PixInsight Forum (historical)
Software Development => New Scripts and Modules => Topic started by: Carlos Milovic on 2011 July 19 20:41:47
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This process takes a master bias frames, and makes operation between pixels to emulate a master bias of several hundred of frames. Differences between the super bias and the master bias of a huge set is well below 1ADU acording our tests.
The idea behind this was born by some experiments conducted by Vicent Peris. He wandered what could be the result of a insanely huge amount of individual bias frames integrated. He used some 2000 images and found that for his ccd camera, vertical variations inter pixel were only noticeable at large scales. Locally, only column patters were visible. I repeated the experiment with some 400 bias with a Canon 300D (CMOS sensor) and the same was found. So, we deviced an algorithm that takes a master bias of a smaller set, and tried to reproduce the behaviour of those huge data sets.
I'll give an example of this process tomorrow.
Downloads:
Windows 64bits: http://pteam.pixinsight.com/pcldev/carlos/x64/SuperBias-pxm.dll
Linux 64bits: http://pteam.pixinsight.com/pcldev/carlos/x64/SuperBias-pxm.so
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That sounds interesting but I'm a little concerned about messing with master bias files. If I don't like the quality of my master bias I can take more of them, right? It seems that fixed patterns in bias frames depends heavily on both the sensor and the circuitry used.
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Yeah, you can always take more subs. The deal here, is that with 20 or 40, you'll end with a result that will look (and have an maximum error below 1 ADU) almost the same as a 400 or 2000 subs master bias. It is a lot that you are saving there (disk space and time).
The real issue is the question if such improvement really makes any difference to the final images... In any case, since the SuperBias procedure is almost instant, I'm always using it. My latest 10 images used them.
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Hi Carlos
Not sure how to proceed after downloading the file. Presumably I have to move it to the appropriate folder. Help appreciated.
Geoff
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Hi Geoff, save the file in bin folder and from PI install it
Process>Modules>Install Modules>Search
But!, I think that this module do not works in 1.8RC3 yet.
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Thanks Alejandro
That works for me in 1.7. I haven't installed 1.8 yet.
Geoff
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Are there any physical considerations that are behind the process? It is difficult for me to understand that it is possible to generate a high quality masterBias from just a few biases? Sound like mathematical voodoo ;)...
Georg
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Just curious. What determines when a module and/or script is released with PI versus having to download it manually?
Craig
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Just curious. What determines when a module and/or script is released with PI versus having to download it manually?
mmmh, it is not easy. I have a file with last update of most of the modules and scripts and if one is not present in the oficial distribution list, then I install it. But it depends on the vertion. For example I have right now 52 modules in win7 and 42 in Linux. I am missing Carlos' modules and other than are not available for 1.8 yet.
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Hi Georg
The idea behind this is that for certain cameras, vertical patterns are dominant over differences between pixels in the same column, so we may assume that the only high frequency components that are relevant are those in the x axis. So, we just have to average each column, to achieve the mean value. Since we have hundreds of pixels in the same column, it is almost the same as averaging hundreds of frames, in a individual pixel basis. Medium and large scale components are preserved with ATW.
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Hi Craig
Basically, that depends on Juan. If he has the time to look at a code, and it is considered as a valuable contribution, it is included in the standard repository. In the case of my processes, he just have put them on the qeue list, untill he have more time to look at them. We have plans to include most of them in the standard package during the 1.8 cycle.
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Is this module still available?
I played with it on PixInsight v1.7 but found that now that I have upgraded to the latest v1.8 it will not install. I went back the original directory (shown in the first post above) to see if a new version was available. The file link now gives a "404 Not Found" error and the whole directory gives a "403 Forbidden" error.
I'd like to play with this some more. It seemed to have a lot going for it. Is there now a version of SuperBias for v1.8 and if so where can it be found?
John
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Hi Craig
Basically, that depends on Juan. If he has the time to look at a code, and it is considered as a valuable contribution, it is included in the standard repository. In the case of my processes, he just have put them on the qeue list, untill he have more time to look at them. We have plans to include most of them in the standard package during the 1.8 cycle.
