Live Stack with Flat Frame Bug?

A place to report problems and bugs in SharpCap
Forum rules
Please read about Troubleshooting USB Issues before posting.

*** Please do not post license keys - please report any problems with licensing to 'admin' by PM ***

Please include the following details in any bug report:

* Version of SharpCap
* Camera and other hardware being user
* Operating system version
* Contents of the SharpCap log after the problem has occurred.
[If SharpCap crashes, please send the bug report when prompted instead of including the log]
donboy
Posts: 114
Joined: Sat Mar 25, 2017 1:57 am

Re: Live Stack with Flat Frame Bug?

Post by donboy » Mon Feb 04, 2019 5:41 pm

An update to this issue:

I am getting better flat correction with the ASI294 using mono-bias with image controls set to Red 50 & Blue 50, zero for brightness/offset and exposure around 1/4 sec, and gain adjusted for exposure between 120>300. When capturing images I balance the color as best I can first in Image Controls for the specific exposure settings and calibration frames. Unfortunately ZWO still has not provided drivers that allow light pollution filters to AWB using the Red and Blue settings in Image Controls; the red channel is always set to max and still is not enough. I use Idas LPS D1 and also Idas LPS P2 filters, which are noted to be some of the most neutral LPS filters.

Additionally there is less of an issue and flats appear better when there is less vignetting which generally occurs when I use my scopes in native format without focal reducers.

Don

poolemarkw
Posts: 54
Joined: Mon Mar 26, 2018 5:49 pm
Location: Indialanatic, FL

Re: Live Stack with Flat Frame Bug?

Post by poolemarkw » Tue Mar 12, 2019 1:10 am

Robin and BlackWikkett,

I'm having these exact same frustrating issues with my ZWO ASI294MC Pro camera for Live Stacking and using an Optolong L-Pro filter. Is there any update? I've just read through the entire thread and here's what I surmise so far. I have question marks where I'm certain what to do, and I certainly could have eliminated critical steps. It would be SO helpful if we can end up with a very detailed set of instructions as shown below

1) Lights Set Up
1.1) Determine the desired Gain, Exposure, and Brightness for the intended target.
1.2) Use the HIstogram tool and the White Balance sliders for Red and Blue to align the peaks or use Auto??

2) Create Darks (does it matter if the Optolong filter is in place?)
2.1) Exact same settings for Gain as the LIghts setup
2.2) Exact same settings for Exposure as the lights setup
2.3) Exact same settings for Brightness as the Lights setup
2.4) White Balance Red set to ??? (Auto, same as LIghts, or doesn't matter?)
2.5) White Balance Blue set to ??? (Auto, same as Lights, or doesn't matter)

3) Create Flats (Optolong Filter MUST be in place?)
3.1) Make sure there is NOTHING in the Dark Subtraction "Preprocessing" area
3.2) Gain the same as LIghts and Darks
3.3) Brightness set to ZERO
3.4) White Balance Red set to ???
3.5) White Balance Blue set to ???
3.6) Exposure set to put the Red, Blue, Green, White histograms where??
3.7) Bias NOT selected
3.8) Monochrome NOT selected

4) Fill Pre-Processing Area
4.1) Browse to find the Darks that were created
4.2) Browse to find the Flats that were created

5) Start Live Stacking

Thanks!!!

Mark

BlackWikkett
Posts: 121
Joined: Sat Jun 23, 2018 8:48 pm
Contact:

Re: Live Stack with Flat Frame Bug?

Post by BlackWikkett » Tue Mar 12, 2019 3:29 am

This is for ASI294 this is the process that I use

1 Lights setup
1.1 = Correct will depend on your OTA and light gathering but for the most part keep the Bightness/offset low
1.2 = Once you determine your exp, gain, brightness use Smart Histogram to align red, green and blue histogram peaks with the red and blue white balance sliders. Will not be perfect, you'll compensate with color controls in Live Stacking (I usually skip this and keep the Red and Blue at 50, mid point. This allows creating a neutral dark library but you'll need to make more aggressive adjustments in Live Stacking)

2 Dark setup
2.1 - 2.5 all settings exactly as your lights, very import to follow this!

3 Flats
3.1 Correct
3.2 depends, higher the gain more noise but shorter exposure, lower gain less noise but longer exposure, i use 120-300 gain and adjust exposure to move the highest part of histogram, usually the green channel in the 90% area of the horizontal axis of the histogram
3.3 Correct
3.4 Red set to 50
3.5 Blue set to 50
3.6 see 3.2
3.7 select BIAS
3.8 select MONO

4. you have it correct for calibration frames

What I've outlined above is the process I use. I've also created a dark library with varying exposure and gain settings. The flats are done every time I image once I've completed polar alignment and focusing. I don't have a permanent setup but if you do you may be able to reuse the flats for several sessions if nothing in your imaging train changes.

https://www.nightskiesnetwork.com/ community of live imagers and several avid SharpCap users. Come on by we'll be glad to help you out.

