Banknote crack detection method and apparatus

Patent metadata

Field	Value
Publication number	US-10319172-B2
Application number	US-201515543551-A
Country	US
Kind code	B2
Filing date	Jul 13, 2015
Priority date	Jan 26, 2015
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

A banknote crack detection method and a banknote crack detection apparatus are provided. The banknote crack detection apparatus includes an image collection unit, configured to collect an optical transmission image of an inputted banknote, a pre-processing unit, configured to receive a banknote image signal collected by the image collection unit, and perform foreground region positioning and cutting on the banknote image signal; a crack detection unit, configured to detect whether a crack exists; and a determining unit, configured to determine whether the banknote is qualified according to a detection result of the crack detection unit; and a control unit, configured to control operation of each of the above units.

First claim

The invention claimed is:

1. A banknote crack detection method, comprising:
inputting a to-be-detected banknote;
collecting an optical transmission image of the inputted banknote;
detecting a foreground region of the inputted banknote, cutting the foreground region, and placing the foreground region in a pixel coordinate system;
determining whether there is a crack at an edge of the foreground region;
when it is determined that there is a crack at an edge of the foreground region, accumulating a crack edge length CL and a crack depth CH;
determining whether the crack edge length CL is greater than a preset threshold and whether the crack depth CH is greater than the preset threshold,
determining that the inputted banknote has a crack and rejecting the inputted banknote in a case that the crack edge length CL is greater than the preset threshold or the crack depth CH is greater than the preset threshold; and receiving, the inputted banknote in a case that the crack edge length CL is not greater than the preset threshold and the crack depth CH is not greater than the preset threshold,
wherein determining whether there is a crack at an edge of the foreground region comprises:
a first step of performing an initialization setting to set a starting edge point of the crack as P S , an end edge point of the crack as P E , a crack width as Cw=0, the crack edge length as Cl=0, and the crack depth as Ch=0;
a second step of searching for a crack starting edge point and a crack end edge point in pixels in an edge of the foreground region, and updating P S =P(x 01 , y 01 ), P E =P(x 02 , y 01 ), CL=Cl+2 and CH=Ch+1 in a case that points P(x 01 , y 01 ) and P(x 02 , y 01 ) meet:

{

x
02

-

x
01

-
1

<=
2

GrayP
⁡

(

x
01

,

y
01

)

<

gth
⁢

⁢
max

GrayP
⁡

(

x
02

,

y
01

)

<

gth
⁢

⁢
max

GrayP
M

>

gth
⁢

⁢
min

,

wherein P(x 01 , y 01 ) indicates a pixel point at a coordinate (x 01 , y 01 ) of the banknote foreground region image, GrayP (x 01 , y 01 ) indicates a gray value of the pixel point at the coordinate (x 01 , y 01 ), x 02 −x 01 −1<=2 indicates that a width of a crack region on the foreground region image is no more than 2 pixels, gth max denotes a maximum gray value of an optical transmission image when there is no crack in medium, and is generally set to 200, gth min denotes a minimum gray value of a crack region in the optical transmission image, and is generally set to 250, and P M denotes a point between P(x 01 , y 01 ) and P(x 02 , y 01 );
a third step of determining that

{

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02

=

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01

+
2

GrayP
⁡

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-
1

,

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01

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1

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⁢

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GrayP
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(

Assignees

• Grg Banking Equipment Co Ltd

Inventors

• Yu Yuanchao
• Wang Rongqiu
• Huang Zhanfeng

Classifications

• G06T7/11

  Region-based segmentation · CPC title

• G07D11/237 Primary

  for detecting transport malfunctions, e.g. jams or misfeeds · CPC title

• G07D7/181

  Testing mechanical properties or condition, e.g. wear or tear (G07D7/16 takes precedence) · CPC title

• G07D11/009

  Depositing devices · CPC title

• G06T7/0002

  Inspection of images, e.g. flaw detection · CPC title