Electronic endoscope system with color-balance alteration process

• US 6,967,673 B2
• Filed: 06/25/2002
• Issued: 11/22/2005
• Est. Priority Date: 06/26/2001
• Status: Expired due to Fees

• Current Assignee: Pentax Corporation (Hoya Corporation)
• Original Assignee: Pentax Corporation (Hoya Corporation)
• Inventors: Kimishima, Mikihito, Ozawa, Ryo
• Primary Examiner(s): LEE, RICHARD J
• Application Number:
  US10/178,758
• Publication Number:
  US 20030030722A1
• Time in Patent Office: 1,246 Days
• Field of Search: H04/N00.7/18, 348/45, 348 65- 72, 600/101, 600/109, 600/113, 600/168, 606/14
• US Class Current: 348/71
• CPC Class Codes: A61B 1/00009 of image signals during a use of endoscope
• CPC Class Codes: A61B 1/0638 providing two or more wavelengths
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control

Abstract

An electronic endoscope system includes a video scope having a solid-state image sensor for successively producing a frame of color image-pixel signals, and an image-signal processor for producing a color video signal based on the frame of color image-pixel signals. A calculation system calculates a difference value between a value of a central single-color image-pixel signal and an average of values of one selected from single-color image-pixel signals surrounding the central single-color image-pixel signal. A color-balance alteration system alters the value of the central single-color image-pixel signal based on the difference value calculated by the calculation system. A selection system performs the selection of the circumferential image-pixel signals such that the circumferential image-pixel signals to be selected are farther from the central image-pixel signal, as a spatial frequency of an endoscope image to be reproduced based on the color video signals is lower.

Claims

1. An electronic endoscope system including a video scope having a solid-state image sensor that successively produces a frame of color image-pixel signals, and an image-signal processor that produces a color video signal based on said frame of color image-pixel signals, said electronic endoscope system comprising:

a calculator that calculates a difference value between a value of a central single-color image-pixel signal and an average of values of some circumferential single-color image- pixel signals selected from single-color image-pixel signals surrounding said central single-color image-pixel signal;

a color-balance alteration system that alters the value of said central single-color image-pixel signal based on the difference value calculated by said calculator; and

a selector that selects said circumferential single-color image-pixel signals such that the distance between the circumferential single-color image-pixel signals to be selected and said central single-color image-pixel signal increases as a spatial frequency of an endoscope image to be reproduced based on said color video signal decreases.

2. An electronic endoscope system as set forth in claim 1, wherein said calculator further includes a multiplier that multiplies said difference value by a density factor, and the alteration of the value of said central single-color image-pixel signal by said color-balance alteration system is performed based on the multiplied difference value.

3. An electronic endoscope system as set forth in claim 1, wherein the color-balance alteration system further includes:

a determiner that determines whether the value of said central single-color image-pixel signal is lower than said average of values; and

a subtractor that subtracts the absolute value of the difference value from the value of said central single-color image-pixel signal when it is determined by said determiner that the value of said central single-color image-pixel signal is lower than said average of values, with the value of said central single-color image-pixel signal being unchanged when it is determined by said determiner that the value of said central single-color image-pixel signal is equal to or higher than said average of values.

4. An electronic endoscope system as set forth in claim 3, wherein the color-balance alteration system further includes a multiplier that multiplies the difference value by a factor, and the absolute value of the multiplied difference value is subtracted from the value of said central single-color image-pixel signal by said subtractor.

5. An electronic endoscope system as set forth in claim 1, wherein said selector is associated with an electronic zooming system introduced in said image-signal processor.

6. An electronic endoscope system as set forth in claim 5, wherein said selector is further associated with at least two video scopes featuring different types of solid-state image sensors, which produce different numbers of image-pixel signals in one frame.

7. An electronic endoscope system as set forth in claim 1, wherein said selector is associated with an optical zooming system introduced in said video scope.

8. An electronic endoscope system as set forth in claim 7, wherein said selector is further associated with at least two video scopes featuring different types of solid-state image sensors, which produce different numbers of image-pixel signals in one frame.

9. An electronic endoscope system as set forth in claim 1, further comprising a diaphragm system that maintains a constant overall luminance of the reproduced endoscope image, wherein said selector is associated with said diaphragm system.

10. An electronic endoscope system as set forth in claim 9, wherein said selector is further associated with at least two video scopes featuring different types of solid-state image sensors, which produce different numbers of image-pixel signals in one frame.

11. An electronic endoscope system as set forth in claim 5, wherein said spatial frequency varies due to a change of an enlarging rate of said electronic zooming system.

12. An electronic endoscope system as set forth in claim 7, wherein said spatial frequency varies due to a change of a magnifying power of said optical zooming system.

13. An electronic endoscope system as set forth in claim 9, wherein said spatial frequency varies due to a change of an opening value of said diaphragm system.

14. An electronic endoscope system as set forth in claim 1, wherein said selector is associated with at least two video scopes featuring different types of solid-state image sensors, which produce different numbers of image-pixel signals in one frame.

15. An electronic endoscope system as set forth in claim 14, wherein said spatial frequency varies due to a substitution of a different type of said video scope.