Half tone image processing apparatus

• US 5,406,390 A
• Filed: 06/21/1994
• Issued: 04/11/1995
• Est. Priority Date: 09/18/1990
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Mizoguchi, Yoshito
• Primary Examiner(s): Chilcot, Jr., Richard E.
• Assistant Examiner(s): BACARES, RAFAEL D
• Application Number:
  US08/263,409
• Time in Patent Office: 294 Days
• Field of Search: 358/75, 358/80, 358/406, 358/455, 358/456
• US Class Current: 358/3.24
• CPC Class Codes: H04N 1/4078 using gradational references, e.g. grey-scale test pattern analysis

Abstract

An image processing apparatus for processing a half tone image comprises: an input device to input an image signal; an image forming circuit to form an image onto a recording medium such as a photosensitive drum on the basis of the image signal supplied by the input device; a generator to generate a plurality of image data having different densities; a density detector to detect a density of the image formed on the recording medium by the image forming circuit on the basis of the image data generated from the generator; and a forming circuit to form a plurality of density conversion coefficients to convert the density of the image signal supplied by the input device on the basis of the densities of the plurality of images which are detected by the density detector.

Claims

1. An image processing apparatus comprising:

input means for inputting a color image signal;

image forming means for forming color images by applying developing agents of a plurality of colors onto a reusable recording medium on the basis of the color image signal supplied from the input means;

transfer means for transferring the color image formed on the recording medium to a recording sheet;

generating means for generating a plurality of image data having different densities;

density detecting means for detecting densities of the color image formed on the recording medium by said image forming means; and

control means for controlling said generating means and said image forming means and said density detecting means so as to cause said generating means and said image forming means and said density detecting means to form images of a plurality of different densities of a predetermined color and to detect densities of each formed image,

wherein said control means produces a plurality of conversion coefficients for correcting input-output characteristics of densities of the image signal supplied to said input means, on the basis of the densities of each image detected by said density detecting means, and causes a memory to store the produced conversion coefficients, and

wherein said control means produces the conversion coefficients for each of said plurality of colors.

2. An apparatus according to claim 1, wherein said generating means sequentially generates a plurality of image data having different densities.

5. An apparatus according to claim 1, wherein said recording medium is a drum-shaped photosensitive medium.

6. An apparatus according to claim 1, wherein said image forming means comprises latent image forming means for forming a latent image on said recording medium and a plurality of developing means including the developing agents for each different color, for developing the latent image.

3. An image processing method in an image forming apparatus having input means for inputting a color image signal and image forming means for forming color images by applying developing agents of a plurality of colors onto a reusable recording medium on the basis of the color image signal supplied by said input means, and transfer means for transferring the color image formed on the recording medium to a recording sheet, comprising the steps of:

a) forming images of a plurality of different densities of a predetermined color on the recording medium by the image forming means on the basis of a plurality of image data having different predetermined densities;

b) detecting densities of the plurality of images formed on the recording medium in said forming step, respectively;

c) producing a plurality of conversion coefficients for correcting input-output characteristics of densities of the image signal supplied to said input means, on the basis of densities of each image detected in said detection step;

d) storing the plurality of conversion coefficients produced in said producing step into a memory; and

e) repeating said forming, detecting, producing and storing steps for each of said plurality of colors.

7. An apparatus according to claim 3, wherein said recording medium is a drum-shaped photosensitive medium.

8. An apparatus according to claim 3, wherein said image forming means comprises latent image forming means for forming a latent image on said recording medium and a plurality of developing means including the developing agents for each different color, for developing the latent image.

4. A color image forming apparatus comprising:

input means for inputting a color image signal;

image forming means for forming a color image on the basis of the color image signal which is supplied by said input means, said image forming means having a plurality of developing means respectively containing agents of yellow, magenta, cyan and black;

generating means for generating a plurality of image data having different densities;

density detecting means for detecting a density of images formed by said image forming means; and

control means for controlling said generating means and said image forming means and said density detecting means so as to cause said generating means and said image forming means and said density detecting means to form images of a plurality of different densities as to each of yellow, magenta, cyan and black on a single recording medium and to detect densities of the images of each color formed on said single recording medium,

wherein said control means produces a plurality of conversion coefficients for correcting input-output characteristics of densities of the image signal supplied to said input means, on the basis of densities of a plurality of images for each of yellow, magenta, cyan and black detected by said density detecting means.

9. An apparatus according to claim 4, wherein said recording medium is used repeatedly to form the plurality of images.

10. An apparatus according to claim 9, wherein said recording medium is a drum-shaped photosensitive medium.