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Basler acA645-100gm
Camera SpecificationMeasurement protocol using the EMVA Standard 1288
Document Number: BD000636
Version: Preliminary
Release Date: June 21, 2012
PRELIMINARY VERSION
For customers in the U.S.A.
This equipment has been tested and found to comply with the limits for a Class A digital device,pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protec-tion against harmful interference when the equipment is operated in a commercial environment.This equipment generates, uses, and can radiate radio frequency energy and, if not installedand used in accordance with the instruction manual, may cause harmful interference to radiocommunications. Operation of this equipment in a residential area is likely to cause harmful in-terference in which case the user will be required to correct the interference at his own expense.
You are cautioned that any changes or modifications not expressly approved in this manualcould void your authority to operate this equipment.
The shielded interface cable recommended in this manual must be used with this equipment inorder to comply with the limits for a computing device pursuant to Subpart J of Part 15 of FCCRules.
For customers in Canada
This apparatus complies with the Class A limits for radio noise emissions set out in RadioInterference Regulations.
Pour utilisateurs au Canada
Cet appareil est conforme aux normes Classe A pour bruits radioelectriques, specifiees dans leReglement sur le brouillage radioelectrique.
Life Support Applications
These products are not designed for use in life support appliances, devices, or systems wheremalfunction of these products can reasonably be expected to result in personal injury. Baslercustomers using or selling these products for use in such applications do so at their own riskand agree to fully indemnify Basler for any damages resulting from such improper use or sale.
Warranty Note
Do not open the housing of the camera. The warranty becomes void if the housing is opened.
All material in this publication is subject to change without notice and is copyright BaslerVision Technologies.
Contacting Basler Support Worldwide
Europe:
Basler AG
An der Strusbek 60 - 62
22926 Ahrensburg
Germany
Tel.: +49-4102-463-500
Fax.: +49-4102-463-599
Americas:
Basler, Inc.
855 Springdale Drive, Suite 160
Exton, PA 19341
U.S.A.
Tel.: +1-877-934-8472
Fax.: +1-610-280-7608
Asia:
Basler Asia Pte. Ltd
8 Boon Lay Way
# 03 - 03 Tradehub 21
Singapore 609964
Tel.: +65-6425-0472
Fax.: +65-6425-0473
www.baslerweb.com
PRELIMINARY VERSION CONTENTS
Contents
1 Overview 7
2 Introduction 8
3 Basic Information 93.1 Illumination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.1 Illumination Setup for the Basler Camera Test Tool . . . . . . . . . 103.1.2 Measurement of the Irradiance . . . . . . . . . . . . . . . . . . . . 10
4 Characterizing Temporal Noise and Sensitivity 114.1 Basic Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1.1 Total Quantum Efficiency . . . . . . . . . . . . . . . . . . . . . . . 114.1.2 Temporal Dark Noise . . . . . . . . . . . . . . . . . . . . . . . . . . 134.1.3 Dark Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144.1.4 Doubling Temperature . . . . . . . . . . . . . . . . . . . . . . . . . 144.1.5 Inverse of Overall System Gain . . . . . . . . . . . . . . . . . . . . 154.1.6 Inverse Photon Transfer . . . . . . . . . . . . . . . . . . . . . . . . 164.1.7 Saturation Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . 174.1.8 Spectrogram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184.1.9 Non-Whiteness Coefficient . . . . . . . . . . . . . . . . . . . . . . 21
