Image processing apparatus

• US 5,245,445 A
• Filed: 03/18/1992
• Issued: 09/14/1993
• Est. Priority Date: 03/22/1991
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Fujisawa, Tetsuo
• Primary Examiner(s): Coles, Sr., Edward L.
• Assistant Examiner(s): LEE, CHEUKFAN
• Application Number:
  US07/853,431
• Time in Patent Office: 545 Days
• Field of Search: 358/458, 358/462, 358/465, 358/466, 358/467, 358/447, 358/444, 358/448, 382/54, 382/22
• US Class Current: 358/3.15
• CPC Class Codes: G06T 2207/10008 from scanner, fax or copier
• CPC Class Codes: G06T 2207/30176 Document
• 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 1/4092 Edge or detail enhancement
• CPC Class Codes: H04N 19/80 Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation H04N19/635, H04N19/86 take precedence
• CPC Class Codes: Y10S 706/90 Fuzzy logic

Abstract

An image processing apparatus includes an image processing part for carrying out an image processing for an input image having pixels with multilevel bits supplied by an input unit, the image processing being carried out at a processing level among a plurality of predetermined processing levels, a first detecting part for detecting an edge quantity of the input image, a second detecting part for detecting a screened dot quantity of the input image, and a control part for determining a control index proportional to the detected edge quantity and the detected screened dot quantity, and for supplying the determined control index to the image processing part, so that the image processing part selects a processing level appropriate for the input image from the processing levels in response to the control index, and carries out an image processing for the input image at the selected processing level.

Claims

1. An image processing apparatus comprising:

image processing means for carrying out an image processing for an input image having pixels with multilevel bits supplied by an input unit, said image processing being carried out at a processing level from among a plurality of predetermined processing levels;

first detecting means for detecting an edge quantity of the input image supplied by the input unit;

second detecting means for detecting a screened dot quantity of the input image supplied by the input unit; and

control means, coupled to the first and second detecting means, for determining a control index proportional to the detected edge quantity and the detected screened dot quantity, and for supplying the determined control index to said image processing means, so that said image processing means selects a processing level appropriate for the input image from said predetermined processing levels in response to the control index supplied by said control means, and carries out an image processing for the input image at the selected processing level.

2. An apparatus according to claim 1, wherein said control means determines said control index based on a predetermined characteristic relationship between the edge quantity and the processing level, based on a predetermined characteristic relationship between the screened dot quantity and the processing level, and based on a predetermined characteristic relationship between the control index and the processing level.

3. An apparatus according to claim 1, wherein said control means determines said control index based on a first membership function defining a predetermined characteristic relationship between the edge quantity and the processing level, based on a second membership function defining a predetermined characteristic relationship between the screened dot quantity and the processing level, and based on a third membership function defining a predetermined characteristic relationship between the control index and the processing level, whereby said control index is determined by detecting a center of gravity of an area in a diagram described by said third membership function whose processing level is appropriate for both the detected edge quantity and the detected screened dot quantity.

4. An apparatus according to claim 1, wherein said image processing means carries out a filtering process for the input image at a filtering level from among a plurality of predetermined filtering levels by selecting a filtering level appropriate for the input image from said predetermined filtering levels in response to the control index supplied by said control means.

5. An apparatus according to claim 4, wherein said control means determines said control index based on a predetermined characteristic relationship between the edge quantity and the filtering level, based on a predetermined characteristic relationship between the screened dot quantity and the filtering level, and based on a predetermined characteristic relationship between the control index and the filtering level.

6. An apparatus according to claim 4, wherein said control means determines said control index based on a first membership function defining a predetermined characteristic relationship between the edge quantity and the filtering level, based on a second membership function defining a predetermined characteristic relationship between the screened dot quantity and the filtering level, and based on a third membership function defining a predetermined characteristic relationship between the control index and the filtering level, whereby said control index is determined by detecting a center of gravity of an area in a diagram described by said third membership function whose filtering level is satisfied by both the detected edge quantity and the detected screened dot quantity.

7. An apparatus according to claim 4, wherein said image processing means carries out said filtering process, which process is divided into two kinds of operations, center pixel filtering operations performed with respect to a center pixel of a filter matrix and neighboring pixel filtering operations performed with respect to neighboring pixels surrounding the center pixel of the filter matrix.

8. An apparatus according to claim 4, wherein said image processing means includes smoothing process modules for carrying out center pixel filtering operations and for carrying out neighboring pixel filtering operations, which two kinds of operations are controlled independently of each other in response to the control index supplied by said control means, and said image processing means includes edge intensifying process modules for carrying out center pixel filtering operations and for carrying out neighboring pixel filtering operations, which two kinds of operations are also controlled independently of each other in response to the control index supplied by said control means.