23.09.2002 Image Engineering Dietmar Wueller 1

Pro and contra using ISO 12233

for resolution measurement

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SFR Measurement

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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

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1,00

1,20

1,40

1,60

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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

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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

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50,00

60,00

70,00

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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.