Created flats with sharpcap and trying to stack in ASIDeepStack program.
ASI program will not stack Lights using only Flats. it seems to require Bias also.
Is this normal?
Thanks
Problem using ASIDeepStack with FLATS
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Re: Problem using ASIDeepStack with FLATS
Hi,
bias (or dark flat) frames do need to be used as part of flat frame correction to subtract away the part of the image signal that didn't come from light hitting the sensor. If you have created the flat frames using the SharpCap 'Create Flat' tool though, that subtraction has already been done before the flat frame has been saved, so there is no need (in theory) to have the bias frame when processing...
However, it sounds like ASIDeepStack isn't really expecting that - it is expecting to have separate flat and bias frames, and so won't let you proceed without both. I suppose in theory if you somehow made a perfectly black (zero pixel value throughout) frame and gave that to ASIDeepStack then it might do the right thing (subtract the zero frame from the SharpCap flat and use the result to do flat correction), but that might cause problems in other parts of the processing if the zero bias frame gets used elsewhere in places where it is not appropriate.
This sort of thing highlights my normal recommendation which is to do all of your image processing in one application (either everything in SharpCap, or everything in PixInsight or DSS or whatever). If you start mixing them up then there is always the possibility that you encounter this sort of problem where the applications do things in subtly different ways. I'm not claiming that the mixed approach can never work, it is just full of potential pitfalls...
If you captured your flat/dark files in SharpCap and ticked the option to 'keep individual frames' then you can probably feed those (there will be individual flat and bias frames) to ASIDeepStack and let it create its own master flat.
cheers,
Robin
bias (or dark flat) frames do need to be used as part of flat frame correction to subtract away the part of the image signal that didn't come from light hitting the sensor. If you have created the flat frames using the SharpCap 'Create Flat' tool though, that subtraction has already been done before the flat frame has been saved, so there is no need (in theory) to have the bias frame when processing...
However, it sounds like ASIDeepStack isn't really expecting that - it is expecting to have separate flat and bias frames, and so won't let you proceed without both. I suppose in theory if you somehow made a perfectly black (zero pixel value throughout) frame and gave that to ASIDeepStack then it might do the right thing (subtract the zero frame from the SharpCap flat and use the result to do flat correction), but that might cause problems in other parts of the processing if the zero bias frame gets used elsewhere in places where it is not appropriate.
This sort of thing highlights my normal recommendation which is to do all of your image processing in one application (either everything in SharpCap, or everything in PixInsight or DSS or whatever). If you start mixing them up then there is always the possibility that you encounter this sort of problem where the applications do things in subtly different ways. I'm not claiming that the mixed approach can never work, it is just full of potential pitfalls...
If you captured your flat/dark files in SharpCap and ticked the option to 'keep individual frames' then you can probably feed those (there will be individual flat and bias frames) to ASIDeepStack and let it create its own master flat.
cheers,
Robin
Re: Problem using ASIDeepStack with FLATS
Thanks for looking at this robin.
I missed that feature of your software
"If you captured your flat/dark files in SharpCap and ticked the option to 'keep individual frames' "
I will make a note of using it to keep all options open for processing.
Take Care
Steve
I missed that feature of your software
"If you captured your flat/dark files in SharpCap and ticked the option to 'keep individual frames' "
I will make a note of using it to keep all options open for processing.
Take Care
Steve