4.2 Derived Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.2.1 Absolute Sensitivity Threshold . . . . . . . . . . . . . . . . . . . . 224.2.2 Signal-to-noise Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . 234.2.3 Dynamic Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.3 Raw Measurement Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264.3.1 Mean Gray Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264.3.2 Variance of the Temporal Distribution of Gray Values . . . . . . . . 274.3.3 Mean of the Gray Values Dark Signal . . . . . . . . . . . . . . . . 284.3.4 Variance of the Gray Value Temporal Distribution in Darkness . . . 294.3.5 Light Induced Variance of the Temporal Distribution of Gray Values 304.3.6 Light Induced Mean Gray Value . . . . . . . . . . . . . . . . . . . . 314.3.7 Dark Current Versus Housing Temperature . . . . . . . . . . . . . 32
5 Characterizing Total and Spatial Noise 335.1 Basic Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.1.1 Spatial Offset Noise . . . . . . . . . . . . . . . . . . . . . . . . . . 335.1.2 Spatial Gain Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . 345.1.3 Spectrogram Spatial Noise . . . . . . . . . . . . . . . . . . . . . . 355.1.4 Spatial Non-whiteness Coefficient . . . . . . . . . . . . . . . . . . 38
5.2 Raw Measurement Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395.2.1 Standard Deviation of the Spatial Dark Noise . . . . . . . . . . . . 395.2.2 Light Induced Standard Deviation of the Spatial Noise . . . . . . . 40
Basler acA645-100gm 5
CONTENTS PRELIMINARY VERSION
Bibliography 41
6 Basler acA645-100gm
PRELIMINARY VERSION 1 Overview
1 Overview
Basler acA645-100gm
Item Symbol Typ.1 Unit Remarks
Temporal Noise Parameters
Total Quantum Efficiency (QE) η 37 % λ = 545 nm
Inverse of Overall System Gain 1K 6.2 e−
DN
Temporal Dark Noise σd0 21 e−
Saturation Capacity µe.sat 24200 e−
Derived Parameters
Absolute Sensitivity Threshold µp.min 57 p∼ λ = 545 nm
Dynamic Range DYNout.bit 10.2 bit
Maximum SNR SNRy.max.bit 7.3 bit
SNRy.max.dB 43.8 dB
Item Symbol Typ. Unit Remarks
Spatial Noise Parameters
Spatial Offset Noise, DSNU1288 σo 6.0 e−
Spatial Gain Noise, PRNU1288 Sg 1.1 %
Table 1: Most Important Specification Data
Operating Point
Item Symbol Remarks
Video output format 12 bits/pixel
Gain Register raw 200
Offset Register raw 66
Exposure time Texp 20.0µs to 12.2ms
Table 2: Operating Point for the Camera Used
1The unit e− is used in this document as a statistically measured quantity.
Basler acA645-100gm 7
2 Introduction PRELIMINARY VERSION
2 Introduction
This measurement protocol describes the specification of Basler acA645-100gm cam-eras. The measurement methods conform to the 1288 EMVA Standard, the Standardfor Characterization and Presentation of Specification Data for Image Sensors andCameras (Release A1.03) of the European Machine Vision Association (EMVA) [1].
The most important specification data for Basler acA645-100gm cameras is sum-marized in table 1.
8 Basler acA645-100gm
PRELIMINARY VERSION 3 Basic Information
3 Basic Information
Basic Information
Vendor Basler
Model acA645-100gm
Type of data presented Typical
Number of samples 70
Sensor Sony ICX414AL
Sensor type CCD
Sensor diagonal Diagonal 8 mm , Optical Size 1/2”
Indication of lens category to be used C-Mount
Resolution 659 x 490 pixel
Pixel width 9.90 µm
Pixel height 9.90 µm
Readout type Progressive scan
Transfer type Interline transfer
Shutter type -
Overlap capabilities Overlapping
Maximum readout rate 100 frames/second
General conventions -
Interface type Gigabit Ethernet
Table 3: Basic Information
Basler acA645-100gm 9
3.1 Illumination PRELIMINARY VERSION
3.1 Illumination
3.1.1 Illumination Setup for the Basler Camera Test Tool
The illumination during the testing on each camera was fixed. The drift in the illumina-tion over a long period of time and after the lamp is changed is measured by a referenceBasler A602fc camera. The reference camera provides an intensity factor that was usedto calculate the irradiance for each camera measurement.
