Image data processing apparatus

• US 5,073,966 A
• Filed: 07/09/1990
• Issued: 12/17/1991
• Est. Priority Date: 05/10/1983
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Sato, Hiroaki
• Primary Examiner(s): Moore, David K.
• Assistant Examiner(s): Mancuso, Joseph
• Application Number:
  US07/550,224
• Time in Patent Office: 526 Days
• Field of Search: 382/50, 382/56, 358/260, 358/283, 358/298, 358/261.1, 358/426, 358/462, 358/448, 358/455-457, 358/459, 358/429, 358/106
• US Class Current: 382/237
• CPC Class Codes: H04N 1/40087 Multi-toning, i.e. converting a continuous-tone signal for reproduction with more than two discrete brightnesses or optical densities, e.g. dots of grey and black inks on white paper

Abstract

An image data processing apparatus comprises output means for outputting image data for each pixel and compression means for compressing the image data supplied from the output means to image data of a predetermined number of bits. The compression means compresses the image data in accordance with a dot pattern having a predetermined number of tone levels.

Claims

1. An image data processing apparatus comprising:

input means for inputting image data of m bits for each pixel, each of the image data representing one of M tone levels (M≦

2^m);

generation means for generating position information relating to each pixel; and

conversion means for converting the image data input from said input means into code data of n bits (n<

m) for each pixel,

wherein the M tone levels are divided, with K threshold levels (K<

2ⁿ) into K+1 ranges which correspond to K+1 dot patterns each composed of plural dots, and the converted code data indicates one of the K+1 ranges in which the tone level represented by the image data is included, and

wherein the K threshold levels are varied in accordance with the position information generated by said generating means.

2. An image data processing apparatus according to claim 1, further comprising reproducing means for reproducing an image on the basis of the code data.

3. An image data processing apparatus according to claim 2, wherein said reproducing means reproduces a dot pattern in accordance with the code data.

4. An image processing apparatus according to claim 3, wherein said reproducing means comprises forming means for forming the dot pattern corresponding to the code data.

5. An image data processing apparatus according to claim 1, wherein said generation means includes a counter for determining a position of the image data.

6. An image data processing apparatus according to claim 1, further comprising storage means for storing the code data output from said conversion means.

7. An image data processing apparatus according to claim 1, further comprising

decoder means for forming image data on the basis of the code data.

8. An image processing apparatus according to claim 1, wherein said conversion means comprises memory means for storing therein the code data corresponding to the image data and the position information.

9. An image processing apparatus according to claim 8, wherein said memory means outputs the code data in accordance with the image data and the position information.

10. An image processing apparatus according to claim 1, wherein the dots constituting said dot pattern have plural tone levels.