IMAGE PROCESSING APPARATUS AND ITS ADJUSTMENT METHOD

• US 20120206600A1
• Filed: 02/14/2012
• Published: 08/16/2012
• Est. Priority Date: 02/15/2011
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Sato, Hironori, Osanai, Satoshi
• Granted Patent: US 9,992,468 B2
• Time in Patent Office: Days
• US Class Current: 348/148
• CPC Class Codes: G06V 10/56 relating to colour
• CPC Class Codes: H04N 1/6027 Correction or control of colour gradation or colour contrast H04N1/6058 takes precedence
• CPC Class Codes: H04N 1/6047 wherein the test pattern is part of an arbitrary user image
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86

Abstract

In an image processing apparatus, an image acquisition unit acquires an image. A correction unit corrects pixel values of pixels composed of the acquired image by using correction coefficients to produce a correct image. An object recognition unit recognizes an object in the corrected image. A storage unit stores in advance standard color characteristics of a predetermined object which is a recognition target. A color characteristics acquisition unit acquires color characteristics of the predetermined object if the predetermined object is recognized by the object recognition unit. A comparison unit compares the color characteristics of the acquired object with the standard color characteristics of the same predetermined object stored in advance in the storage unit. An updating unit updates the correction coefficients used in the correction unit based on a result of comparison so as to reduce a difference between the color characteristics and the standard color characteristics.

Claims

1. An image processing apparatus, comprising:

an image acquisition unit that acquires an image;

a correction unit that corrects pixel values of the image acquired by the image acquisition unit by using correction coefficients to produce a corrected image;

an object recognition unit that recognizes an object in the corrected image;

a storage unit that stores in advance standard color characteristics of a predetermined object which is a recognition target;

a color characteristics acquisition unit that if the predetermined object is recognized by the object recognition unit, acquires color characteristics of the predetermined object;

a comparison unit that compares the color characteristics of the predetermined object acquired by the color characteristics acquisition unit with the standard color characteristics of the same predetermined object stored in advance by the storage unit; and

an updating unit that updates the correction coefficients used by the correction unit based on a result of comparison of the color characteristics and the standard color characteristics so as to reduce a difference between the color characteristics and the standard color characteristics.

2. The image processing apparatus according to claim 1, wherein

the comparison unit compares the color characteristics with the standard color characteristics in a predetermined color space.

3. The image processing apparatus according to claim 2, wherein

the updating unit acquires an extent of deviation of the color characteristics from the standard color characteristics in the color space, and updates the correction coefficients based on the extent of deviation in the color space.

4. The image processing apparatus according to claim 2, wherein

the updating unit gradually varies values of the correction coefficients, acquires the color characteristics of the predetermined object using the varied correction coefficients, compares the color characteristics with the standard color characteristics in the color space, calculates a difference between the color characteristics and the standard color characteristics in the color space, and sets the correction coefficients that minimizes the difference as updated correction coefficients.

5. The image processing apparatus according to claim 1, wherein:

the image acquisition unit is a camera mounted on a vehicle;

the correction unit, the object recognition unit, the storage unit, the color characteristics acquisition unit, the comparison unit, and the updating unit are included in at least one processor mounted on vehicle; and

the processor includes a control unit that controls a state of an on-board device mounted on the vehicle based on the object recognized by the object recognition unit.

6. A method for adjusting an image processing apparatus that includes an image acquisition unit which acquires an image, a correction unit that corrects pixel values of pixels composed of an acquired image by using correction coefficients, and an object recognition unit that recognizes an object in a corrected image whose pixel values are corrected, the method comprising:

storing standard color characteristics of an image of a predetermined standard light source in the storage unit in advance;

acquiring, at the image acquisition unit, an image of the predetermined standard light source;

correcting, at the correction unit, the acquired image;

comparing, at a comparison unit, color characteristics of the corrected image with the standard color characteristics of the image stored in advance in the storage unit; and

updating, at a updating unit, the correction coefficients based on a result of comparison of the color characteristics and the standard color characteristics so as to reduce a difference between the color characteristics and the standard color characteristics.

7. The method according to claim 6, wherein

in the comparing at the comparison unit, the color characteristics are compared with the standard color characteristics in a predetermined color space.

8. The method according to claim 7, wherein

in the updating at the updating unit, an extent of deviation of the color characteristics from the standard color characteristics in the color space is acquired, and the correction coefficients are updated based on the extent of deviation in the color space.

9. The method according to claim 7, wherein

in the updating at the updating unit, values of the correction coefficients are gradually varied, the color characteristics of the predetermined object are acquired using the varied correction coefficients, the color characteristics are compared with the standard color characteristics in the color space, a difference between the color characteristics and the standard color characteristics in the color space is calculated, and the correction coefficients that minimize the difference are set as updated correction coefficients.

10. The method according to claim 6, wherein:

the image acquisition unit is a camera mounted on a vehicle;

the correction unit, the object recognition unit, the storage unit, the color characteristics acquisition unit, the comparison unit, and the updating unit are included in at least one processor mounted on vehicle; and

an on-board device that is mounted on the vehicle is controlled through a control unit of the processor based on the object recognized by the object recognition unit.