Light Source
Item Symbol Typ. Unit Remarks
Wavelength λ 545 nm
Wavelength Variation ∆λ 50 nm
Distance sensor to light source d 280 mm
Diameter of the light source D 35 mm
f-Number f# 8 f# = dD
Table 4: Light Source
3.1.2 Measurement of the Irradiance
The irradiance was measured using an IL1700 Radiometer from International Light Inc.(Detector: SEL033 #6285; Input optic: W #9461; Filter: F #21487; regular calibration).The accuracy of the Radiometer is specified as ±3.5%.
The measured irradiance is plotted in figure 1.
50x10-3
40
30
20
10
0
Irra
dian
ce [W
/m^2
]
706050403020100
Measurement
'acA645-100gm' (70 cameras), Irradiance
Figure 1: Irradiance for Each Camera Measurement.
The error for each calculated value using the amount of light falling on the sensor isdependent on the accuracy of the irradiance measurement.
10 Basler acA645-100gm
PRELIMINARY VERSION 4 Characterizing Temporal Noise and Sensitivity
4 Characterizing Temporal Noise and Sensitivity
4.1 Basic Parameters
4.1.1 Total Quantum Efficiency
Total Quantum Efficiency for One Fixed Wavelength Total quantum efficiency η(λ)in [%] for monochrome light at λ = 545 nm with a wavelength variation of ∆λ = 50 nm.
40
30
20
10
0
Qua
ntum
Effi
cien
cy [%
]
706050403020100
Camera
'acA645-100gm' (70 cameras), Quantum Efficiency
16
14
12
10
8
6
4
2
0
Num
ber
38.538.037.537.036.536.0
Quantum Efficiency [%]
'acA645-100gm' (70 cameras), Quantum Efficiency Histogram
Figure 2: Total Quantum Efficiency (QE)
Item Symbol Typ. Std. Dev. Unit Remarks
Total Quantum Efficiency (QE) η 37 TBD % λ = 545 nm
Table 5: Total Quantum Efficiency (QE)
The main error in the total quantum efficiency ∆η is related to the error in the mea-surement of the illumination as described in section 3.1.
Basler acA645-100gm 11
4.1 Basic Parameters PRELIMINARY VERSION
Total Quantum Efficiency Versus Wavelength of the Light Total quantum effi-ciency η(λ) in [%] for monochrome light versus wavelength of the light in [nm] .
50
40
30
20
10
0
Qua
ntum
Effi
cien
cy [%
]
1000900800700600500400
Wavelength [nm]
'acA645-100gm', Quantum Efficiency
Figure 3: Total Quantum Efficiency Versus Wavelength of the Light
The curve of the total quantum efficiency versus the wavelength as shown in figure3 was calculated from the single measured total quantum efficiency as presented insection 4.1.1. For the shape of the curve, the data from the sensor data sheet wasused.
12 Basler acA645-100gm
PRELIMINARY VERSION 4.1 Basic Parameters
4.1.2 Temporal Dark Noise
Standard deviation of the temporal dark noise σd0 referenced to electrons for exposuretime zero in [ e−].
25
20
15
10
5
0
Std
. Dev
. Tem
pora
l Dar
k N
oise
[e-]
706050403020100
Camera
'acA645-100gm' (70 cameras), Std. Dev. Temporal Dark Noise
20
15
10
5
0
Num
ber
22.021.521.020.5
Std. Dev. Temporal Dark Noise [e-]
'acA645-100gm' (70 cameras), Std. Dev. Temporal Dark Noise Histogram
Figure 4: Temporal Dark Noise
Item Symbol Typ. Std. Dev. Unit Remarks
Temporal Dark Noise σd0 21 0.4 e−
Table 6: Temporal Dark Noise
Basler acA645-100gm 13
4.1 Basic Parameters PRELIMINARY VERSION
4.1.3 Dark Current
Dark current Nd30 for a housing temperature of 30◦ C in [e−/s] .Not measured!
4.1.4 Doubling Temperature
Doubling temperature kd of the dark current in [◦ C].Not measured!
14 Basler acA645-100gm
PRELIMINARY VERSION 4.1 Basic Parameters
4.1.5 Inverse of Overall System Gain
Inverse of overall system gain 1K
in [ e−DN
].
