Claims
- 1. A machine method for generating a binarized image from an original image comprising steps of:
- generating an electronic representation of a random image as an array of random image pixels;
- generating electronic representations of a plurality of sets of dither cell threshold values;
- generating an electronic representation of the original image as an array of image pixels, each image pixel having a pixel density value;
- establishing a correspondence between original image pixels and positions within a macro-dither cell, said macro-dither cell having positions corresponding to a union of a plurality of dither cells;
- selecting a pixel from the random image, and based on the random value of the pixel from the random image, selecting one of the plurality of sets of dither cell threshold values;
- selecting one threshold value from the randomly selected set according to a position within the macro-dither cell that corresponds to the original image pixel;
- electronically replacing the density value of the image pixel with a binary value according to a predetermined relationship between the density value of the image pixel and the selected threshold value, thereby generating a binarized image.
- 2. A method as in claim 1 wherein the density values of the random image have a substantially uniform distribution over a region the size of a dither cell.
- 3. A method as in claim 1 wherein the density values of the random image have a substantially uniform distribution over a region the size of a macro-dither cell.
- 4. A method as in claim 1 wherein the density values of the random image have a substantially uniform distribution over a region of a size greater than a macro-dither cell.
- 5. A method as in claim 1 wherein a dither cell threshold value set has at least 8 threshold values.
- 6. A method as in claim 1 wherein the macro-dither cell has positions corresponding to a union of four dither cells.
- 7. A method as in claim 6 wherein the macro-dither cell has positions corresponding to four dither cells united in an arrangement which minimizes distances among dither cell centers.
- 8. A method as in claim 1 wherein a threshold value set has an organization corresponding to a substantially cross-shaped dither cell.
Priority Claims (3)
Number |
Date |
Country |
Kind |
1-103695 |
Apr 1989 |
JPX |
|
1-147229 |
Jun 1989 |
JPX |
|
1-157164 |
Jun 1989 |
JPX |
|
Parent Case Info
This is a division of application Ser. No. 7/512,258, filed Apr. 20, 1990, Pat. No. 5,201,013.
US Referenced Citations (14)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0272147 |
Jun 1988 |
EPX |
59-163959 |
Sep 1984 |
JPX |
Non-Patent Literature Citations (2)
Entry |
Klaus Koch, Untersuchung Der Wahrnehmbarkeit von Rasterungen bei Digitaler Wiedergabe von Halbtonbildern, May 28, 1984, pp. 1-A49. |
J. C. Stoffel, J. F. Moreland, A Survey of Electronic Techniques for Pictorial Image Reproduction, IEEE Transactions on Communications 1.COM-29 (1981) Dec., No. 12, pp. 1898-1925. |
Divisions (1)
|
Number |
Date |
Country |
Parent |
512258 |
Apr 1990 |
|