Hewlett-packard Company

Stratasys, Inc.

Nur Arad

Doron Shaked

Andrew E Fitzhugh

Irwin Sobel

Qian Lin

Izhak Baharav

Blake Zachary Courter

Michael D McGuire

Ore Shtalrid

Stephen Demai

Yossi Koren

A method of rendering data for addressable dispensing of material over a working surface, comprises: receiving input image data arranged grid-wise over a plurality of picture-elements; generating an initial map describing a distance field and having a plurality of map-elements each storing distance information corresponding to one picture-element; for each picture-element of at least a portion of the picture-elements: linearly scanning the map independently along a first axis and along a second axis, and updating a respective map-element based on values of map-elements visited during the scan. The distance field can include distances defined perpendicularly to the working surface.

Method and system for rendering data for addressable dispensing

A pixel color in an image can be represented by a dot color in a dot pattern as follows. A subset of a limited set of display colors is selected. The subset has N display colors that can render a solid color patch of the pixel color. The colors of the subset correspond to vertices of a simplex in the color space. The simplex has (N&minus;1) dimensions. A point operation is then performed to select one of the vertices of the simplex and thereby select the dot color of the subset color corresponding to the selected vertex. Consequently, a solid patch of the pixel color can be rendered by a dot pattern having no more than N different colors. The dot pattern can be displayed by an imaging device such as an inkjet printer, which has a limited set of display colors.

Apparatus and method of performing dithering in a simplex in color space

Error diffusion algorithms such as the celebrated Floyd Steinberg error-diffusion algorithm are high-performance halftoning methods in which quantization errors are diffused to 'future' pixels. Originally intended for grayscale images, they are traditionally extended to color images by error-diffusing each of the three color planes independently (separable error-diffusion). Adding a design rule which is based on certain characteristics of human color perception to the error-diffusion paradigm results in a color halftoning algorithm having output of considerably higher quality when compared to separable error-diffusion. These benefits are achieved by adding the Minimum Brightness Variation Criterion (MBVC) to the design rules of color error-diffusion halftoning methods. Halftone values are constrained to be vertices of a Minimum Brightness Variation Quadruple (MBVQ) associated with each pixel of the color image being processed. The algorithm presented requires no additional memory and entails a reasonable increase in run-time.

Color halftone error-diffusion with local brightness variation reduction

Current methodologies for color image halftoning produce prominent halftoning noise. Brightness variations between color dots placed at neighboring locations are a primary cause of color halftone noise. To correct this flaw, an Ink Relocation Postprocess to halftoning algorithms relocates ink drops between neighboring drop locations in order to reduce local brightness variations. Due to the intrinsic blurring side-effect of ink relocation, some enhancement may be desired. Two application-specific enhancement procedures are presented. In the first enhancement, ink relocation is suppressed in areas of fine detail. In the second enhancement, edge sharpening is performed after ink relocation.

Ink relocation for color halftones

Growing community of inventors

Tel Aviv, Israel

Nur Arad