Noise reducing apparatus

• US 6,781,625 B2
• Filed: 03/14/2003
• Issued: 08/24/2004
• Est. Priority Date: 03/15/2002
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Hayashi, Kenkichi
• Primary Examiner(s): Christensen, Andrew
• Assistant Examiner(s): GENCO, BRIAN C
• Application Number:
  US10/387,481
• Publication Number:
  US 20030174223A1
• Time in Patent Office: 529 Days
• Field of Search: 348/241, 348/533, 348/571, 348/606, 348/607, 348/609, 348/618, 348/627, 348/252, 378/98.12, 382/268, 382/296, 382/270, 382/260, 382/261, 382/262, 382/266, 386/113, 386/116, 386/114, 386/76
• US Class Current: 348/252
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/75 Unsharp masking
• CPC Class Codes: H04N 25/60 Noise processing, e.g. detecting, correcting, reducing or removing noise
• CPC Class Codes: H04N 5/21 Circuitry for suppressing or minimising disturbance, e.g. moiré or halo

Abstract

First and second noise detecting circuits detect whether image data output from a signal processing circuit includes noise. If the image data includes noise, first and second noise reducing circuits reduce the noise. An edge extracting circuit extracts edge data from the first image data in which noise has been reduced. An adding circuit adds the edge data and second image data, which has been output by the second noise reducing circuit, and outputs the resultant data. Even though edge enhancement is applied, noise is not enhanced but noise is reduced.

Claims

1. A noise reducing apparatus, comprising:

a first noise detecting circuit, to which a noise-reduction-target image signal representing an image to undergo noise reduction is input, for detecting whether the noise-reduction-target image signal includes a noise component to be reduced on the basis of a first threshold value;

a first noise reducing circuit for reducing the noise component and outputting a resultant first image signal when said first noise detecting circuit detects the noise component to be reduced in the noise-reduction-target image signal;

an edge extracting circuit for extracting an edge signal from the first image signal output from said first noise reducing circuit;

a second noise detecting circuit, to which the noise-reduction-target image signal is input, for detecting whether the noise-reduction-target image signal includes a noise component to be reduced on the basis of a second threshold value, the first threshold value in the first noise detecting circuit and the second threshold value in the second noise detecting circuit being set independently from each other;

a second noise reducing circuit for reducing the noise component and outputting a resultant second image signal when said second noise detecting circuit detects the noise component to be reduced in the noise-reduction-target image signal; and

an adding circuit for adding the edge signal, which has been extracted by said edge extracting circuit, and the second image signal, which has been output by said second noise reducing circuit and outputting the result.

2. The apparatus according to claim 1, wherein said first noise reducing circuit is such that extent to which the noise component is reduced can be adjusted.

3. The apparatus according to claim 1, wherein said second noise reducing circuit is such that extent to which the noise component is reduced can be adjusted.

4. The apparatus according to claim 1, wherein said first and second noise detecting circuits are physically one device.

5. The apparatus according to claim 1, wherein said first and second noise reducing circuits are physically one device.

6. A noise reducing method, comprising:

detecting whether a noise-reduction-target image signal representing an image includes a noise component to be reduced based on a first threshold value;

reducing the noise component and outputting a resultant first image signal when said detecting step detects the noise component based on the first threshold value;

extracting an edge signal from the first image signal;

detecting whether the noise-reduction-target image signal includes a noise component to be reduced based on a second threshold value, wherein the first threshold value and the second threshold value are set independently from each other;

reducing the noise component and outputting a resultant second image signal when said detecting step detects the noise component based on the second threshold value; and

adding the edge signal and the second image signal and outputting the result.

7. The method according to claim 6, further comprising adjusting an extent to which the noise component is reduced for the first image signal.

8. The method according to claim 6, further comprising adjusting an extent to which the noise component is reduced for the second image signal.