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Infrared Nondestructive Testing Seminar-March 16 2012
Image quality indexes for infrared nondestructive testing
Hernán Darío Benítez Restrepo
Pontificia Universidad Javeriana-Cali
Infrared Nondestructive Testing Seminar-March 16 2012
1. Introduction
2. Digital image processing techniques in Infrared Nondestructive Testing IRNDT
3. Image quality metrics
4. IRIQI (Infrared Image Quality Index)
5. Results and analysis
6. Conclusions and further work
7. Acknowledgements
Outline
Infrared Nondestructive Testing Seminar-March 16 2012
Introduction
Image acquisition Image processing
Image compression (i.e jpeg)
Transmitter Receiver
Image transmission Image display
Digital images are subject to a wide variety of distortionsany of which may result in a degradation of visual quality
Infrared Nondestructive Testing Seminar-March 16 2012
Introduction
Impulsive Salt-Pepper Noise
Original
Additive Gaussian Noise Blurring JPEG Compression
How to predict automatically and objectivelythe perceived visual quality of these images ?
Source: https://ece.uwaterloo.ca/~z70wang/research/quality_index/demo_goldhill.html
Infrared Nondestructive Testing Seminar-March 16 2012
An objective image quality metric can play a variety of roles in image processing applications:
1. Monitoring. i.e allocation of streaming resources in digital video server
2. Optimization of algorithms and parameters setting. i.e tuning of image filtering
3. Benchmarking of image processing systems and algorithms i.e comparison of infrared image processing techniques in terms of image quality.
Introduction
Infrared Nondestructive Testing Seminar-March 16 2012
Introduction
What is the ‘best’ technique to improve image quality ?
Original First derivative
Principal component analysis
Phase image
Image of maximumcontrast
Second derivative
Infrared Nondestructive Testing Seminar-March 16 2012
Introduction
Original Blurred image
Blurred image Original
Features of original image
Features of blurred image
Blurred image
Full reference
Relative reference
Reference free
Infrared Nondestructive Testing Seminar-March 16 2012
Digital image processing techniques in Infrared Nondestructive Testing IRNDT
Transmission
1
Reflection
3
6
Analysis
2
Sample 4
IR camera
5
IR images
Infrared Nondestructive Testing Seminar-March 16 2012
Thermal Contrast
Absolute contrast Ca
∆T = Ca = Td − Tnd
Normalized contrast Cn, tm
when the excess of temperature is maximal
∆T = Cn =Tdef (t)
Tdef (tm)− Ts(t)
Ts(tm)
50 100 150 200
50
100
150
200
250
Image of maximum normalized contrast (CFRP sample)
Digital image processing techniques in Infrared Nondestructive Testing IRNDT
Infrared Nondestructive Testing Seminar-March 16 2012
d
dtln(T ) =
N�
n=1
nanlnn−1(t)
d2
dt2ln(T ) =
N�
n=2
(n− 1)nanlnn−2(t)
First derivative
Second derivative
TSR (Thermographic Signal Reconstruction)
Digital image processing techniques in Infrared Nondestructive Testing IRNDT
a0 a1 a2 a3 a4
Infrared Nondestructive Testing Seminar-March 16 2012
Image quality metrics
UQI� �� �Universal Quality Index
=σAB
σAσB� �� �loss of correlation
∗ 2AB
(A)2 + (B)2� �� �luminance distortion
∗ 2σAσB
σ2A + σ2
B� �� �contrast distortion
SNR� �� �Signal To Noise Ratio
=| ∆T |
σnon−defective
A Universal Image Quality Index, Z. Wang and A. Bovik, IEEE SIGNAL PROCESSING LETTERS, VOL. 9, NO. 3, MARCH 2002
Defense and illustration of time-resolved pulsed thermography for NDE, D. Balageas, QIRT Journal Vol 1 2012.
