Mono images with ASI1600MC-cool

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kevin.mcde
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Mono images with ASI1600MC-cool

Post by kevin.mcde » Wed Aug 23, 2017 5:24 am

First post on here.
I like the SharpCap software...very easy to understand. However, I did my first run with my ASI1600MC-cool (and first with SharpCap as well) last week and the final stacked image in Deep Sky Stacker was monochrome.

After checking on a few other forums and changing the DSS settings the final stack was still mono. I'm wondering if I have something set wrong in SharpCap. I did use the default settings with the Color set a Raw 16 for fits files. Is there something else I need to be looking at?

I did a search on this forum but didn't see anything along this line. If I missed it and this has been addressed then I apologize in advance.

Thanks
Kevin

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admin
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Re: Mono images with ASI1600MC-cool

Post by admin » Wed Aug 23, 2017 8:07 am

Hi,

there is a setting in DSS to tell it to debayer 16 bit FITS frames which you need to set (and tell it the right bayer pattern). You can also debayer in a program like PIPP and then stack the debayered images.

The DSS settings are shown in this post - https://www.cloudynights.com/topic/5788 ... y-stacker/.

cheers,

Robin

kevin.mcde
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Re: Mono images with ASI1600MC-cool

Post by kevin.mcde » Wed Aug 23, 2017 2:13 pm

Thanks. I tried the settings and still getting mono.
Here are my original capture settings for the test run if it helps. I thought I had used RAW 16 fits but looks like it was 8 instead.

[ZWO ASI1600MC-Cool]
Debayer Preview=On
Pan=0
Tilt=0
Output Format=Fits files (*.fits)
Binning=1
Capture Area=4656x3520
Colour Space=RAW8
Hardware Binning=Off
High Speed Mode=Off
Turbo USB=80
Flip=None
Frame Rate Limit=Maximum
Gain=139
Exposure=120
Timestamp Frames=Off
White Bal (B)=95
White Bal (R)=52
Brightness=10
Gamma=47
Temperature=-17
Cooler Power=100
Target Temperature=-21
Cooler=On
Auto Exp Max Gain=300
Auto Exp Max Exp=30
Auto Exp Max Brightness=100
Mono Bin=Off
Apply Flat=None
Subtract Dark=None

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turfpit
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Re: Mono images with ASI1600MC-cool

Post by turfpit » Wed Aug 23, 2017 3:14 pm

Kevin

I have just been through this with M27 viewtopic.php?f=16&t=297. I had some RAW8 captures, taken with an ASI120MC, which would not debayer in DSS. The RAW16 captures which produced the image in my post debayered fine.

I am looking into whether or not I have made a mistake (usually the case) or have come across some limitation in DSS. Interesting that you have the same.

Perhaps someone can throw some light on this? I just found this post https://www.cloudynights.com/topic/4468 ... -stacking/ - there might be something in this.

Dave

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Re: Mono images with ASI1600MC-cool

Post by admin » Wed Aug 23, 2017 4:04 pm

DSS will only debayer 16 bit mono frames for some reason that obviously made sense to its authors. If you have 8 bit RAW frames then you will need to debayer them in PIPP or similar before stacking.

cheers,

Robin

kevin.mcde
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Re: Mono images with ASI1600MC-cool

Post by kevin.mcde » Wed Aug 23, 2017 8:43 pm

Ok. I'll try running the RAW 16 next time.

I did try to debayer my RAW 8 in PIPP but without success.

Ahh....learning curves!!

Thanks for the help.

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Re: Mono images with ASI1600MC-cool

Post by turfpit » Wed Aug 23, 2017 10:45 pm

Robin - thanks for the 8-bit RAW info in DSS.

Kevin

I thought I had this sorted when I wrote viewtopic.php?f=35&t=254. Looking at it again, the images that were debayered in PIPP were RAW8 PNG files generated by an ASI224.

I am having trouble with RAW8 FITS files generated by an ASI120MC, you are having trouble with RAW8 FITS files generated by an ASI1600.

I wouldn't mind having a look at your FITS files and try to work out what is going on. If you want to, then PM me to sort out an upload somehow.

Dave

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Re: Mono images with ASI1600MC-cool

Post by kevin.mcde » Thu Aug 24, 2017 2:01 am

Is there any benefit of using PNG versus FITS files? I certainly don't have a problem using PNG files if there isn't much of a difference.

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Re: Mono images with ASI1600MC-cool

Post by turfpit » Thu Aug 24, 2017 7:25 am

Kevin

Have a (thorough) read of http://docs.sharpcap.co.uk/2.9/#Camera%20Basics, that should help make an informed choice.

Dave

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Re: Mono images with ASI1600MC-cool

Post by turfpit » Sat Aug 26, 2017 11:37 am

Kevin

Which DSO is this?