7
6
5
4
3
2
1
0
Inve
rse
of O
vera
ll S
yste
m G
ain
[e-/
DN
]
706050403020100
Camera
'acA645-100gm' (70 cameras), Inverse of Overall System gain
16
12
8
4
0
Num
ber
6.356.306.256.206.15
Inverse of Overall System Gain [e-/DN]
'acA645-100gm' (70 cameras), Inverse of Overall System Gain Histogram
Figure 5: Inverse of Overall System Gain
Item Symbol Typ. Std. Dev. Unit Remarks
Inverse of Overall System Gain 1K 6.2 0.06 e−
DN
Table 7: Inverse of Overall System Gain
Basler acA645-100gm 15
4.1 Basic Parameters PRELIMINARY VERSION
4.1.6 Inverse Photon Transfer
Inverse photon transfer 1ηK
in[
p∼DN
].
16
12
8
4
0Inve
rse
Pho
ton
Tra
nsfe
r [p
~/D
N]
706050403020100
Camera
'acA645-100gm' (70 cameras), Inverse Photon Transfer
16
14
12
10
8
6
4
2
0
Num
ber
17.217.016.816.616.416.2
Inverse Photon Transfer [e-/DN]
'acA645-100gm' (70 cameras), Inverse Photon Transfer Histogram
Figure 6: Inverse Photon Transfer
Item Symbol Typ. Std. Dev. Unit Remarks
Inverse Photon Transfer 1ηK 16.8 TBD p∼
DN λ = 545 nm
Table 8: Inverse Photon Transfer
The main error in the inverse photon transfer 1ηK
is related to the error in the mea-surement of the illumination as described in section 3.1.
16 Basler acA645-100gm
PRELIMINARY VERSION 4.1 Basic Parameters
4.1.7 Saturation Capacity
Saturation capacity µe.sat referenced to electrons in [ e−].
25000
20000
15000
10000
5000
0
Sat
urat
ion
Cap
acity
[e-]
706050403020100
Camera
'acA645-100gm' (70 cameras), Saturation Capacity
16
14
12
10
8
6
4
2
0
Num
ber
2460024400242002400023800
Saturation Capacity [e-]
'acA645-100gm' (70 cameras), Saturation Capacity Histogram
Figure 7: Saturation Capacity
Item Symbol Typ. Std. Dev. Unit Remarks
Saturation Capacity µe.sat 24200 240 e−
Table 9: Saturation Capacity
Basler acA645-100gm 17
4.1 Basic Parameters PRELIMINARY VERSION
4.1.8 Spectrogram
Spectrogram referenced to photons in [p∼] is plotted versus spatial frequency in [1/pixel]for no light, 50% saturation, and 90% saturation.
140
120
100
80
60
40
20
0
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), FFT for No Light
All Mean
5
6
7
8
9
100
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), FFT for No Light
All Mean
Figure 8: Spectrogram Referenced to Photons for No Light
18 Basler acA645-100gm
PRELIMINARY VERSION 4.1 Basic Parameters
7000
6000
5000
4000
3000
2000
1000
0
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), FFT for 50% Saturation
All Mean
3
456
1000
2
3
456
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), FFT for 50% Saturation
All Mean
Figure 9: Spectrogram Referenced to Photons for 50% Saturation
Basler acA645-100gm 19
4.1 Basic Parameters PRELIMINARY VERSION
14000
12000
10000
8000
6000
4000
2000
0
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), FFT for 90% Saturation
All Mean
4
6
810
3
2
4
6
810
4
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), FFT for 90% Saturation
All Mean
Figure 10: Spectrogram Referenced to Photons for 90% Saturation
20 Basler acA645-100gm
PRELIMINARY VERSION 4.1 Basic Parameters
4.1.9 Non-Whiteness Coefficient
The non-whiteness coefficient is plotted versus the number of photons µp in [p∼] col-lected in a pixel during exposure time.