This is why I write scripts and not modules. Modules can be much faster but the maintenance is too involved: you have to recompile the module for each platform for each version of PI.
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I would also like to try this module. With my DSLR, I want to minimize shutter actuation.
Regards,
Charlie
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I would like to use this module as well. Is there any reason it's not included? It doesn't appear to work with v1.8.
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Hi. Is is available for Linux.
Saludos. Alejandro
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Hi guys
SuperBias has not being yet included in the standard package. Juan was quite busy with the final 1.8 release, so there wasn't much time for modules. I hope that this will change during december/january.
The final 1.8 release includes some changes to the PCL, so I'm delaying the compilation of these development modules until the official release.
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Carlos, thanks for the update!
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Any news on this? I wanted to try it out but I see it's not downloadable anymore...
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I'm working with Juan trying to solve some compillation issues. A bit more patience, p,ease. :)
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New repository here: http://www.astrophoto.cl/Research.html
SuperBias is avalaible for Windows and Linux, 64bits only.
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Thanks Carlos, will try in the next few days!
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New repository here: http://www.astrophoto.cl/Research.html
SuperBias is avalaible for Windows and Linux, 64bits only.
Carlos,
How do I use the modules.
I have downloaded the interchannel curves and spikes modules to play with.
I put them in /pixinsight/bin folder. But I don't know how to use them from there.
Scott.T
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You have to install them. Go to: Process > Modules > Install Modules...
Then, select the folder where the .dll or .so (depending on your O.S.) files are located, and click "Search". After the new modules are found, click "Install" and they'll be added to the PI platform.
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Got it, Thank you
I will try some out now.
Question: I loaded the Windows ver for the interchannel curves, but it does not show up in my processes.
I have noticed that Alejandro uses it a lot. I think he uses Linux though.
Scott T.
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I'll try the windows module as soon as I get home. The linux one opens fine here.
BTW, it is located under the IntensityTransformation category. If you restart PI, make sure that InterChannelCurves is listed in the installed modules at startup. If not, install it again.
Regards,
Carlos
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I reinstalled it and it is there now.
Nice tool.
The thing about PI is there are so many other tools to use, than in the default installation.
I just need to get familiar with how to install them and use them.
Modules , scripts
Thanks,
Scott T
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Hi Carlos and thank you for the superbias update. I tried to see if it would follow my 1100D camera and to be honest after a 500 bias frames I gave up. But the result of using superbias from a previous 60 bias shots I can definitely see that the 2000 image will be accurate for my camera and the image of the 2000 frame master bias sure looks clean.So again thank you Carlos for this great addition to my imaging
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Any chance of compiling for OSX?
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i compiled all of carlos' modules for OSX. there is another thread here with a link to that, but i have to leave the house in a second and don't have time to search just now.
rob
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They are all here:
http://www.astrophoto.cl/Research.html
The OSX version of SuperBias is here: http://www.astrophoto.cl/dev/SuperBias-pxm.dylib
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Thanks!
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Hello Carlos,
Thanks for the neat module.
I tried to apply it the master bias of by Canon 1000D camera.
I took 84 bias frames, debayered and integrated them. An STF showed a color image. But the SuperBias frame is Monochrome.
Is it the expected result? Or should I separate the channels and then apply SuperBias?
Thanks and Regards,
Keerthi
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You should not debayer raw frames for calibration. Only light frameas are debayered, after calibration, before registration and integration.
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Thanks Carlos... That makes sense.
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Carlos,
Really like this SuperBias. I tried it on 50 bias frames from a Canon 1100D at ISO 400. The original master bias has significant vertical banding. What is interesting is I tried running SuperBias and changed the Data Extraction Parameters. I ran one at default or "7", then one at "5", then one at "9". Obviously the results differ, notably in the signal information at the top of the image (it looked like amp glow in the original). What is the significance of these numbers? What might I want to see in the finished SuperBias image? Thanks.