live stack image vs saved as seen

Discussions of Electronically Assisted Astronomy using the Live Stacking feature.
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edgar619
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Joined: Sat Jan 13, 2018 4:43 am

live stack image vs saved as seen

#1

Post by edgar619 »

Robin

I am a 3.2 pro license using an ASI 290MM. Recently i began using an Orion ST 80 to image nebula. For reasons i can not determine all my mono nebula images

1] the nebulosity that is quite clear, reasonably bright and detailed in the live stacking image either does NOT appear or is extremely faint in the "saved as seen image" in my SC capture folder.

2] really all the nebula that I have " saved as seen" have been MUCH MUCH MUCH darker...to the point that it is even difficult to make them brighter post processing and have faint nebulosity appear

3] those that i have "saved as adjusted" end up as a Fits file and blown out

4] although not exact , I have never had this wide a variance between live stack and saved captured images when imaging galaxies

what settings could be off? i have gain set usually to 350 although at times it needs to be higher... 400 or above....exposure can range from 10s to 30 s, brightness is set to 1, I have had to occasionally use 2x binning and digital gain 2x-8x...Is it possible filters are causing the problem? is it the default photo SW on Window 10 that is a problem?

I see PIPP is a recommended post process solution path for bringing out the color in color images taken by a 224....before i try it for mono wanted to get your input

i am experienced enough that i should have been able to identify the root cause myself ...so far can't do it

Thanks

Bruce
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Re: live stack image vs saved as seen

#2

Post by admin »

Hi,

The 2 options for the live stack save that I think you are referring to are

1) save with adjustments
2) save exactly as seen

The 2nd should save the image in PNG format exactly as you see it on the screen. This will include any adjustments you have made in the live stacking histogram section, the live stacking colour balance and the display histogram control on the right hand side.

The 'save with adjustments' option will give a result that does not include the settings of the display histogram control on the right hand side, but does include the adjustments found within the live stacking panel.

I suspect that you have set a display stretch in the right-hand panel that is brightening the image on screen and then the use of the 'save with adjustments' option will give you the darker image files during experiencing because it does not include that display stretch adjustment. Your options here are to either use the 'save exactly as seen' option or to remove the display stretch adjustment in the control of the right hand side and then use a stronger histogram stretch in the live stacking panel.

Hope this helps, Robin
edgar619
Posts: 30
Joined: Sat Jan 13, 2018 4:43 am

Re: live stack image vs saved as seen

#3

Post by edgar619 »

Robin

i will double check these settings of the two options to insure i am in sync with your explanation. I may be having a brain skip as to what happens when i make adjustments with these two histograms and what happens when i then save with either of these two options. I need another viewing session to confirm "why" and solve this

Thx

Bruce
eugenrau
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Joined: Sun Jul 30, 2023 7:21 pm

Re: live stack image vs saved as seen

#4

Post by eugenrau »

Hello,
My setup: Dob Bresser 10",Eq Platform Asterion, ZwoAsi294MC, Baader Ir-Uv Cut CMos, Sharpcap Pro
I saved live stacked frames, in every kind of "save" because I am beginner, and wasn't sure wich how works. Most of them 'save with adjustments' and 'save exactly as seen'.But at my dispair finally no one could be seen, most were black. Only one showed a skinny Andromeda mono coloured (with a part of a slanted corner inside. Could be sensor shape ?) Thought picture were Tiff so searched for Jpeg converter but sombebody told me that they are PNG's and could be seen with most computer softwares.
From Sharpcap Manual I understood that on that "save exactly as seen" in the mini/stretch histogram the pic is saved: "The bottom, save, button will save the current image exactly as seen onscreen as a PNG file. Unlike the normal SharpCap image saving functionality, this saved file *will* include the effects of any display stretch currently in effect. Note that the saved image file will have a bit depth of 8 bits regardless of the bit depth setting of the current camera.
Any changes made in the Display Histogram Stretch section only affect how the images are displayed on screen – there will not be any cha nges made to the images saved to capture fil es ( except those saved using the ‘ Save Exactly as Seen ’ button in the display histogram stretch control ."

Everybody on Discord/Dobsonian Powera repeated over and over :
* Save only with left side button, (not saying a word about for what is designed the other button, as long as most of the functions are doubled).
After reading the manual (... hope nobody will get angry or offended) and ponder, I concluded, at least <as for beginners> :
- To avoid unwanted surprises wich got one angry, avoid at all price to touch mini histogram buttons.Not bad, also not use "Save exactly as seen button".
- Improve the image by making all needed fine adjustments on main histogram and "Save with adjustments"
I was awake, not drunk, saw on screen wonderful full coloured pictures of :C20, Moon, Andromeda, M42,M43,Pleiades,Betelgeuse, Veil nebula, so had no patience to wait; I expected to be saved "with adjustments" or "exactly as seen". At least some of them, but where in Universe are they ?
eugenrau
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Re: live stack image vs saved as seen

#5

Post by eugenrau »

I am extremely angry and on the verge of dispair.I am forced to ask for anybody/everybody help and advices.
Out of a single good coloured image of a New Moon, cannot succeed to have ANY coloured pictures of many DSO I've seen.Even last time I tried 2-nd time and saved live stacked frames using both "save with adjustments" and "save as seen" buttons (situated in the left side near main histogram of live stacking).So out of monocoloured frames with stars, and a poor Andromeda, nothing else, no coloured pictures.I managed to obtain them working at colours, tens of minutes pixel by pixel. Only monocoloured skinny Andromeda and frames with stars (also monocoloured)
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Re: live stack image vs saved as seen

#6

Post by admin »

Hi,

When you save raw images from a colour camera, they appear monochrome with a grid pattern appearing if you zoom into the pixel level. To see colour in those you need to view them using a tool that can debayer the images to recover the colour info (see viewtopic.php?t=254 for more info on this).

When you have used 'save exactly as seen' from live stacking, you should get a PNG file with colour in it, matching what you see on screen. The same applies to the small save button on the mini histogram on the right. If those files are appearing to be monochrome, but the view on screen is colour, please share one with us so we can advise further.

Save with adjustments from live stacking should also give you a PNG image in colour. The other two options (16, 32 bit save) will save as FITS format - these will be colour files but some FITS viewing software like FITSLiberator does not support showing colour, so will show monochrome.

In any case, we need to see some of the saved files to understand what is going on.

cheers,

Robin
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