6
5
4
3
2
1
0
Non
Whi
tene
ss
800006000040000200000
Mean Photon [Photons/pixel]
'acA645-100gm' (70 cameras), Non Whiteness
Figure 11: Non-whiteness Coefficient
Basler acA645-100gm 21
4.2 Derived Data PRELIMINARY VERSION
4.2 Derived Data
4.2.1 Absolute Sensitivity Threshold
Absolute sensitivity threshold µp.min(λ) in [ p∼] for monochrome light versus wavelengthof the light in [nm] .
µp.min =σd0
η(1)
70
60
50
40
30
20
10
0Abs
olut
e S
ensi
tivity
Thr
esho
ld [p
~]
706050403020100
Camera
'acA645-100gm' (70 cameras), Absolute Sensitivity Threshold
16
14
12
10
8
6
4
2
0
Num
ber
60595857565554
Absolute Sensitivity Threshold [p~]
'acA645-100gm' (70 cameras), Absolute Sensitivity Threshold Histogram
Figure 12: Absolute Sensitivity Threshold
Item Symbol Typ. Std. Dev. Unit Remarks
Absolute Sensitivity Threshold µp.min 57 TBD p∼ λ = 545 nm
Table 10: Absolute Sensitivity Threshold
22 Basler acA645-100gm
PRELIMINARY VERSION 4.2 Derived Data
4.2.2 Signal-to-noise Ratio
Signal-to-noise ratio SNRy(µp) is plotted versus number of photons µp collected in apixel during exposure time in [p∼] for monochrome light with the wavelength λ given in[ nm]. The wavelength should be near the maximum of the quantum efficiency.
A : SNRy =µy − µy.dark
σy
(2)
B : SNRy =ηµp√
(ηµp + σ2d0
)(3)
Figure 13 shows the signal-to-noise ratio SNRy for monochrome light with the wave-length λ = 545 nm.
8
6
4
2
0
SN
R [b
it]
1614121086420
Mean Photon [bit]
'acA645-100gm' (70 cameras), SNR
A B
Figure 13: Signal-to-noise Ratio
The maximum achievable image quality is given as SNRy.max .
SNRy.max =√
µe.sat (4)
SNRy.max.bit = ld SNRy.max =log SNRy.max
log 2(5)
SNRy.max.dB = 20 log SNRy.max ≈ 6.02 SNRy.max.bit (6)
Basler acA645-100gm 23
4.2 Derived Data PRELIMINARY VERSION
1
2
46
10
2
46
100
2
4
SN
R
100
101
102
103
104
105
Mean Photon [Photons/pixel]
'acA645-100gm' (70 cameras), SNR
A B
Figure 14: Signal-to-noise Ratio
Item Symbol Typ. Std. Dev. Unit Remarks
Maximum achievable SNR [bit] SNRy.max.bit 7.3 0.01 bit
Table 11: Maximum achievable SNR [bit]
Item Symbol Typ. Std. Dev. Unit Remarks
Maximum achievable SNR [dB] SNRy.max.dB 43.8 0.04 dB
Table 12: Maximum achievable SNR [dB]
24 Basler acA645-100gm
PRELIMINARY VERSION 4.2 Derived Data
4.2.3 Dynamic Range
Dynamic range DYNout.bit in [ bit].
DYNout =µe.sat
σd0
(7)
DYNout.bit = log2 (DYNout) (8)
12
10
8
6
4
2
0
Out
put D
ynam
ic R
ange
[bit]
706050403020100
Camera
'acA645-100gm' (70 cameras), Output Dynamic Range
14
12
10
8
6
4
2
0
Num
ber
10.1810.1610.1410.1210.10
Output Dynamic Range [bit]
'acA645-100gm' (70 cameras), Output Dynamic Range Histogram
Figure 15: Output Dynamic Range
Item Symbol Typ. Std. Dev. Unit Remarks
Output Dynamic Range DYNout.bit 10.2 0.03 bit
Table 13: Output Dynamic Range
Basler acA645-100gm 25
4.3 Raw Measurement Data PRELIMINARY VERSION
4.3 Raw Measurement Data
4.3.1 Mean Gray Value
Mean gray value µy(µp) in [DN] is plotted versus number of photons µp in [p∼] collectedin a pixel during exposure time.