B. Girod, “What’s wrong with mean-squared error,” in Digital Images and Human Vision, A. B. Watson, Ed. Cambridge, MA: MIT Press, 1993, pp. 207–220
MSE� �� �Mean Squared Error
=1
M ∗N�
M,N
(A(m,n)−B(m,n))2
Infrared Nondestructive Testing Seminar-March 16 2012
50 100 150 200
50
100
150
200
250
IRIQI (Infrared Image Quality Index)
Image processing technique
i.e (TSR, Thermal contrast)
X ∈ [X1, X2] Y ∈ [Y1, Y2]
E = Y −X
E
Defective (ND) area
Non Defective (D) area
LIQI� �� �Local Infrared Quality Index
=
�kn=1 | pD(n)− pND(n) |
�kn=1 | pD(n) | + | pND(n) |
CE����Contrast enhancement
= 1− 2σXσY
σ2X + σ2
Y� �� �contrast distortion
IRIQI = LIQI ∗ CE
Infrared Nondestructive Testing Seminar-March 16 2012
Results and analysisCFRP
(Carbon Fiber Reinforced Plastic)
Sampling frequency: 157 HzTime of acquisition: 6.3 s
Size of images sequence: 292 x 246 x 991
Defective area (1)
Defective area (2)
Sound area
Infrared Nondestructive Testing Seminar-March 16 2012
Results and analysisNormalized Thermal Contrast
Row 1 - Defective area (1) - depth= 0.2 mmRow 2 - Defective area (2) - depth= 1.0 mm
0 1 2 3 4 5 6 70.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Time(s)
Qua
lity
Inde
x [0
,1]
IRIQIUQI
0 1 2 3 4 5 6 720
10
0
10
20
30
40
Time(s)
dB
SNR
0 1 2 3 4 5 6 70.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Time(s)
Qua
lity
Inde
x [0
,1]
IRIQIUQI
0 1 2 3 4 5 6 720
10
0
10
20
30
40
Time(s)
dB
SNR
0 1 2 3 4 5 6 70
10
20
30
40
50
60
Time(s)
dB
MSE
0 1 2 3 4 5 6 70
10
20
30
40
50
60
Time(s)
dB
MSE
Infrared Nondestructive Testing Seminar-March 16 2012
Results and analysisTSR
Second derivativeRow 1 - Defective area (1) - depth= 0.2 mmRow 2 - Defective area (2) - depth= 1.0 mm
0 1 2 3 4 5 6 70.4
0.2
0
0.2
0.4
0.6
0.8
1
Time(s)
Qua
lity
Inde
x [0
,1]
IRIQIUQI
0 1 2 3 4 5 6 720
10
0
10
20
30
40
Time(s)
dB
SNR
0 1 2 3 4 5 6 70
10
20
30
40
50
60
Time(s)
dB
MSE
0 1 2 3 4 5 6 70.2
0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Time(s)
Qua
lity
Inde
x [0
,1]
IRIQIUQI
0 1 2 3 4 5 6 720
10
0
10
20
30
40
Time(s)
dB
SNR
0 1 2 3 4 5 6 70
10
20
30
40
50
60
Time(s)
dB
MSE
Infrared Nondestructive Testing Seminar-March 16 2012
Conclusions and further work
•Image quality assessment in IRNDT is important to objectively compare the visual results of techniques such as Pulsed Phase Thermography (PPT), TSR, thermal contrast, PCT (Principal Components Thermography), etc.
•IRIQI is self-reference and full- reference (i.e it needs the temperature image as reference).
•IRIQI can become a self-reference image quality index by comparing the contrast between defective and non-defective areas.
•IRIQI can become a global image quality index if statistical features are measured locally and then combined them together.
Infrared Nondestructive Testing Seminar-March 16 2012
Acknowledgements
•CIAM 2009-2012 (Colaboración Interamericana de Materiales)
•COLCIENCIAS
•MIVIM (Multipolar Infrared Vision Infrarouge Multipolaire) Research Chair Canada
Infrared Nondestructive Testing Seminar-March 16 2012
Thank you ! Questions ?