Improvement of Crack Detection Probability by Using Magnetic Camera and Image Processing

2007 ◽  
Vol 353-358 ◽  
pp. 2375-2378 ◽  
Author(s):  
Se Ho Choi ◽  
Ji Seong Hwang ◽  
Jong Woo Jun ◽  
Jin Yi Lee ◽  
Cheol Woong Kim
Keyword(s):  
Image Processing ◽  
Detection Probability ◽  
Crack Detection ◽  
Mechanical Vibration ◽  
Processing Method ◽  
Magnetic Sensors ◽  
Magnetic Lens ◽  
Analog To Digital ◽  
Lift Off ◽  
Magnetic Camera

Magnetic camera consists of magnetic source, arrayed small magnetic sensors, magnetic lens, analog-to-digital converter and interface, computer and monitor. The quantitative magnetic field around crack and its processed results could be obtained by using magnetic camera, and the crack could be inspected and evaluated quantitatively. In addition, the magnetic camera has to uphold with large lift-off to protect sensors from weak environment such as high temperature and mechanical vibration. However, the sensor sensitivity would be decreased when the lift-off was increased. Correspondingly, the improved techniques are necessary for increasing sensitivity of magnetic camera and probability of crack detection at the large lift-off. This paper proposes an image processing method, which separates a global full scale to the several regions and repeats shadings in each region, to increase a crack detection probability in the magnetic camera images such as ∂B/∂x and ∂2B/∂x∂y.

THE QNDE USING IMAGE PROCESSING OF THE MAGNETIC CAMERA

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4625-4630 ◽  
Author(s):  
JINYI LEE ◽  
JISEONG HWANG ◽  
SEHO CHOI
Keyword(s):  
Image Processing ◽  
High Speed ◽  
Magnetic Hysteresis ◽  
High Sensitivity ◽  
Magnetic Sensors ◽  
Second Derivatives ◽  
Crack Volume ◽  
Lift Off ◽  
Magnetic Camera ◽  
Derivatives Of

A scan type magnetic camera was proposed to satisfy the following demands: to obtain high speed quantitative magnetic flux leakage (MFL) distribution with homogeneous lift-off by using 2-dimensionally arrayed high sensitivity magnetic sensors; to concentrate the MFL; and to ignore the residual magnetization and magnetic hysteresis by using a magnetic fluid lens. The magnetic field distribution (MFD) image obtained by using the scan type magnetic camera is inclined to the scanning direction (x-direction) because of the poles of the magnetizer. Also, the image shows a homogeneous trend relative to the x-direction, but there are small waves in the distribution in the sensor arraying direction (y-direction). The crack information in the MFD image can be extracted using image processing. The first and second derivatives of both x and y are used in this processing. These are "1st derivative of x, ∂B/∂x", "1st derivative of y, ∂B/∂y", "2nd derivative of x, ∂2B/∂x2", "2nd derivative of y, ∂2B/∂y2", and "2nd derivative of x and y, ∂2B/∂x∂y". The ∂B/∂x distribution shows the existence of the crack. Also, the crack volume can be evaluated quantitatively, regardless of the crack direction, by using ∂B/∂x and a cross type magnetic coil.

THE DETECTION PROBABILITY IMPROVEMENT OF THE FAR-SIDE CRACK ON THE HIGH LIFT-OFF USING THE MAGNETIC CAMERA

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4631-4636 ◽  
Author(s):  
JINYI LEE ◽  
JISEONG HWANG
Keyword(s):  
Magnetic Field ◽  
Crack Detection ◽  
Magnetic Lens ◽  
High Lift ◽  
Crack Volume ◽  
Detection Probabilities ◽  
Side Crack ◽  
Lift Off ◽  
Magnetic Camera ◽  
The Relationship

To evaluate cracks using magnetic flux leakage (MFL), the distribution of magnetic field (DMF) near the crack should be quantified. A narrow spatial resolution of DMF is demanded around the crack. Also the lift-off should increase over several mm to protect the sensors from environments such as high temperature, dust, and vibration. Furthermore, the MFL must be amplified to detect a far-side crack because the MFL will concentrate in the ferromagnetic specimen and will be weak. The magnetic camera and magnetic lens could be useful for high lift-off conditions such as in nondestructive testing of a far-side environment. The far-side crack detection probabilities, Max(∂B/∂x) and RMS(∂B/∂x), were improved by about 20~60% by using the magnetic lens. The crack can be easily detected by using the 1/4RMS algorithm. Finally, an equation that expresses the relationship between the volume of crack and Max(∂B/∂x) is proposed. This equation is based on the principle that the magnetic field is inversely proportional to the square of the lift-off and is useful for determining the crack volume when the lift-off is known.

scholarly journals Study of filming condition for deep learning based crack detection method

2021 ◽  
Author(s):  
Tomotaka Fukuoka ◽  
Takahiro Minami ◽  
Makoto Fujiu ◽  
Junichi Takayama
Keyword(s):  
Image Processing ◽  
Deep Learning ◽  
Service Life ◽  
Visual Inspection ◽  
Crack Detection ◽  
Detection Method ◽  
Processing Method ◽  
Inspection Method ◽  
Image Processing Method