5000
4000
3000
2000
1000
0
Mea
n G
ray
Val
ue B
right
[DN
]
800006000040000200000
Mean Photon [Photons/pixel]
'acA645-100gm' (70 cameras), Mean Gray Value Bright
Figure 16: Mean Gray Values of the Cameras with Illuminated Pixels
26 Basler acA645-100gm
PRELIMINARY VERSION 4.3 Raw Measurement Data
4.3.2 Variance of the Temporal Distribution of Gray Values
The variance of the temporal distribution of gray values σ2y.temp(µp) in [DN2] is plotted
versus number of photons µp in [p∼] collected in a pixel during exposure time.
700
600
500
400
300
200
100
0Var
ianc
e G
ray
Val
ue B
right
[DN
^2]
800006000040000200000
Mean Photon [Photons/pixel]
'acA645-100gm' (70 cameras), Variance Gray Value Bright
Figure 17: Variance Values for the Temporal Distribution of Gray Values with IlluminatedPixels
Saturation Capacity The saturation point is defined as the maximum of the curve infigure 17. The abscissa of the maximum point is the number of photons µp.sat where thecamera saturates. The saturation capacity µe.sat in electrons is computed according tothe mathematical model as:
µe.sat = ηµp.sat (9)
Basler acA645-100gm 27
4.3 Raw Measurement Data PRELIMINARY VERSION
4.3.3 Mean of the Gray Values Dark Signal
Mean of the gray values dark signal µy.dark(Texp) in [DN] is plotted versus exposuretime in [s] .
16
12
8
4
0
Mea
n G
ray
Val
ue D
ark
[DN
]
121086420
Exposure Time [ms]
'acA645-100gm' (70 cameras), Mean Gray Value Dark
Figure 18: Mean Gray Values for the Cameras in Darkness
28 Basler acA645-100gm
PRELIMINARY VERSION 4.3 Raw Measurement Data
4.3.4 Variance of the Gray Value Temporal Distribution in Darkness
The variance of the temporal distribution of gray values in darkness σ2y.temp.dark(Texp) in
[DN2] is plotted versus exposure time Texp in [s] .
14
12
10
8
6
4
2
0Var
ianc
e G
ray
Val
ue D
ark
[DN
^2]
121086420
Exposure Time [ms]
'acA645-100gm' (70 cameras), Variance Gray Value Dark
Figure 19: Variance Values for the Temporal Distribution of Gray Values in Darkness
Temporal Dark Noise The dark noise for exposure time zero is found as the offset ofthe linear correspondence in figure 19. Match a line (with offset) to the linear part of thedata in the diagram. The dark noise for exposure time zero σ2
d0is found as the offset of
the line divided by the square of the overall system gain K.
σd0 =
√σ2
y.temp.dark(Texp = 0)
K2(10)
Basler acA645-100gm 29
4.3 Raw Measurement Data PRELIMINARY VERSION
4.3.5 Light Induced Variance of the Temporal Distribution of Gray Values
The light induced variance of the temporal distribution of gray values in [DN2] is plottedversus light induced mean gray value in [DN] .
600
500
400
300
200
100
0
Var
ianc
e G
ray
Val
ue (
Brig
ht -
Dar
k) [D
N^2
]
3500300025002000150010005000
Mean Gray Value (Bright - Dark) [DN]
'acA645-100gm' (70 cameras), Diff. Variance vs Diff. Mean Gray Value
Figure 20: Light Induced Variance of the Temporal Distribution of Gray Values VersusLight Induced Mean Gray Value
Overall System Gain The overall system gain K is computed according to the math-ematical model as:
K =σ2
y.temp − σ2y.temp.dark
µy − µy.dark
(11)
which describes the linear correspondence in figure 20. Match a line starting at theorigin to the linear part of the data in this diagram. The slope of this line is the overallsystem gain K.
