Oil leakage detector and oil leakage detection method and image processing unit

Patent metadata

Field	Value
Publication number	US-10755442-B2
Application number	US-201815869508-A
Country	US
Kind code	B2
Filing date	Jan 12, 2018
Priority date	Mar 17, 2015
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

An oil leakage detector of the present invention includes an image processing unit wherein the image processing unit calculates the values of saturation and intensity of each pixel in the color image of the object after an ultra-violet light is irradiated thereon, draws an intensity-saturation characteristic line of the saturation expressed in an X-axis and the intensity expressed in a Y-axis, sets an upper limit and a lower limit of intensity of each saturation as a threshold value based on an area without oil adhesion on the surface of the object, and determines, in the intensity-saturation characteristic line, an area corresponding to a pixel group where the intensity exceeds the threshold value of the upper limit and a pixel group where the intensity falls below the threshold value of the lower limit, to be an oil leakage adhered area.

First claim

What is claimed is:

1. An oil leakage detector comprising:
an ultra-violet light irradiated on an object to be measured;
a color camera which photographs fluorescence from the object irradiated with the ultra-violet light;
a processing unit which determines an oil leakage by the image of the object photographed by the color camera; and
a display unit which displays a result of determination by the processing unit, wherein
the processing unit calculates the values of saturation and intensity, using the following expression:

Saturation
⁢

⁢

(
S
)

=

R
2

+

G
2

+

B
2

-
GR
-
BR
-
GB

1

Intensity
⁢

⁢

(
I
)

=

1
2

⁢
R

+

1
2

⁢
G

+

1
2

⁢
B

2

where R=red, G=green, and B=blue for each pixel, in the color image photographed by the color camera, and
determines the existence of an oil leak based on a relationship between the values of saturation and intensity and a threshold value.

2. The oil leakage detector according to claim 1 , wherein means for determining the area corresponding to the pixel group to be the oil leakage adhered area in the processing unit draws an intensity-saturation characteristic line of the saturation expressed in an X-axis and the intensity expressed in a Y-axis and determines, based on the intensity-saturation characteristic line, an area corresponding to a pixel group exceeding the threshold value of the upper limit of intensity, to be an oil leakage adhered area where R (Red), G (Green), and B (Blue) of each pixel indicative of the surface of the object photographed by the color camera satisfies a condition of R 2 +G 2 −BR−BG>0, or determines, based on the intensity-saturation characteristic line, an area corresponding to a pixel group falling below the threshold value of the lower limit of intensity, to be an oil leakage adhered area where the R, G, and B of the area of the object satisfies a condition of R 2 +G 2 −BR−BG<0.

3. The oil leakage detector according to claim 2 , wherein the processing unit draws the intensity-saturation characteristic line of the X-axis saturation and the Y-axis intensity by utilizing the area without oil adhesion on the surface of the object.

4. The oil leakage detector according to claim 2 , wherein the processing unit draws the intensity-saturation characteristic line of the X-axis saturation and the Y-axis intensity by utilizing the values of saturation and intensity obtained when the ultra-violet light irradiates the area without oil adhesion on the surface of the object with light having different intensities.

5. The oil leakage detector according to claim 2 , wherein the processing unit averages small values of intensity corresponding to each saturation where the R, G, and B of each pixel indicative of the surface of the object photographed by the color camera satisfies the condition of R 2 +G 2 −BR−BG>0, or averages large values of intensity corresponding to each saturation where the R, G, and B of each pixel indicative of the surface of the object photographed by the color camera satisfies the condition of R 2 +G 2 −BR−BG<0, and draws the intensity-saturation characteristic line of the X-axis saturation and the Y-axis intensity by using the average value of those.

6. The oil leakage detector according to claim 3 , wherein the setting of the area without oil adhesion on the surface of the object in the processing unit comprises setting a plurality of areas away from each other or setting an area having an area of such a degree as to include the areas away from each other.

7. The oil leakage detector according to claim 2 , wherein the area corresponding to the pixel group determined to be the oil leakage adhered area in the color image of the object is marked.

8. An oil leakage detection method comprising the steps of, when an oil leakage adhered area of an object to be measured is detected by an oil leakage detector including an ultra-violet light irradiated on the object, a color camera which photographs fluorescence from the object irradiated with the ultra-violet light, a processing unit which determines an oil leakage by the image of the object photographed by the color camera and a display unit which displays a result of determination by the processing unit:
calculating by the processing unit, the values of saturation and intensity in the color image photographed by the color camera for photographing the fluorescence from the object irradiated with the ultra-violet light;
determining the existence of an oil leak based on a relationship between the values of saturation and intensity and a threshold value, using the following expression:

Saturation
⁢

⁢

(
S
)

=

R
2

+

G
2

+

Assignees

• Hitachi Ltd

Inventors

• Lu Li
• Ichimura Satoshi
• Moriyama Tomohiro
• Nukaga Jun
• Rokunohe Toshiaki
• Yamagishi Akira
• Saito yasutomo

Classifications

• H04N23/84

  for processing colour signals · CPC title

• H04N23/10

  for generating image signals from different wavelengths · CPC title

• G06T2207/10024

  Color image · CPC title

• G06T7/90 Primary

  Determination of colour characteristics · CPC title

• G06T7/0004

  Industrial image inspection · CPC title