One thing to keep in mind about the 294 it's a very sensitive beast but an excellent camera once you get it tamed.

poolemarkw
Posts: 54
Joined: Mon Mar 26, 2018 5:49 pm
Location: Indialanatic, FL

Re: Live Stack with Flat Frame Bug?

Post by poolemarkw » Tue Mar 12, 2019 4:05 am

Thanks! A couple points of clarification:

Darks: Are the White Balance levels important? You can't exactly build a Dark library in advance if you don't what these Red and Blue levels need to be in advance, right? If so, then what settings should be used for the Darks when building a library in advance?

Flats: For step 3.2, you are NOT using the same gain setting as the LIghts and Darks? If not, how are you deciding what gain to use?

AFTER you have created the Darks and Flats and entered them into the Pre-Processing field, the histogram changes. Do you do a FINAL white balance for the Red and Blue channels to get them aligned again before starting the Live Stacking?

Mark

BlackWikkett
Posts: 121
Joined: Sat Jun 23, 2018 8:48 pm
Contact:

Re: Live Stack with Flat Frame Bug?

Post by BlackWikkett » Tue Mar 12, 2019 5:17 am

Darks: Are the White Balance levels important? You can't exactly build a Dark library in advance if you don't what these Red and Blue levels need to be in advance, right? If so, then what settings should be used for the Darks when building a library in advance?
You can create the library in two different ways.
1 - leave the red and blue white balance at 50 and do all the white balance in live stacking using the live stack color controls.
2 - use a general setting for red and blue white balance and use this while creating your dark library. This R & B white balance will be dictated by your image train and any filters you use like UV, IR and or LPS. This will allow you to get close and then you'll need to make very small adjustments with the color sliders in live stacking. The reason this is important is the red and blue white balance adjusts data at the camera before SharpCap makes adjustments.
Flats: For step 3.2, you are NOT using the same gain setting as the LIghts and Darks? If not, how are you deciding what gain to use?
You need a gain setting high enough to keep the exposure low but not to high generating to much shot noise. My general rule of thumb is flats less than one second. My normal flats are shot with 300 gain and about 209 ms. Your gain and exposure will be dictated by your image train and what you're using as a light source for your flats. In my case I use a LED tracing tablet and a T-shirt. The main thing you should worry about is the histogram when choosing your exposure and gain. Don't go too low and don't over saturate the highest part of the curve stay under 95% of the the horizontal axis. Since your using a one shot color you'll have a red, green, blue and white curve in the histogram. In my case I'm using a IDAS D1 LPS filter and the green channel is the highest curve that I try to keep no higher than 95% on the horizontal axis.

AFTER you have created the Darks and Flats and entered them into the Pre-Processing field, the histogram changes. Do you do a FINAL white balance for the Red and Blue channels to get them aligned again before starting the Live Stacking?
Yes
The live stack histogram becomes live once you have two frames stacked. If you've previously adjusted the red and blue white balance you color curves should be fairly well aligned. Now take a look at the small display histogram. Any adjustments to red green and blues sliders in the live stack histogram will show up here. Adjust the color sliders and watch the color curves align in the display histogram. In the live stack histogram start by clicking auto stretch and auto white balance then adjust as needed using your live stack image and display histogram as a guide

poolemarkw
Posts: 54
Joined: Mon Mar 26, 2018 5:49 pm
Location: Indialanatic, FL

Re: Live Stack with Flat Frame Bug?

Post by poolemarkw » Tue Mar 12, 2019 2:31 pm

Hi BlackWikkett,

I asked:
"AFTER you have created the Darks and Flats and entered them into the Pre-Processing field, the histogram changes. Do you do a FINAL white balance for the Red and Blue channels to get them aligned again before starting the Live Stacking?"

You Replied:
"Yes
The live stack histogram becomes live once you have two frames stacked. If you've previously adjusted the red and blue white balance you color curves should be fairly well aligned. Now take a look at the small display histogram. Any adjustments to red green and blues sliders in the live stack histogram will show up here. Adjust the color sliders and watch the color curves align in the display histogram. In the live stack histogram start by clicking auto stretch and auto white balance then adjust as needed using your live stack image and display histogram as a guide"

My Comment:
You are indicating making final changes using the sliders in the Live Stack histogram, which I understand have no effect on the data that would be saved in a 16-bit stack, but rather only change the appearance on the screen and if "Save as Viewed" is used. Correct? My question above was whether the Red and Blue White Balance controls in the Camera Control area should be used to make final adjustments, because they affect the actual data that gets saved when "Save as 16-Bit" is used, which is what I do to get the final .FITS file that I process. My goal is to get the most balanced set of 16-bit fits data possible.

Thanks Again, I can't express how much I appreciate your help with this.