30 Basler acA645-100gm
PRELIMINARY VERSION 4.3 Raw Measurement Data
4.3.6 Light Induced Mean Gray Value
The light induced mean gray value µy − µy.dark in [ DN] is plotted versus the number ofphotons collected in a pixel during exposure time Kµp in [ p ∼].
4000
3500
3000
2500
2000
1500
1000
500
0
Mea
n G
ray
Val
ue (
Brig
ht -
Dar
k) [D
N]
6000050000400003000020000100000
Mean Photon [Photons/pixel]
'acA645-100gm' (70 cameras), Difference Mean Gray Value
Figure 21: Light Induced Mean Gray Value Versus the Number of Photons
Total Quantum Efficiency The total quantum efficiency η is computed according tothe mathematical model as:
η =µy − µy.dark
Kµp
(12)
which describes the linear correspondence in figure 21. Match a line starting at theorigin to the linear part of the data in this diagram. The slope of this line divided by theoverall system gain K yields the total quantum efficiency η.
The number of photons µp is calculated using the model for monochrome light. Thenumber of photons Φp collected in the geometric pixel per unit exposure time [p∼/s] isgiven by:
Φp =EAλ
hc(13)
with the irradiance E on the sensor surface [W/m2] , the area A of the (geometrical)pixel [m2] , the wavelength λ of light [m] , the Planck’s constant h ≈ 6.63 · 10−34 Js, andthe speed of light c ≈ 3 · 108 m/s. The number of photons can be calculated by:
µp = ΦpTexp (14)
during the exposure time Texp. Using equation 12 and the number of photons µp, thetotal quantum efficiency η can be calculated as:
η =hc
ATexp
1
E
1
λ
µp − µy.dark
K. (15)
Basler acA645-100gm 31
4.3 Raw Measurement Data PRELIMINARY VERSION
4.3.7 Dark Current Versus Housing Temperature
The logarithm to the base 2 of the dark current in [e−/s] versus deviation of the housingtemperature from 30◦C in [ ◦ C]
Not measured!
32 Basler acA645-100gm
PRELIMINARY VERSION 5 Characterizing Total and Spatial Noise
5 Characterizing Total and Spatial Noise
5.1 Basic Parameters
5.1.1 Spatial Offset Noise
Standard deviation of the spatial offset noise σo referenced to electrons in [ e−].
7
6
5
4
3
2
1
0
DS
NU
1288
[e-]
706050403020100
Camera
'acA645-100gm' (70 cameras), DSNU1288
16
14
12
10
8
6
4
2
0
Num
ber
6.26.05.85.6
DSNU1288 [e-]
'acA645-100gm' (70 cameras), DSNU1288 Histogram
Figure 22: Spatial Offset Noise ( DSNU1288 )
Item Symbol Typ. Std. Dev. Unit Remarks
Spatial Offset Noise ( DSNU1288 ) σo 6.0 0.2 e−
Table 14: Spatial Offset Noise ( DSNU1288 )
Basler acA645-100gm 33
5.1 Basic Parameters PRELIMINARY VERSION
5.1.2 Spatial Gain Noise
Standard deviation of the spatial gain noise Sg in [ %].
2.5
2.0
1.5
1.0
0.5
0.0
PR
NU
1288
[%]
706050403020100
Camera
'acA645-100gm' (70 cameras), PRNU1288
35
30
25
20
15
10
5
0
Num
ber
2.01.81.61.41.21.0
PRNU1288 [%]
'acA645-100gm' (70 cameras), PRNU1288 Histogram
Figure 23: Spatial Gain Noise ( PRNU1288 )
Item Symbol Typ. Std. Dev. Unit Remarks
Spatial Gain Noise ( PRNU1288 ) Sg 1.1 0.2 %
Table 15: Spatial Gain Noise ( PRNU1288 )
34 Basler acA645-100gm
PRELIMINARY VERSION 5.1 Basic Parameters
5.1.3 Spectrogram Spatial Noise
Spectrogram referenced to photons in [p∼] is plotted versus spatial frequency in [1/pixel]for no light, 50% saturation, and 90% saturation.
