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display problem with stacked images

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spp's picture
display problem with stacked images

I have been having intermittent problems with displaying stacked images in VPhot.  The  stacked image display appears as all white or all black. 

I can go to one of the unstacked sub-images, look in tools>image display, then use those display setting to reset the settings in the stacked image.  These new settings will then display the stacked image normally.

I've attached a screen shot of a stacked Ic filtered image with this problem showing my saved comp sequence and the image display settings.  If I use Low = 1933 and High = 2717, this stacked image will display normally.  The FITS image is in the attached zip file.

The stacked V and B images from this image set display normally.



MZK's picture
Blank image


Please share images to me at mzk. Could you also note what software you used to collect and reduce before uploading to vphot. Anything new or different than normal? Did you stretch them differently? Bscale or bzero got messed up?


spp's picture
Blank images


Actually, they aren't blank; they are just scaled very poorly to the point where they look blank white or blank black.  The problem stacked image will display fine if I reset the Image Display parameters in the stacked image to match those in one of the unstacked images.

I shared with you the five Ic filtered images of GU Sgr from BSM_S which, when stacked, produce the problem stacked image.   The  V and B images in this set stacked normally.

I am pretty confident that all the stacking problems I have encountered came from BSM systems, and it is possible that they all came from BSM_S. 

A possible clue:   When I get BSM_S images they sometimes are listed in the Available Images window as coming from "ACP->Cel.." ( In the header the TELESCOP value is "ACP->Celestron CGEM 5.22".)  When this happens, before I do stacking (or any other operations on the images) I rename them in the "Tele" column to BSM_S. 

Thanks for looking into this.




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