Brightness adjusting apparatus for stereoscopic camera

• US 6,987,534 B1
• Filed: 08/29/2000
• Issued: 01/17/2006
• Est. Priority Date: 08/30/1999
• Status: Active Grant

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Seta, Itaru
• Primary Examiner(s): MOE, AUNG SOE
• Application Number:
  US09/650,705
• Time in Patent Office: 1,967 Days
• Field of Search: 348/229.1, 348/255, 348/67.B, 348/221.1, 348/42, 348/47, 348/43, 353/7, 352/57, 376/322, 376/324, 376/325
• US Class Current: 348/229.1
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves
• CPC Class Codes: H04N 13/111 Transformation of image signals corresponding to virtual viewpoints, e.g. spatial image interpolation
• CPC Class Codes: H04N 13/133 Equalising the characteristics of different image components, e.g. their average brightness or colour balance
• CPC Class Codes: H04N 13/189 Recording image signals; Reproducing recorded image signals
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 13/246 Calibration of cameras
• CPC Class Codes: H04N 13/25 using two or more image sensors with different characteristics other than in their location or field of view, e.g. having different resolutions or colour pickup characteristics; using image signals from one sensor to control the characteristics of another sensor
• CPC Class Codes: H04N 13/296 Synchronisation thereof; Control thereof
• CPC Class Codes: H04N 2013/0081 Depth or disparity estimation from stereoscopic image signals
• CPC Class Codes: H04N 2013/0096 Synchronisation or controlling aspects
• CPC Class Codes: H04N 23/76 by influencing the image signals

Abstract

An apparatus for adjusting a brightness balance of a stereoscopic camera includes a gain control amplifier and a micro-computer. The gain control amplifier adjusts a brightness balance of a pair of images outputted from the stereoscopic camera by gain. The micro-computer calculates a first evaluation value representing a magnitude of an entire brightness of a first evaluation window established in a reference image outputted from the gain control amplifier and calculates a second evaluation value representing a magnitude of an entire brightness of a second evaluation window established in a comparison image outputted from an adjusting device, and established in an area having a brightness correlation with the first evaluation window. Also, the micro-computer corrects a gain so as to reduce the difference between the first evaluation value and the second evaluation value.

Claims

1. A brightness adjusting apparatus for adjusting a brightness balance of a pair of images outputted from a stereoscopic camera having a first camera imaging a reference image and a second camera imaging a comparison image, comprising:

an adjusting means for adjusting said brightness balance by varying a gain;

a distance data calculating means for finding a pixel block having a brightness correlation with a pixel block of said reference image in said comparison image and for calculating a distance data based on a city block distance between both pixel blocks;

a distance data assigning means for assigning said distance data to said pixel block of said reference image;

a first evaluation window establishing means for establishing a first evaluation window composed of a plurality of pixel blocks in said reference image;

a parallax calculating means for calculating a parallax based on said distance data;

a second evaluation window establishing means for establishing a second evaluation window composed of a plurality of pixel blocks in said comparison image based on said parallax;

a first evaluation value calculating means for calculating a first evaluation value representing a magnitude of an entire brightness of said first evaluation window;

a second evaluation value calculating means for calculating a second evaluation value representing a magnitude of an entire brightness of said second evaluation window; and

a correcting means for correcting said gain so as to reduce the difference between said first evaluation value and said second evaluation value.

2. The apparatus according to claim 1, wherein

said second evaluation window is established in a horizontally offset position from said first evaluation window.

3. The apparatus according to claim 1, wherein

said parallax is calculated based on a histogram of said distance data.

4. The apparatus according to claim 1, wherein

said parallax is calculated based on a mean value of said distance data.

5. The apparatus according to claim 1, wherein

said second evaluation window is established in a horizontally offset position by an amount of said parallax from said first evaluation window.

6. The apparatus according to claim 1, further comprising:

a correlation coefficient calculating means for calculating a correlation coefficient based on said first evaluation value and said second evaluation value.

7. The apparatus according to claim 6, wherein

said first evaluation value and said second evaluation value are verified by said correlation coefficient.

8. The apparatus according to claim 1, wherein

said second evaluation window is established by finding a pixel block having a largest brightness correlation with a pixel block of said first evaluation window in said comparison image within a specified range on the basis of a reference point established based on said parallax.

9. The apparatus according to claim 1, wherein

said parallax is calculated only based on said distance data of a pixel block having a larger variation of brightness than a threshold value.

10. The apparatus according to claim 1, wherein

said first evaluation value and said second evaluation value are calculated from at least one pair of first and second zones prepared in said reference image and said comparison image, respectively and said pair of zones are established being horizontally offset by an amount of pixels according to the position of said zones.

11. The apparatus according to claim 10, wherein

said amount of pixels are established in consideration of a tendency of a distance to an solid object projected in said first zones.

12. A brightness adjusting apparatus for adjusting a brightness balance of a pair of images outputted from a stereoscopic camera having a first camera imaging a reference image and a second camera imaging a comparison image, comprising:

an adjusting means for adjusting said brightness balance by varying a gain;

a first evaluation window establishing means for establishing a first evaluation window composed of a plurality of pixel blocks of said reference image;

a second evaluation window establishing means for establishing a second evaluation window composed of a plurality of pixel blocks of said comparison image;

a first evaluation value calculating means for calculating first evaluation value representing a brightness magnitude of said first evaluation window established in said reference image;

a second evaluation value calculating means for calculating a second evaluation value representing a brightness magnitude of said second evaluation window established in said comparison image; and

a correcting means for correcting said gain so as to reduce the difference between said first evaluation value and said second evaluation value,

wherein said second evaluation window is established with offset amount in the direction of the stereo matching against a position of said first evaluation window, said offset amount being established taking a tendency with respect to a distance to object which is projected in said first evaluation window.

13. A brightness adjusting apparatus for adjusting a brightness balance of a pair of images outputted from a stereoscopic camera having a first camera imaging a reference image and a second camera imaging a comparison image, comprising;

an adjusting means for adjusting said brightness balance by varying a gain;

a first evaluation window establishing means for establishing a first evaluation window composed of a plurality of pixel blocks of said reference image;

a second evaluation window establishing means for establishing a second evaluation window composed of a plurality of pixel blocks of said comparison image;

a first evaluation value calculating means for calculating a first evaluation value representing a brightness magnitude of said first evaluation window established in said reference image;

a second evaluation value calculating means for calculating a second evaluation value representing a brightness magnitude of said second evaluation window established in said comparison image; and

a correcting means for correcting said gain so as to reduce the difference between said first evaluation value and said second evaluation value,

wherein said first evaluation window is composed of plurality of first zones prepared in said reference image each of said first zones is established at difference part of said reference image,

said second evaluation window is composed of plurality of second zones prepared in said reference image,

said second zones being established to correspond to respective first zones,

each of said second zones being established with an offset amount with respect to a corresponding first zone, in the direction of stereo matching, said offset amount being potentially different for each of said second zones.

14. A brightness adjusting apparatus according to claim 13, wherein said difference part of said reference image includes an upper part, a middle part, and a lower part of said reference image.