Mark

User avatar
admin
Site Admin
Posts: 2413
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Live Stack with Flat Frame Bug?

Post by admin » Tue Mar 12, 2019 10:16 pm

Hi,

My approach is to never touch the colour balance controls that come with the camera (leave them at their default settings or set them back to those if you have changed already). The problem is that for most cameras the colour balance is performed as a digital manipulation of the post ADC image data, meaning that it is somewhat destructive to image quality. I believe there are a few cameras where the colour balance controls actually are implemented through separate analogue gains for the R/G/B channels, which would be fine to use, but it is unclear which manufacturers or models work this way.

So, the goal is to do the minimum amount of manipulation of the image data prior to stacking.

With regards to flat frame and dark frame correction, all of the controls on the right-hand side with the exception of the post processing block can potentially affect the image that comes from the camera into SharpCap. Any of these that clearly make changes to the live image from the camera should be kept the same between dark frames and image frames and should only be changed cautiously between flat frames and image frames.

Cheers, Robin

poolemarkw
Posts: 54
Joined: Mon Mar 26, 2018 5:49 pm
Location: Indialanatic, FL

Re: Live Stack with Flat Frame Bug?

Post by poolemarkw » Fri Mar 15, 2019 5:57 pm

Hi Robin,

My camera is the ZWO ASI294MC. Given that, what do you recommend that I do?

1. Initial Camera Settings - After selecting my desired Gain, Exposure, and Brightness, should I
a) Adjust the Camera Image Control White Balance Red and Blue sliders to align the red, blue, green, white histograms?
b) use the "Auto" setting for both?
c) set them both at 50%?

2. After Creating/Selecting a Master Dark - The Histogram changes after selecting a master dark into the Preprocessing area. Should I:
a) re-adjust the Image Control White Balance Red and Blue sliders to realign the peaks
b) leave them at the "Auto" Setting
c) leave them at 50%?

3. After Creating/Selecting a Flat - any further tweaks to Image Controls White Balance Red and Blue sliders at this point?

As you can see, I'm looking for extremely specific instructions regarding how to best use SharpCap to get the best results with my final "Save as 16-Bit" image that I'll process.

Mark

BlackWikkett
Posts: 121
Joined: Sat Jun 23, 2018 8:48 pm
Contact:

Re: Live Stack with Flat Frame Bug?

Post by BlackWikkett » Fri Mar 15, 2019 7:40 pm

1. Initial Camera Settings - After selecting my desired Gain, Exposure, and Brightness, should I
a) Adjust the Camera Image Control White Balance Red and Blue sliders to align the red, blue, green, white histograms?
b) use the "Auto" setting for both?
c) set them both at 50%?
You can but once you set this R & B sliders you'll want to use the same exact settings to make the master dark. "Auto" will only work at exposures of 250ms or less. I use 50% for both and make all adjustments in the RGB sliders in live stacking. Then a final white balance with Photoshop.
2. After Creating/Selecting a Master Dark - The Histogram changes after selecting a master dark into the Preprocessing area. Should I:
a) re-adjust the Image Control White Balance Red and Blue sliders to realign the peaks
b) leave them at the "Auto" Setting
c) leave them at 50%?
you'll want to make any further adjustments in Live Stack RGB sliders. If you initially white balanced with the R & B sliders and used this setting to make the dark the histogram should still be fairly close to alignment. Main thing is to keep the R & B sliders the same values for lights and dark frames. Small adjustments usually OK but I would keep any adjustments to the R & B sliders to a minimum. Do all further adjusting in the Live Stacking RGB sliders. This is also where you'll make your initial stretch then you can tweak the stretch in the display histogram
3. After Creating/Selecting a Flat - any further tweaks to Image Controls White Balance Red and Blue sliders at this point?
Make sure you create the Flats with 50/50 for R / B sliders, low brightness as described in previous post. Everything in the image train and pre and post processing will have an effect on the image which includes color balance. I would keep away from further R & B slider adjustments and do everything in the RGB sliders in Live Stacking
As you can see, I'm looking for extremely specific instructions regarding how to best use SharpCap to get the best results with my final "Save as 16-Bit" image that I'll process.
Many users of SharpCap and ASI294 that broadcast regularly https://www.nightskiesnetwork.com/ My main camera that I use for live stacking in SharpCap is the 294. I usually broadcast but haven't had good weather lately

poolemarkw
Posts: 54
Joined: Mon Mar 26, 2018 5:49 pm
Location: Indialanatic, FL

Re: Live Stack with Flat Frame Bug?

Post by poolemarkw » Fri Mar 15, 2019 8:44 pm

Thanks BlackWikkett, more great info!

- After you've finished capturing all of your frames, which "Save" option are you using, and what format (FITS, etc) are your saved files?
- What is your method for doing the White Balance in Photoshop?

Mark

Post Reply

Who is online

Users browsing this forum: admin and 0 guests