Measure OTF of the lens-sensor system - Revision history

Andrey.filippov at 18:33, 20 November 2017

2017-11-20T18:33:08Z

← Older revision		Revision as of 18:33, 20 November 2017
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			{{Legacy}} See more about lens measurements on Elphel Blog: [https://blog.elphel.com/category/calibration/ Category:calibration]

	==Software==		==Software==
	* Install [http://rsbweb.nih.gov/ij/ ImageJ].		* Install [http://rsbweb.nih.gov/ij/ ImageJ].

Oleg at 04:49, 18 June 2010

2010-06-18T04:49:59Z

← Older revision		Revision as of 04:49, 18 June 2010
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	* The minimum is 3 stripes: BWB or WBW.		* The minimum is 3 stripes: BWB or WBW.
	{\|		{\|
	\|[[Image:Slanted edges pattern.jpeg\|thumb\|~~300px~~\|Test Pattern]]		\|[[Image:Slanted edges pattern.jpeg\|thumb\|400px\|Test Pattern]]
	\|}		\|}

Oleg at 03:53, 18 June 2010

2010-06-18T03:53:07Z

← Older revision		Revision as of 03:53, 18 June 2010
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	'''<font size=5>3.</font>''' Select the area of the measurement.		'''<font size=5>3.</font>''' Select the area of the measurement.
	Note:		Note:
	Should contain at least 2 edges - 1x Black-to-White & 1x White-to-Black but '''the more edges in the area of interest the better'''		Should contain at least 2 edges - 1x Black-to-White & 1x White-to-Black but '''<font size=3>the more edges in the area of interest the better</font>'''
	{\|		{\|
	\|[[Image:Slanted edges pattern select area.jpeg\|thumb\|300px\|Selection]]		\|[[Image:Slanted edges pattern select area.jpeg\|thumb\|300px\|Selection]]

Oleg at 03:48, 18 June 2010

2010-06-18T03:48:37Z

← Older revision		Revision as of 03:48, 18 June 2010
Line 61:		Line 61:
	'''<font size=5>3.</font>''' Select the area of the measurement.		'''<font size=5>3.</font>''' Select the area of the measurement.
	Note:		Note:
	Should contain at least 2 edges - 1x Black-to-White & 1x White-to-Black		Should contain at least 2 edges - 1x Black-to-White & 1x White-to-Black but '''the more edges in the area of interest the better'''
	{\|		{\|
	\|[[Image:Slanted edges pattern select area.jpeg\|thumb\|300px\|Selection]]		\|[[Image:Slanted edges pattern select area.jpeg\|thumb\|300px\|Selection]]

Oleg at 00:55, 18 June 2010

2010-06-18T00:55:21Z

New page

==Software==
* Install [http://rsbweb.nih.gov/ij/ ImageJ].
* Get '''MTF_Bayer.java''' plugin from [http://elphel.git.sourceforge.net/git/gitweb.cgi?p=elphel/ImageJ-Elphel;a=tree GIT] and compile it in ImageJ.
Note:
1.1. Copy the source to the "Plugins" folder of the ImageJ installation
1.2 Launch ImageJ
1.3 Drop down menu "Plugins -> Compile and Run..."

2.1 It might be useful getting the following plugins as well:
'''JP46_Reader.java''' - converts JP46
'''Crosstalk_Deconv.java''' - can generate simulation pattern

==Test Pattern==
Print the test pattern (A) or generate it (B).

===A - print===
* The stripes on the paper are vertical of course. But there should be a small angle on the test image.
* Each stripe width on the test image should be not less than 32 pixels
* The minimum is 3 stripes: BWB or WBW.
{|
|[[Image:Slanted edges pattern.jpeg|thumb|300px|Test Pattern]]
|}

===B - generate===
* Get '''Crosstalk_Deconv.java''' - compile and run

* Click '''Create Color Pattern'''
* Choose ''Pattern Type''
* Set ''Nonlinearity'' to 1 (square)
* Set the stripes period (each stripe width on the test image should be not less than 32 pixels)
* '''OK''' - the plugin generates only RED, GREEN or BLUE stripes - so it will be like color filter. RED will be ok.

==Camera Settings==
{| border=1
| Gamma
| 1.0
|-
| Black Level
| 0.0
|-
| Color Saturation
| 0.0
|-
| Image Quality
| 100%
|-
| Color Sensor Mode
| Mono
|}

Note:
Set the Color Sensor Mode to Mono only when Color Saturation is 0.0

==ImageJ==
'''1.''' Save the image of the test pattern.

'''2.''' Launch ImageJ - open the saved image and launch the plugin
{|
|[[Image:Plugin interface.jpeg|thumb|600px|MTF Bayer plugin interface]]
|}
'''3.''' Select the area of the measurement.
Note:
Should contain at least 2 edges - 1x Black-to-White & 1x White-to-Black
{|
|[[Image:Slanted edges pattern select area.jpeg|thumb|300px|Selection]]
|}

'''4.''' '''Process''' - the MTF chart will be shown
Note:
Change the image type in ImageJ to 32-bit if you are getting an error: drop-down menu Image -> Type
{|
|[[Image:MTF chart example.jpeg|thumb|500px|Result chart: the MTF curves are drawn for all 4 color channels for BW and WB edge (8 as a result):
RED - red curve, GREEN (from RGR line) - light blue curve, GREEN (from GBG line) - green curve, BLUE - blue curve]]
|}

'''5.''' '''Show MTF text''' for spreadsheet use.

==Results==
* The higher curve the better.
* Normally the blue channel has the worst curve.