# US 5,706,099 A · Method and apparatus for generating serpentine halftone images

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- Number: US 5,706,099 A
- Document ID: US5706099A
- Status: Granted
- Kind: A
- Application number: 08/463,178
- Filed: 1995-06-05
- Granted: 1998-01-06
- Earliest claimed: 1995-06-05
- Assignees: Xerox Corporation
- Inventors: Douglas N. Curry
- Web page: https://patentgrep.com/patent/US5706099A

## CPC

- H04N 1/405: Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

An apparatus and method for producing a halftone image which generates halftone cells based on grayscale image data values. Each of the halftone cells is formed from serpentine dot patterns. The serpentine dot patterns form two separate arcs. The halftone cells are written onto a recording medium to produce the halftone image. Rotation of the halftone cells allows data to be encoded within each of the halftone cells without varying the tone of the image. The tone of the image may be controlled by selectively varying a thickness of the arcs within the halftone

## Claims

### Claim 1

An apparatus for producing a halftone image, comprising:
a halftone generator for generating halftone cells based on grayscale image data values, each of the halftone cells comprising serpentine dot patterns forming at least two separate arcs; and
an output device for writing the halftone cells on a recording medium to produce the halftone image, wherein each of the halftone cells has four sides, each of the two arcs having two end portions, each of the end portions intersecting a center portion of one of the four sides.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein a tone of the halftone image is independent of rotation of one halftone cell relative to adjacent halftone cells.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein each of the halftone cells has four sides, each of the arcs has two end portions and each of the end portions contacts end portions of the arcs of an adjacent one of the halftone cells at a center portion of the sides.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein the halftone generator varies a tone of the image by selectively varying a thickness of the arcs within individual ones of the halftone cells.

### Claim 5 (depends on 1)

The apparatus of claim 1, further comprising encoding means for encoding data within each of the halftone cells.

### Claim 6 (depends on 1)

The apparatus of claim 1, wherein the halftone image is a polychromatic halftone image.

### Claim 7 (depends on 5)

The apparatus of claim 5, wherein the encoding means comprises a pattern rotating device for rotating the halftone cells based on encoding data.

### Claim 8 (depends on 5)

The apparatus of claim 5, wherein the halftone image is a polychromatic halftone image.

### Claim 9 (depends on 7)

The apparatus of claim 7, wherein a rotational position of each of the halftone cells determines an encoded data value.

### Claim 10 (depends on 9)

The apparatus of claim 9, wherein the rotational position of the halftone cells does not affect a tone of the image.

### Claim 11

A method of producing a halftone image, comprising:
generating halftone cells based on grayscale image data values, each of the halftone cells comprising serpentine dot patterns forming at least two separate arcs; and
writing the halftone cells on a recording medium to produce the halftone image, wherein each of the halftone cells has four sides, each of the two arcs having two end portions, each of the end portions intersecting a center portion of one of the four sides.

### Claim 12 (depends on 11)

The method of claim 11 comprising rotating one halftone cell relative to adjacent halftone cells without affecting a tone of the halftone image.

### Claim 13 (depends on 11)

The method of claim 11, wherein each of the end portions contacts end portions of the arcs of an adjacent one of the halftone cells at a center portion of the sides.

### Claim 14 (depends on 11)

The method of claim 11, further comprising varying a tone of the image by selectively varying a thickness of the arcs within individual ones of the halftone cells.

### Claim 15 (depends on 11)

The method of claim 11, further comprising encoding data within each of the halftone cells.

### Claim 16 (depends on 11)

The method of claim 11, wherein the halftone image is a polychromatic halftone image.

### Claim 17 (depends on 15)

The method of claim 15, wherein encoding data within each of the halftone cells comprises rotating the halftone cells based on encoding data.

### Claim 18 (depends on 15)

The method of claim 15, wherein a rotational position of each of the halftone cells determines an encoded data value.

### Claim 19 (depends on 15)

The method of claim 15, wherein the halftone image is a polychromatic halftone image.

### Claim 20 (depends on 18)

The method of claim 18, wherein the rotational position of the halftone cells does not affect a tone of the image.