Re: [MaxImDL] RE: Remove Bad Pixels - Too many bad pixels error?


Nov 1, 2013

 


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#54996 Nov 1, 2013

I am generating bad pixel maps for my cameras, and am encountering a strange error.

I have a ST2000XM and a STF8300M. For both cameras I generate Master Darks (Sigma clip 15 images) at 1 minute and 10 minutes, at bin 1x1 and 2x2. I then use those Master Darks to generate the Bad Pixel Map, using Autogenerate in the Remove Bad Pixels dialog. I use something like 2000-3000 in the Hot Pixel threshold setting.

The results:ST2000XM���� ���� 1 min�� 1x1���������������������� Works fineST2000XM������ 10 min�� 1x1���������������������� Works fineST2000XM���� ���� 1 min�� 2x2 �������������������� Works fineST2000XM������ 10 min�� 2x2 �������������������� Works fine

STF8300M�� �� �� 1 min�� 1x1���������������������� Works fineSTF8300M�� �� 10 min�� 1x1���������������������� Works fineSTF8300M�� �� �� 1 min�� 2x2 �������������������� Fails!STF8300M�� �� 10 min�� 2x2 �������������������� Fails!

When the Remove Bad Pixels process fails, it gives an error popup indicating "There are too many bad pixels in this image". I have tried a variety of Hot Pixel threshold settings; even at 50000 it gets the error. The darks are typical looking darks; there clearly are not huge numbers of 50000 hot pixels! Mostly they are around 1000-3000. The typical salt and pepper look to the darks; no unusual number of hot pixels. The STF8300 is about 2 weeks old, the ST2000XM about 10 years.

So, I am confused. The STF8300 1x1 bin images work fine; I might think there would be even more hot pixels there. The ST2000XM works fine with both 1x1 and 2x2 bins.

I will try and post a sample Master Dark in the Files section under folder BrewBadPixelMap.



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#54997 Nov 1, 2013

Hi,

have a look at the statistics. For me it seems as if you have a miss understanding of bad pixels. Take a 10 Min dark image and calibrate it. Then have a look at the result. If you have hot pixels still there than that are bad pixels. I think you will not find one.

Konstantin



Konstantin v. Poschinger

Hammerichstr. 522605 Hamburg040/88057470171 1983476

Am 01.11.2013 um 22:05 schrieb eridanibrew@...> eridanibrew@...>:

��I am generating bad pixel maps for my cameras, and am encountering a strange error.

I have a ST2000XM and a STF8300M. For both cameras I generate Master Darks (Sigma clip 15 images) at 1 minute and 10 minutes, at bin 1x1 and 2x2. I then use those Master Darks to generate the Bad Pixel Map, using Autogenerate in the Remove Bad Pixels dialog. I use something like 2000-3000 in the Hot Pixel threshold setting.

The results:ST2000XM���� ���� 1 min�� 1x1���������������������� Works fineST2000XM������ 10 min�� 1x1���������������������� Works fineST2000XM���� ���� 1 min�� 2x2 �������������������� Works fineST2000XM������ 10 min�� 2x2 �������������������� Works fine

STF8300M�� �� �� 1 min�� 1x1���������������������� Works fineSTF8300M�� �� 10 min�� 1x1���������������������� Works fineSTF8300M�� �� �� 1 min�� 2x2 �������������������� Fails!STF8300M�� �� 10 min�� 2x2 �������������������� Fails!

When the Remove Bad Pixels process fails, it gives an error popup indicating "There are too many bad pixels in this image". I have tried a variety of Hot Pixel threshold settings; even at 50000 it gets the error. The darks are typical looking darks; there clearly are not huge numbers of 50000 hot pixels! Mostly they are around 1000-3000. The typical salt and pepper look to the darks; no unusual number of hot pixels. The STF8300 is about 2 weeks old, the ST2000XM about 10 years.

So, I am confused. The STF8300 1x1 bin images work fine; I might think there would be even more hot pixels there. The ST2000XM works fine with both 1x1 and 2x2 bins.

I will try and post a sample Master Dark in the Files section under folder BrewBadPixelMap.



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#55011 Nov 2, 2013

Konstantin: sorry, I don't understand your note. I have combined 15 10 minute dark frames to make a Master Dark.



I don't know what you mean by calibrating a dark.

I think you are saying to apply the bad pixel map to a 10 min dark to verify that the hot pixels have been removed? In the case of the failing maps this cannot be done - there is nothing in the map, the map creation failed.



I am creating Bad Pixel Maps to be used during the calibration of Light images. I use the Remove Bad Pixels dialog to create the map based on the Master Dark. The process is working fine for all of the ST2000XM Master Darks (both bin 1 and bin2), but failing for the STF8300M 2x2 binned Master Darks (works fine for bin 1). In the failing cases I get the error message "There are too many bad pixels in this image", and nothing gets added to the map's list of bad pixels. No map is created.

I added the Master Dark frame I am having fail to the file system in this group. Can you autogenerate a bad pixel map from this dark?





---In maximdl@yahoogroups.com, k.poschinger@...> wrote:

Hi,

have a look at the statistics. For me it seems as if you have a miss understanding of bad pixels. Take a 10 Min dark image and calibrate it. Then have a look at the result. If you have hot pixels still there than that are bad pixels. I think you will not find one.

Konstantin



Konstantin v. Poschinger

Hammerichstr. 522605 Hamburg040/88057470171 1983476

Am 01.11.2013 um 22:05 schrieb eridanibrew@...> eridanibrew@...>:

��I am generating bad pixel maps for my cameras, and am encountering a strange error.