Looking in the ZWO User Group, the debayer pattern for an ASI1600MC-cool is GRBG but keep this in mind http://www.zwoug.org/viewtopic.php?f=21&t=6480. If Flip is used, then the debayer pattern gets changed.

There seems to be active debate in astro forums about which is the correct debayer patter for the ASI1600MC-Cool, with the ZWO owner suggesting GRBG (and he should know). Perhaps unwittingly, 'image flip' has played a part.

For the images in this discussion, colour space was RAW8, Output was FITS and Flip was None (see the settings file above). Because the images were captured as RAW8 the resultant 8-bit FITS files were unable to be debayered in Deep Sky Stacker (DSS will debayer 16-bit FITS). The result was a monochrome image with a check pattern overlay.

This is debayered as GRBG, stacked in Deep Sky Stacker with green adjustment applied, black point set and curve stretched in GIMP and cropped to show only the significant feature on the image. Not bad for a quick and dirty post-process but YMMV ;)
GRBG-final.PNG
GRBG-final.PNG (121.25 KiB) Viewed 1247 times

A sample of 5 captures were debayered in PIPP and the resultant FITS files stacked in DSS, resulting in a coloured image with no check overlay. Minimal post processing was carried out in GIMP. No attempt was made to adjust colour. All 4 debayer patterns were used in PIPP. These are the outcomes (cropped to show the main feature of the image, as the output images are 70Mb and 4000x2000 pixels).

GBRG.PNG
GBRG.PNG (44.68 KiB) Viewed 1247 times
BGGR.PNG
BGGR.PNG (46.66 KiB) Viewed 1247 times
RGGB.PNG
RGGB.PNG (53.37 KiB) Viewed 1247 times
GRBG.PNG
GRBG.PNG (33.69 KiB) Viewed 1247 times


Below is a brief description of the process followed. If there is enough interest, I can work this up into a HOWTO document which would be more helpful to those starting out with all this (such as me!)

This is one of the original capture files opened in FITS Liberator. Note the 8-bit and the check pattern. Also the histogram is a 'good' shape for a DSO - offset from the LHS (no loss of data) and tailing off to the RHS (minimal over-exposed pixels).
RAW8-FITS.png
RAW8-FITS.png (39.57 KiB) Viewed 1246 times

The 5 files were loaded into PIPP. On the 'Input Options' tab, 'Debayer Monochrome Frames' was selected and 'GBRG' was selected. On the 'Output Options' tab, FITS was selected as the output format. On the 'Do Processing' tab, 'Start' was clicked.

A PIPP processed file opened in FITS Liberator looks like this. Check pattern now gone, whether or not the colours are right is another issue.
debayered-FITS.PNG
debayered-FITS.PNG (66.71 KiB) Viewed 1247 times

The 5 PIPP output FITS files were loaded into Deep Sky Stacker and processed. These were the DSS settings used:
DSS-settings.PNG
DSS-settings.PNG (12.18 KiB) Viewed 1247 times
The DSS output looked like this. The Green is slightly out of alignment but can be adjusted by the slider. A file called Autosave.tif was created.
DSS-output2.PNG
DSS-output2.PNG (26.07 KiB) Viewed 1247 times


The autosave.tif file was loaded into GIMP. Using Colors > Curves, the black point was set and a stretch applied. The processed image was exported as a PNG.

GIMP-before.PNG
GIMP-before.PNG (23.03 KiB) Viewed 1247 times
GIMP-adjust-black-point-and-stretch.PNG
GIMP-adjust-black-point-and-stretch.PNG (28.23 KiB) Viewed 1247 times
Due to file sizes, the output was cropped and colours reduced using FastStone Image Viewer.

The above process was repeated using debayer patterns of GBRG, BGGR, RGGB, GRBG, in order to see which is the best result.

The sizes of some files created during the above process:
  • Original FITS capture 16Mb
  • Debayered FITS 48Mb
  • TIF output from DSS 150Mb
  • Working copy in GIMP 600Mb
  • Exported PNG from GIMP 70Mb
Software used:
  • PIPP v2.5.9
  • Deep Sky Stacker v3.3.4
  • GIMP v2.9.5 (will process 16-bit TIF without data loss)
  • FastStone Image Viewer v6.3
Deep Sky Stacker and the debayering of 16 bit FITS files. From the menu
DSS-options.PNG
DSS-options.PNG (4.67 KiB) Viewed 1247 times
select the checkbox and choose a debayer pattern from the dropdown
DSS-debayer-16-bit-FITS.PNG
DSS-debayer-16-bit-FITS.PNG (19.97 KiB) Viewed 1247 times


For completeness, the PIPP output was tested with FITS, PNG and TIF. All 3 output types were able to be stacked in DSS.

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