Abstract:

A method and system for halftoning images that uses error diffusion with partial dots is provided. First, an input picture element (input pixel) that has a picture level (e. g. , gray level) is received. Next, a reproducible gray level is generated based on the gray level of an input pixel. Then, a corrected gray level is generated based on the gray level of an input pixel and an error amount (e. g. , error propagated or diffused from adjacent areas or pixels). A determination is made whether the corrected gray level is in a predetermined relationship with a threshold. When the corrected gray level is in a predetermined relationship with the threshold, the reproducible gray level (i. e. , partial dot size) is provided as output. When the corrected gray level is not in a predetermined relationship with the threshold, a zero value is provided as output. It is noted that the output gray level and the corrected gray level are provided to an error distribution module for calculating an error and for propagating or diffusing the error to future adjacent areas or pixels.

US Patent:

6977679, Dec 20, 2005

Filed:

Apr 3, 2001

Appl. No.:

09/825739

Inventors:

Daniel R. Tretter - Palo Alto CA, US
Qian Lin - Santa Clara CA, US

Assignee:

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

International Classification:

H04N005/76

US Classification:

3482312, 3482313, 3482315, 382156, 382159, 382227, 703 20

Abstract:

A method and system for categorizing non-textual subject data, such as digital images, content-based data and meta-data to determine outcomes of classification tasks. The meta-data is indicative of the operational conditions of a recording device during the capturing of the content-based data. For example, the non-textual subject data may be a digital image captured by a digital camera, and the meta-data may include automatic gain setting, film speed, shutter speed, aperture/lens index, focusing distance, date and time, and flash/no flash operation. The subject image is tagged with selected classifiers by subjecting the image to a series of classification tasks utilizing both content-based data and meta data to determine classifiers associated with the subject image.

US Patent:

7053939, May 30, 2006

Filed:

Oct 17, 2001

Appl. No.:

09/982620

Inventors:

Qian Lin - Santa Clara CA, US
Daniel Tretter - San Jose CA, US
Jian Fan - Cupertino CA, US

Assignee:

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

International Classification:

H04N 5/262

US Classification:

348239

Abstract:

A method and system for capturing images. First, a preview image of a scene is captured. Next, an automatic determination is made whether the scene is a document. When it is determined that the scene is a document, at least one camera control is set to a value that is tailored for document capture. The scene is then captured using the set camera controls. Image processing that is tailored for documents is then performed on the captured scene.