Post on 29-Oct-2019
23.09.2002 Image Engineering Dietmar Wueller 1
Pro and contra using ISO 12233
for resolution measurement
23.09.2002 Image Engineering Dietmar Wueller 2
SFR Measurement
23.09.2002 Image Engineering Dietmar Wueller 3
SFR Measurement
Figure 4 — Flow-chart of SFR measurement algorithm
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SFR Measurement
SFR Measurement has proven
• Reliability.• High accuracy.
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SFR Measurement
SFR of Leica S1 Pro
0,00
0,20
0,40
0,60
0,80
1,00
0 1000 2000 3000 4000 5000
Frequency [LW/PH]
Sp
atia
l Fre
qu
ency
Res
po
nse
SFRhorizontalSFRvertikal
Mittelwert
Aliasing Region
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SFR Measurement
But problems appear if the camera applies:
• Sharpening.• Aliasing artifacts.• Artifacts caused by JPEG
compression.
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SFR Measurement
SFR Olympus Camedia C-1400XL
0,00
0,20
0,40
0,60
0,80
1,00
1,20
1,40
1,60
0 200 400 600 800 1000
Frequency [LW/PH]
Sp
atia
l Fre
qu
ency
Res
po
nse
SFRhorizontal
SFRvertikal
Mittelwert
Aliasing Region
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SFR Measurement
Consequence:
• The SFR does give the correct edge analysis!
• But the result does not tell anything about the ability of the camera to capture fine detail.
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Visual analysis from ISO 12233 chart
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Visual analysis from ISO 12233 chart
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Visual analysis from ISO 12233 chart
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Kontrast analysis from ISO 12233 chart
0
50
100
150
200
250
100 200 300 400 500 600 700 800 900 1000
Frequency [LW/PH]
Dig
ital
Val
ues
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Contrast analysis from ISO 12233 chart
0,00
10,00
20,00
30,00
40,00
50,00
60,00
70,00
80,00
90,00
100,00
100 200 300 400 500 600 700
Frequency [LW/PH]
Co
ntra
st [
%]
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Problem:
• Where to draw the line for a limiting resolution?!
Contrast analysis from ISO 12233 chart
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Visual analysis from ISO 12233 chart
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Visual analysis from ISO 12233 chart
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Problem:
• Where to draw the line for a limiting resolution?!
Visual analysis from ISO 12233 chart
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Visual analysis from a special chart
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Problem:
• Where to draw the line for a „limiting resolution“?!
• no differentiation between center and edges.
Visual analysis from a special chart
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Visual analysis from a special chart
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Using Siemens stars
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Conclusions
• SRF analysis is the preferred method if we have access to „raw“ data.
• If we do not have raw data a visual analysis consists of a low accuracy.
• A more reliable „calculation“-method is needed for consumer cameras.
• Such a method can be based on Siemens stars.