I have a ST2000XM and a STF8300M. For both cameras I generate Master Darks (Sigma clip 15 images) at 1 minute and 10 minutes, at bin 1x1 and 2x2. I then use those Master Darks to generate the Bad Pixel Map, using Autogenerate in the Remove Bad Pixels dialog. I use something like 2000-3000 in the Hot Pixel threshold setting.

The results:ST2000XM���� ���� 1 min�� 1x1���������������������� Works fineST2000XM������ 10 min�� 1x1���������������������� Works fineST2000XM���� ���� 1 min�� 2x2 �������������������� Works fineST2000XM������ 10 min�� 2x2 �������������������� Works fine

STF8300M�� �� �� 1 min�� 1x1���������������������� Works fineSTF8300M�� �� 10 min�� 1x1���������������������� Works fineSTF8300M�� �� �� 1 min�� 2x2 �������������������� Fails!STF8300M�� �� 10 min�� 2x2 �������������������� Fails!

When the Remove Bad Pixels process fails, it gives an error popup indicating "There are too many bad pixels in this image". I have tried a variety of Hot Pixel threshold settings; even at 50000 it gets the error. The darks are typical looking darks; there clearly are not huge numbers of 50000 hot pixels! Mostly they are around 1000-3000. The typical salt and pepper look to the darks; no unusual number of hot pixels. The STF8300 is about 2 weeks old, the ST2000XM about 10 years.

So, I am confused. The STF8300 1x1 bin images work fine; I might think there would be even more hot pixels there. The ST2000XM works fine with both 1x1 and 2x2 bins.

I will try and post a sample Master Dark in the Files section under folder BrewBadPixelMap.







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#55015 Nov 3, 2013

Hi Robert,

I think that is your name.��I have taken a look at your Master_Dark file. It seems to me, that you have generated a bad pixel map without a bias calibration. In a image with a so short exposure time most of the information is coming from the readout noise. The rest is so little that when you would build up a baad pixel map, all will be classified as bad. So don't even bother with the bad pixel map. I found that if your camera is a good one, use the bad pixel map only if you have bad columns.��

Konstantin��



Konstantin v. Poschinger

Hammerichstr. 522605 Hamburg040/88057470171 1983476

Am 03.11.2013 um 02:50 schrieb eridanibrew@...> eridanibrew@...>:

��

Konstantin: sorry, I don't understand your note. I have combined 15 10 minute dark frames to make a Master Dark.



I don't know what you mean by calibrating a dark.

I think you are saying to apply the bad pixel map to a 10 min dark to verify that the hot pixels have been removed? In the case of the failing maps this cannot be done - there is nothing in the map, the map creation failed.



I am creating Bad Pixel Maps to be used during the calibration of Light images. I use the Remove Bad Pixels dialog to create the map based on the Master Dark. The process is working fine for all of the ST2000XM Master Darks (both bin 1 and bin2), but failing for the STF8300M 2x2 binned Master Darks (works fine for bin 1). In the failing cases I get the error message "There are too many bad pixels in this image", and nothing gets added to the map's list of bad pixels. No map is created.

I added the Master Dark frame I am having fail to the file system in this group. Can you autogenerate a bad pixel map from this dark?





---In maximdl@yahoogroups.com, k.poschinger@...> wrote:

Hi,

have a look at the statistics. For me it seems as if you have a miss understanding of bad pixels. Take a 10 Min dark image and calibrate it. Then have a look at the result. If you have hot pixels still there than that are bad pixels. I think you will not find one.

Konstantin



Konstantin v. Poschinger

Hammerichstr. 522605 Hamburg040/88057470171 1983476

Am 01.11.2013 um 22:05 schrieb eridanibrew@...> eridanibrew@...>:

��I am generating bad pixel maps for my cameras, and am encountering a strange error.

I have a ST2000XM and a STF8300M. For both cameras I generate Master Darks (Sigma clip 15 images) at 1 minute and 10 minutes, at bin 1x1 and 2x2. I then use those Master Darks to generate the Bad Pixel Map, using Autogenerate in the Remove Bad Pixels dialog. I use something like 2000-3000 in the Hot Pixel threshold setting.

The results:ST2000XM���� ���� 1 min�� 1x1���������������������� Works fineST2000XM������ 10 min�� 1x1���������������������� Works fineST2000XM���� ���� 1 min�� 2x2 �������������������� Works fineST2000XM������ 10 min�� 2x2 �������������������� Works fine

STF8300M�� �� �� 1 min�� 1x1���������������������� Works fineSTF8300M�� �� 10 min�� 1x1���������������������� Works fineSTF8300M�� �� �� 1 min�� 2x2 �������������������� Fails!STF8300M�� �� 10 min�� 2x2 �������������������� Fails!

When the Remove Bad Pixels process fails, it gives an error popup indicating "There are too many bad pixels in this image". I have tried a variety of Hot Pixel threshold settings; even at 50000 it gets the error. The darks are typical looking darks; there clearly are not huge numbers of 50000 hot pixels! Mostly they are around 1000-3000. The typical salt and pepper look to the darks; no unusual number of hot pixels. The STF8300 is about 2 weeks old, the ST2000XM about 10 years.

So, I am confused. The STF8300 1x1 bin images work fine; I might think there would be even more hot pixels there. The ST2000XM works fine with both 1x1 and 2x2 bins.

I will try and post a sample Master Dark in the Files section under folder BrewBadPixelMap.



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