Apparatus for converting and processing input bi-level image data and faithfully rendering tones, colors, and edges

• US 5,283,664 A
• Filed: 10/09/1991
• Issued: 02/01/1994
• Est. Priority Date: 10/11/1990
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Hikita, Toshiya, Sakano, Yukio, Fujisawa, Tetsuo
• Primary Examiner(s): BRINICH, STEPHEN M
• Application Number:
  US07/773,728
• Time in Patent Office: 846 Days
• Field of Search: 358/429-430, 358/426, 358/261.1-261.3, 358/262.1, 358/456-458, 358/461
• US Class Current: 382/251
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: H04N 1/40075 Descreening, i.e. converting a halftone signal into a corresponding continuous-tone signal; Rescreening, i.e. combined descreening and halftoning
• 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 recorder for converting input bilevel image data to multilevel data, executing various kinds of image processing with the mutlilevel data, and then recording the processed multilevel data. The image recorder converts input bilevel image data to M-level data (M being equal to or greater than 2), then requantized to N-level data, and then fed to a printer capable of recording data in three or more levels. The bilevel-to-multilevel conversion is effected in matching relation to the pattern of the input bilevel data. A plurality of bilevel-to-multilevel conversion means of different kinds are provided. The bilevel-to-multilevel conversion system is changed on the basis of the kind of input bilevel data. The M-level data is subjected to edge enhancement, magnification change, and gamma correction. Color image data produced by color separation are processed color by color and then fed to a printer.

Claims

1. An image recorder comprising:

bilevel-to-multilevel converting means for converting input bilevel image data to M-level data (M being equal to or greater than

     3), said bilevel-to-multilevel converting means comprising a filter having weighting coefficients;

requantizing means for converting multilevel data to N-level data (N being equal to or greater than 2 and smaller than M); and

recording means capable of recordig a single pixel in any one of N levels;

input image data being converted to M-level data by said bilevel-to-multilevel converting means, then converted to N-level data by said requantizing means, and then recorded by said recording means.

2. An image recorder comprising:

bilevel-to-multilevel converting means for converting input blevel image data to M-level data (M being equal to or greater than

     3), said bilevel-to-multilevel converting means comprising a filter having weighting coefficients and executing bilevel-to-multilevel conversion on the basis of a pattern of input binary image data;

requantizing means for converting multilevel data to N-level data (N being equal to or greater than 2 and smaller than M); and

recording means capable of recording a single pixel in any one of N levels;

input bilevel image data being converted to M-level data, then subjected to image processing, then converted to N-level data by said requantizing means, and then recorded said recording means.

3. An image recoder comprising:

a plurality of bilevel-to-multilevel converting means each being operable by a particular system for converting input bilevel image data to M-level data (M being equal to or greater than

     3), said bilevel-to-multilevel converting means each comprising a filter having weighting coefficients;

requantizing means for converting multilevel data to N-level data (N being equal to or greater than 2 and smaller than M); and

recording means capable of recording a single pixel in any one of N levels;

input bilevel image data being converted to M-level data by said bilevel-to-multilevel converting means, then subjected to image processing, requantized by said requantizing means to N-level data, and then recorded by said recording means.

4. An image recorder comprising:

bilevel-to-multilevel converting means for converting input bilevel image data M-level data (M being equal to or greater than

     3), said bilevel-to-multilevel converting means comprising a filter and a plurality of bilevel-to-multilevel conversion patterns;

requantizing means for converting multilevel data to N-level data (N being equal to or greater than 2 and smaller than M); and

recording means capable of recording a single pixel in any one of N levels;

input bilevel image data being converted to M-level data by said bilevel-to-multilevel converting means, then subjected to image processing, then converted to N-level data, and then recorded by said recording means.

5. An image recorder comprising:

bilevel-to-multilevel converting means including a filter having weighting coefficients for converting input bilevel image data to M-level data (M being equal to or greater than

     3);

requantizing means for converting multilevel data to N-level data (N being equal to or greater than 2 and smaller than M); and

recording means capable of recording a single pixel in any one of N levels;

input bilevel image data being converted to M-level data, then subjected to image processing, then converted to N-level data by said requantizing means, and then recorded by said recording means;

said recorder changing a bilevel-to-multilevel conversion system depending on the kind of input bilevel image data.

6. An image recorder comprising:

bilevel-to-multilevel converting means for converting input bilevel data to M-level data (M being equal to or greater than

     3), said bilevel-to-multilevel converting means comprising a filter having weighting coefficients;

requantizing means for converting multilevel data to N-level data (N being equal to or greater than 2 and smaller than M);

recording means capable of recording a single pixel in any one of N levels; and

image processing means for executing at least one of edge enhancement, magnification change and gamma correction with said M-level data;

input bilevel image being converted to M-level data by said bilevel-to-multilevel converting means, then subjected to at least one of edge enhancement, magnification change and gamma correction, then converted to N-level data by said requantizing means, an then recorded by said recording means.

7. An image recorder comprising:

a plurality of bilevel-to-multilevel converting means each being assigned to respective one of a plurality of separated colors for converting bilevel image data of associated color to M-level data of said color (M being equal to or greater than

     3);

a plurality of requantizing means each being associated with said plurality of bilevel-to-multilevel converting means for converting said M-level data of particular color to N-level data (N being equal to or greater than 2 and smaller than M); and

a printer capable of recording data in N levels per pixel in each color;

bilevel image data of said plurality of colors each being converted to M-level data by a filter incorporated in associated one of said bilevel-to-multilevel converting means and having weighting coefficients, then converted to N-level data by associated one of said requantizing means, and then recorded by said printer.

8. An image recorder comprising:

a plurality of bilevel-to-multilevel converting means each being assigned to respective one of a plurality of separated colors for converting bilevel image data of associated color to M-level data (M being equal to or greater than

     3);

a plurality of gamma correcting means each being associated with respective one of said plurality of bilevel-to-multilevel converting means for executing gamma correction with said M-level data;

a plurality of quantizing means each being associated with said plurality of gamma correcting means for converting the gamma-corrected data of associated color to N-level data (N being equal to or greater than 2 and smaller than M); and

a printer capable of recording data in N levels per pixel in each color;

bilevel image data of said plurality of colors each being converted to M-level data by a filter incorporated in associated one of said bilevel-to-multilevel converting means and having weighting coefficients, then subjected to gamma correction color by color, then converted to N-level data by associated one of said requantizing means, and then recorded by said printer.

9. An image recorder comprising:

a plurality of bilevel-to-multilevel converting means each being assigned to respective one of a plurality of separated colors for converting bilevel image data of associated color to M-level data (M being equal to or greater than

     3);

a plurality of gamma correcting means each being associated with respective one of said plurality of bilevel-to-multilevel converting means for executing gamma correction with said M-level data;

means for selecting gamma correction;

a plurality of quantizing means each being associated with said plurality of gamma correcting means for converting the gamma-corrected data of associated color to N-level data (N being equal to or greater than 2 and smaller than M); and

a printer capable of recording data in N levels per pixel in each color;

bilevel image data of said plurality of colors each being converted to M-level data by a filter incorporated in associated one of said bilevel-to-multilevel converting means and having weighting coefficients, then subjected to gamma correction selected color by color, then converted to N-level data by associated one of said requantizing means, and then recorded by said printer.