I have been using KStars/Ekos/Indi to operate my AP equipment for around 18 months. I presently run the Astroberry Server compilation of KStars/Ekos/Indi on two RPi4s. I have noted and enjoyed the many incremental improvements made to the software over that time, and I am conscious of the excellent work done by a number of contributors to these developments.
The FITS viewer is one feature of the KStars package that still shows some peculiarities in behaviour (from my user perspective). Captured images are displayed with automatic stretch which is often a good starting point. But there are three sliders to influence the stretch curve for shadows, mid tones and highlights. These controls seem to have an effect on the image only when being moved left or right, but the image stretch returns back to the original auto-stretch when the sliders are no longer in movement. The auto-stretch wizard control button is sometimes present and sometimes not. When I move the sliders I often get an increase in image contrast that lets me see my target more clearly, and I wonder if the auto-stretch function has some adjustments options that I am not aware of?
I am conscious that FITS Viewer does not carry out debayering in the limited resources mode with the RPi4, and so I tend to use it as a quick check of the image before I transfer it to my laptop for fuller examination.
Am I missing something in the way I use the FITS Viewer?

I have just run up my system indoors, as you do when it’s raining, and switched on debayering in the FITS Viewer options. This is transformational - the controls now all work as you would expect and the auto-stretched full colour images from the last capture session on the 26/12 are great without tweaking. I understand that the debayering option is off by default when you have a ‘resource limited’ processing system. So is the RPi4 4GB running astroberry from a SanDisk Extreme 500GB SSD a resource limited system? Am I likely to suffer some adverse consequences if I run in debayering mode from now on?

And are the dynamic effects of control slider adjustments just a bug/feature when debayering is switched off?

Hi I always use in active debayer mode and I have not rediscovered problems, I have your own equipment pi4 4gb and ed80pro! My curiosity is you transfer to FIT or leave in RAW? if I transfer to fit I can not understand if the conversion leaves the dynamic intact, doing tests in the house if I put 1sec of laying or 5 sec the fit view always shows an undefined image and does not seem to increase the brightness even if I exposeif I transfer to fit I can not understand if the conversion leaves the dynamic intact, doing tests in the house if I put 1sec of laying or 5 sec the fit view always shows an undefined image and does not seem to increase the brightness even if I exhibit 5 sec

Firstly thanks for your reassurance about the active debayering. Until now I presumed there would be a big performance hit if I used it. I shall leave it set from now on.
On RAW versus FITS, I believe that FITS adds a lot of metadata to the file header (focal length of telescope, geographic location etc.) but does not process the RAW image data itself which stays in linear form. So I wouldn’t expect any difference in display or stacking performance.

Ed,

Let me know if you still think there's a bug in the fitsviewer stretching, and if so, please post somewhere an image I can download and read into a fitsviewer, and instructions on what I should do to replicate the problem.

Sorry if things aren't clear. Here's how I intended it:


The button on the far left turns on and off stretching. If you have it off, the image is displayed linear, as captured.
All the other buttons are then disabled until you turn it back on.

The button on the far right (magic wand) sets the image back onto the default stretch setting.
If the image is already on the default stretch setting (as it is initially), the button is disabled, as it would do nothing.

The sliders in the middle control the shadow, midtone and clipping parameters.
You can move them, left or right, and as you move them, a real-time (but low resolution, for compute reasons) preview of the stretch is shown.
When you let go of the slider, the setting is kept, but the button returns to the middle of its range so that you can make further adjustments--there is very little screen space.
You can tell the setting is kept as the number shown should not change after you release the button. Think of these as "relative" sliders.
Also, when you let go of the slider, you also get the full-resolution image, instead of the real-time approximation.
Further, now that you've changed a parameter, the magic wand activates, allowing you to return to the default stretch.

Stretching should work on a monochrome or RGB image. If an RGB image is not debayered, it is treated as monochrome (and you can see the bayer pattern if you zoom in).

The stretch scheme, and defaults used, is what's described in the PixInsight documentation:
See section 8.5.6 of pixinsight.com/doc/docs/XISF-1.0-spec/XISF-1.0-spec.html
though without the "expansions" described there.

Hy

PS I would think an RPI4 could auto-debayer just fine, though I don't have an RGB astro camera.
If you are auto-computing HFR, though, you should consider the "quick HFR" option.

Very good information. It is possible to ultimately have 2 screenshots of the FITS VIEW and EKOS parameters to use for CANON DSLR so we go safe!

Hello Hy,
Thanks for your response and may I say I have nothing but admiration for you and the other developers hard work and continuing energy. Thank you all so much!
I have retraced my steps and I am pretty sure that the present behaviour in non-debayered mode is actually different from how I recalled. The changes have probably been made since 3.5.0 - I did notice that the spelling of 'hightlights' has been corrected and I guess this was at the same time as other changes. However my switching on of Debayering has made a big difference, and I am keen for the next clear sky session to try it out in practice.
I have run up FITS Viewer on one of my recent captures and attach four screenshot files as follows:
01 - Debayering ON - the displayed image with auto-stretch and no further adjustment.
02 - Debayering OFF - the displayed image with auto-stretch and no further adjustment.
03 - Debayering OFF - I have clicked on the highlights slider and adjusted it down from 1.0 continuing to hold the mouse button. The nebulosity is certainly more visible.
04 - Debayering OFF - after the mouse button is released. The brightness increases and the nebulosity is less evident.
You can see from the images why I am delighted to find that Debayering should not cause any important performance reduction in a capture session....
Ed
PS if you would like my FITS file I'd be happy to send you a link, but my guess is any FITS file would behave in a similar fashion.

Please do send me a link to the fits--either on this thread or message me.
Hy

As mentioned, a link to the FITS file:
drive.google.com/file/d/1_RoRym9A6Flq-2R...5sN/view?usp=sharing

@Hy for those of us that use large workstations on the client end, how much extra compute would it be to do the full rendering with the sliders? I am wondering about a configuration option that would allow real-time changes from the sliders. This option is not a big enough difference to spend time on if the option would not be easy to implement though.

Jim

Ed: I couldn't access the file. I sent you a google-drive request.

Jim: This was an easy change and I had a spare hour.
I sent it on to Jasem.
See invent.kde.org/education/kstars/-/merge_requests/182
Bottom line, if/once this is submitted, you would
use the "Stretch Preview" control, (see it in the upper right below)
If you set it to 1, then the preview is full resolution. There a mouse-over tooltip if you forget.

Not sure why you couldn't download the file from my google-drive. Conversely I can't see any request in google-drive either! Here is an alternative cloud download option. www.mycloud.ch/s/S0072C7C7B44609820F4373D18955FB58DF337FCB59
Hope this works better! Ed