Image Display Issue...

CCD cameras (CMOS/CCD), DSLRs, telescope mounts, focusers, autoguiders, domes, Roll off roofs, etc..
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stellar.skies
Posts: 11
Joined: Tue Feb 20, 2018 10:41 pm

Mon Mar 05, 2018 6:43 pm

Just moving this over from the Direct Focus Thread...

Cyril,

I will also say that my captures made in PRISM look much worse than they do in other programs. I can't understand why my ZWO ASI1600MM-C and QHY163M images look so noisy and grainy in Prism vs. Sequence Generator Pro for example. See the attached screenshot comparing a 9 sec flat dark and how it is displayed in Prism vs. Sequence Generator Pro. Is there something wrong with how Prism interprets data from these cameras?

PrismBadImagePreview.png
keving
Posts: 53
Joined: Thu Dec 14, 2017 4:49 am

Tue Mar 06, 2018 3:22 am

[From other thread too]

Yes - I have seee this too...looks like rendering is in 8-bit while underlying data is possibly much more finely resolved. Would be nice to be able to render all the way up to 24 bit..

thanks

Kevin
Hamza Touhami
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Tue Mar 06, 2018 9:28 am

Gents

Let me ask the obvious here, have you adjusted your display cutoffs under Software Settings > Image display > Stellar Image type?
Hamza Touhami | Site Administrator
Hyperion-Astronomy.com
keving
Posts: 53
Joined: Thu Dec 14, 2017 4:49 am

Tue Mar 06, 2018 10:58 am

Hi there

No - I hadn't and that is a handy tip.. I now have a more sensible histogram as default for 'stellar image'

However, I think the problem is still there ...
The image I am considering is a 32-bit float, (I had erroneously selected 'save as 16-bit' for the first couple of sessions, but that is now fixed)
But in the image view, there are only 256 grey levels available (as you move the mouse over the image and read out at the bottom)
This gives it a grainy effect and faint things are lost in the noise. In Pixinsight I get a better rendering of the 32 bit floating scale and can see things more clearly.
I attach screen shots in both packages to compare (obviously something is lost here but I think its still apparent). Its also single short exposure sub, but it works to make the point I think...

First Pixinsight...
CapturePI.JPG
Now Prism (where I have tried to roughly match the stretch)
CapturePrism.JPG

Kevin
clupus
Posts: 29
Joined: Mon Jan 22, 2018 1:48 pm

Wed Mar 07, 2018 2:23 pm

Interesting!

I also was wondering why my images showed a lot of noise and being a newbie couldn't understand why. I've gone to "Image Display" and into "Stellar Image Type" as suggested. What would reasonable settings be? Currently the numbers are 95 and 5.

Hank
Hamza Touhami
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Wed Mar 07, 2018 2:34 pm

I use 0.10 for the low and 99.5 for the high cut, works exceptionally well with bright targets.
Hamza Touhami | Site Administrator
Hyperion-Astronomy.com
keving
Posts: 53
Joined: Thu Dec 14, 2017 4:49 am

Thu May 10, 2018 5:47 am

I think this one is still unresolved...

It is simply that, when displayed, images only seem to have 256 grey levels. They clearlry have more availiable as witnessed in the screen grabs in my ealrlier post from Pixinsight..
is there is a setting for increasing the screen resultion to at least 16bit?
jason
Posts: 44
Joined: Thu Apr 18, 2019 3:53 am

Thu May 02, 2019 3:42 am

@Hamza Touhami

I seem to be having this same issue as OP's opening image. I get it on my asi 183mm pro (mono) and my qhy 294c (color).

This really does seem to be bit-depth related issue. Sharpcap displays with the same settings perfectly in both ascom and native drivers.

I've spent many hours trying to get prism to work with it.

Ticking under ccd the grab as 16bit's does not seem to fix the issue either although it alters the image.
Hamza Touhami
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Mon May 06, 2019 10:24 am

I understand, we have discussed this issue and it seems the actual display mechanism has to be reworked. I will add to the list as well. Thanks for the pointers guys/gals.
Hamza Touhami | Site Administrator
Hyperion-Astronomy.com
keving
Posts: 53
Joined: Thu Dec 14, 2017 4:49 am

Mon Jul 29, 2019 6:03 am

I think it would be useful to have (at least) 16bit resolution here. However, I have discovered that the 64-bit version of Prism does indeed display at higher res. So, given the 32 bit version is nominally directed at 'field work' (attaching kit etc) then maybe its not as big a problem as I first thought.

Kevin
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