Integration of stacked images.

Roger Smith

Hi Adam,

Are there any Pixinsight  processing issues via WBPP, NSG script, and integration from using pre-stacked images as the input? Diffraction Limited SBIG has several cameras with StackPro that integrates up to 16 subs then downloads it as one image. There is no alignment. 

Advantages of this are 

--Increased bit depth. With a 12 bit camera, 16 subs gives a 16 bit sub.  

--Less storage space (including processing files) required. 

Some potential issues I am thinking:Hhow best to capture dark frames? Do they also need to be with same number/time sub frames integrated in the camera? Or can one frame of the full duration of the downloaded light file work okay?

Same questions for flats.

Same questions for flat darks.

If I start with a 14 bit camera and stack 16 frames, the bit depth will be higher than 16bit.  Should the higher bit depth image be processed in any special way?

SharpCap also stacks images without alignment (optional) on your computer, and then can save the stacked image. It can save a series of stacked, uncalibrated) images for further processing outside of PI. Any PI issues with calibration with this?  If I save maybe 20 subs, the bit depth will be higher than 16 bit.

Many thanks,

    Roger

BlockHead

I think in principle there isn't an issue and no special steps need to be taken. I would assume the calibration data (the darks) would need to be taken in the same way as the lights in order to get all of the noise sources to be the same. I am aware that calibration of these data can be difficult - but I do not have access to this kind of data so I do not know the full story. 

So the real answer is, I do not know in detail.

-the Blockhead

Roger Smith

I am going to try the direction by live stacking (SharpCap) short exposures into longer exposures, then processing multiple longer exposures in PI.
I will gather calibration frames the same as the lights. Normally my flat darks are 2.3S, so I will divide them into 16x 0.143S live stacked subs, and load the stacks to WBPP.
Roger