Recently, the study of extending the service life of bridges has gained attention. In Japan, there are about 730,000 bridges with a length of 2 m or longer, and many of these were built during a period of high economic growth, and have now reached the end of their service life. Therefore, their rebuilding and the extension of their service life must be considered. However, some local public organizations have problems that insufficient manpower relative to the number of bridges to manage, as well as insufficient funding for maintenance. Thus, these organizations are unable to perform routine close visual inspections. Specific problems include “notably less staff and consulting technicians relative to the number of bridges to be managed” and “high inspection cost preventing from funding for repair.” As issues with the continuing close visual inspection of bridges are surfacing, the remote imaging system is expected to become a new inspection method that replaces close visual inspection. The practical potential of bridge inspections using images captured with a super-high-resolution camera was examined. A super-high-resolution camera enables us to take a wide area picture of a target bridge from a long distance. An image processing method could improve the efficiency of image-based inspection method. For example, a deep learning-based image processing method could extract a damaged area on a surface of a bridge automatically with high accuracy faster than human inspection. In general, the accuracy of an image processing method is affected by the quality of an input image. Filming conditions are one of the factors that determine the quality of a photo image. It is important to evaluate the effect of filming conditions to improve the reliability of an image processing method. In this paper, we evaluate the effect of the filming conditions for an image processing method by comparing the results of a deep learning-based crack detection method.

A Study of the Quantitative Nondestructive Evaluation Using the Cross Type Magnetic Source and the Magnetic Camera

2006 ◽  
Vol 321-323 ◽  
pp. 1447-1450 ◽  
Author(s):  
Jin Yi Lee ◽  
Ji Seong Hwang
Keyword(s):  
Nondestructive Evaluation ◽  
Magnetic Lens ◽  
Magnetization Direction ◽  
High Lift ◽  
Magnetic Source ◽  
Crack Volume ◽  
Lift Off ◽  
Magnetic Camera ◽  
Flux Leakage ◽  
Cross Type

The magnetic camera using magnetic lens is proposed to satisfy the demands such as obtaining the distribution of the magnetic flux leakage (DMFL) on the high lift-off, and improving sensitivity. However, DMFL is strongly affected by the magnetization direction. Therefore, the DMFL has low intensity when the crack is not perpendicular to the magnetizing direction. Also, quantitative nondestructive evaluation would be difficult. This paper proposes an improved magnetization method to evaluate a crack quantitatively, regardless of the crack direction. The secondary magnetic source, which is perpendicular to the primary magnetic source, is introduced in the scan type magnetic camera. The intensity of two values of ∂B/∂x (1st differential to the magnetization direction) of the DMFL can be used to evaluate the crack volume. The experimental and the numerical analysis results are considered to verify this phenomenon.

Detection Probability Improvement for Nondestructive Evaluation Using a Magnetic Camera

2006 ◽  
Vol 306-308 ◽  
pp. 241-246 ◽  
Author(s):  
Jin Yi Lee ◽  
Ji Seoung Hwang ◽  
Se Ho Choi ◽  
Jae Kyoo Lim
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Nondestructive Evaluation ◽  
Magnetic Fluid ◽  
Probability Of Detection ◽  
Magnetic Method ◽  
Magnetic Lens ◽  
3 Dimensional ◽  
Lift Off ◽  
Magnetic Camera

It is important to estimate the intensity distribution of a magnetic field as a possible magnetic method in an industrial nondestructive evaluation application. A magnetic camera provides the distribution of a quantitative magnetic field with homogeneous lift-off and same spatial resolution. Magnetic flux leakage near a crack on the specimen can be amplified by using a 3- dimensional magnetic fluid, that is to say a magnetic lens. This study introduces the experimental consideration of the effects of magnetic lenses for concentrating of magnetic flux. The experimental results showed that the magnetic fluid has a sufficient lens effect for magnetic camera and effect of improvement in probability of detection.

Crosstalk Minimization Method for Eye-tracking-based 3D Display

2020 ◽  
Author(s):  
Seok Lee ◽  
Juyong Park ◽  
Dongkyung Nam
Keyword(s):  
Image Processing ◽  
Eye Tracking ◽  
Three Dimensional ◽  
Processing Method ◽  
Eye Position ◽  
Relative Location ◽  
3D Display ◽  
Minimization Method ◽  
3D Crosstalk ◽  
Pixel Value

In this article, the authors present an image processing method to reduce three-dimensional (3D) crosstalk for eye-tracking-based 3D display. Specifically, they considered 3D pixel crosstalk and offset crosstalk and applied different approaches based on its characteristics. For 3D pixel crosstalk which depends on the viewer’s relative location, they proposed output pixel value weighting scheme based on viewer’s eye position, and for offset crosstalk they subtracted luminance of crosstalk components according to the measured display crosstalk level in advance. By simulations and experiments using the 3D display prototypes, the authors evaluated the effectiveness of proposed method.

Sign in / Sign up

Export Citation Format

Share Document