Camera system and camera control method

• US 20040179132A1
• Filed: 01/16/2004
• Published: 09/16/2004
• Est. Priority Date: 03/14/2003
• Status: Abandoned Application

• Current Assignee: Yokogawa Electric Corporation
• Original Assignee: Yokogawa Electric Corporation
• Inventors: Takahashi, Takahiro, Fujino, Kenji, Katsurai, Toru
• Application Number:
  US10/758,353
• Publication Number:
  US 20040179132A1
• Time in Patent Office: Days
• US Class Current: 348/363
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
• CPC Class Codes: H04N 23/75 by influencing optical camera components
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors

Abstract

The present invention is intended for realizing a camera system and camera control method whereby wide dynamic-range optimum images can be obtained.

The present invention is characterized by improvements made to a camera system for obtaining optimum images by controlling a compression curve for the dynamic range of an image sensor according to the brightness of a subject. The camera system comprises an iris for adjusting the amount of light introduced to the image sensor; an iris driver for driving the iris; an iris controller for determining an iris value according to the image data of the image sensor in order to let the iris driver make an iris value correction accordingly; and a dynamic range adjuster for correcting the compression curve according to the image data of the image sensor.

Claims

1. A camera system for obtaining optimum images by controlling a compression curve for the dynamic range of an image sensor according to the brightness of a subject, comprising:

an iris for adjusting the amount of light introduced to said image sensor;

an iris driver for driving said iris;

an iris controller for determining an iris value according to the image data of said image sensor in order to let said iris driver make an iris value correction accordingly; and

a dynamic range adjuster for correcting said compression curve according to the image data of said image sensor.

2. The camera system of claim 1, wherein said iris controller comprises:

an average luminance calculator for determining the average luminance of said image data; and

an iris calculator for calculating an iris value at which the average luminance of said average luminance is adjusted to a desired average luminance, in order to let said iris driver make an iris value correction accordingly.

3. The camera system of claim 1, wherein said iris controller comprises:

a histogram calculator for determining the luminance histogram of said image data;

a distribution position detector for detecting the distribution of a dark area according to the luminance histogram of said histogram calculator; and

an iris calculator for calculating an iris value, according to said distribution detected by said distribution position detector, at which the distribution of said dark area is shifted to a desired position, in order to let said iris driver make an iris value correction accordingly.

4. The camera system of claim 1, 2 or 3, wherein said image sensor is a CMOS sensor.

5. A camera control method for obtaining optimum images by controlling a compression curve for the dynamic range of an image sensor according to the brightness of a subject, comprising the steps of:

iris control for determining an iris value according to the image data of said image sensor, in order to let an iris driver control an iris for adjusting the amount of light introduced to said image sensor; and

dynamic range adjustment for correcting a compression curve according to the image data of said image sensor.

6. The camera control method of claim 5, wherein said iris control step includes the steps of:

average luminance calculation for determining the average luminance of said image data; and

iris calculation for calculating an iris value at which said average luminance is adjusted to a desired average luminance, in order to let said iris driver make an iris value correction accordingly.

7. The camera control method of claim 5, wherein said iris control step includes the steps of:

histogram calculation for determining the luminance histogram of said image data;

distribution detection for detecting the distribution of a dark area according to said luminance histogram; and

iris calculation for calculating an iris value, according to said distribution, at which said dark-area distribution is shifted to a desired position, in order to let said iris driver make an iris value correction accordingly.

8. The camera control method of claim 5, 6 or 7, wherein said image sensor is a CMOS sensor.