60
50
40
30
20
10
0
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), Spatial FFT for No Light
All Mean
2x101
3
4
5
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), Spatial FFT for No Light
All Mean
Figure 24: Spectrogram Referenced to Photons for No Light
Basler acA645-100gm 35
5.1 Basic Parameters PRELIMINARY VERSION
7000
6000
5000
4000
3000
2000
1000
0
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), Spatial FFT for 50% Saturation
All Mean
100
2
4
68
1000
2
4
6
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), Spatial FFT for 50% Saturation
All Mean
Figure 25: Spectrogram Referenced to Photons for 50% Saturation
36 Basler acA645-100gm
PRELIMINARY VERSION 5.1 Basic Parameters
14000
12000
10000
8000
6000
4000
2000
0
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), Spatial FFT for 90% Saturation
All Mean
2
4
68
103
2
4
68
104
FF
T A
mpl
itude
[p~
]
0.50.40.30.20.10.0
Frequency [Cycles/pixel]
'acA645-100gm' (70 cameras), Spatial FFT for 90% Saturation
All Mean
Figure 26: Spectrogram Referenced to Photons for 90% Saturation
Basler acA645-100gm 37
5.1 Basic Parameters PRELIMINARY VERSION
5.1.4 Spatial Non-whiteness Coefficient
The non-whiteness coefficient is plotted versus the number of photons µp in [p∼] col-lected in a pixel during exposure time.
20
15
10
5
0
Spa
tial N
on-W
hite
ness
6000050000400003000020000100000
Mean Photon [Photons/pixel]
'acA645-100gm' (70 cameras), Spatial Non-Whiteness
Figure 27: Spatial Non-whiteness Coefficient
38 Basler acA645-100gm
PRELIMINARY VERSION 5.2 Raw Measurement Data
5.2 Raw Measurement Data
5.2.1 Standard Deviation of the Spatial Dark Noise
Standard deviation of the spatial dark noise in [DN] versus exposure time in [s] .
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Spa
tial S
td. D
ev. G
ray
Val
ue D
ark
[DN
]
86420
Exposure Time [ms]
'acA645-100gm' (70 cameras), Spatial Std. Dev. Gray Value Dark
Figure 28: Standard Deviation of the Spatial Dark Noise
From the mathematical model, it follows that the variance of the spatial offsetnoise σ2
o should be constant and not dependent on the exposure time. Check that thedata in the figure 28 forms a flat line. Compute the mean of the values in the diagram.The mean divided by the conversion gain K gives the standard deviation of the spatialoffset noise σo .
DSNU1288 = σo =σy.spat.dark
K(16)
The square of the result equals the variance of the spatial offset noise σ2o .
Basler acA645-100gm 39
5.2 Raw Measurement Data PRELIMINARY VERSION
5.2.2 Light Induced Standard Deviation of the Spatial Noise
Light induced standard deviation of the spatial noise in [DN] versus light induced meanof gray values [DN] .
80
70
60
50
40
30
20
10
0
Std
. Dev
. Gra
y V
alue
(B
right
- D
ark)
[DN
]
3500300025002000150010005000
Mean Gray Value (Bright - Dark) [DN]
'acA645-100gm' (70 cameras), Spatial Gain Noise
Figure 29: Light Induced Standard Deviation of the Spatial Noise
The variance coefficient of the spatial gain noise S2g or its standard deviation
value Sg respectively, is computed according to the mathematical model as:
PRNU1288 = Sg =
√σ2
y.spat − σ2y.spat.dark
µy − µy.dark
, (17)
which describes the linear correspondence in figure 29. Match a line through theorigin to the linear part of the data. The line’s slope equals the standard deviation valueof the spatial gain noise Sg .
40 Basler acA645-100gm
PRELIMINARY VERSION REFERENCES
References
[1] EUROPEAN MACHINE VISION ASSOCIATION (EMVA): EMVA Standard 1288 - Stan-dard for Characterization and Presentation of Specification Data for Image Sensorsand Cameras (Release A1.03). 2006
Basler acA645-100gm 41