Looking at Astro Cooker online image processing software

Astro Cooker is an online software that runs in a browser to perform quite sophisticated image processing to astronomical images such as a totally unprocessed stacked FITS image or TIF image produced by software such as Siril or Deep Sky Stacker.

Astro Cooker is written by Dennis Mellican. Dennis Mellican is Datarwe’s Machine Learning Ops Architect he is responsible for ensuring the data scientists and researchers are technologically resourced to perform their machine learning models efficiently and effectively. He also is expert in other IT fields. Datarwe is an Australian data-driven technology company specialising in clinical software technology.

Astro Cooker is currently a well functioning Beta and is a derivative of FITS Scrubber. The URLs for the two softwares are:

• FITS Scrubber: https://astro.mellican.com/fitsviewer/
• Astro Cooker:   https://astrocooker.com/

Looking at an OSC images

The Lagoon-Trifid nebula region

The equipment comprised a Stella Mira 66 ED APO refractor with a field flattener and Altair magnetic 2" filter holder with a SkyTech LPRO MAX broadband filter; a  ZWO EAF and a SV405CC OSC 14 bit CMOS camera.  The data were capture with AstroDMx Capture.

95 x 1 minute exposures were captured of the Trifid-Lagoon nebulae region along with matching dark frames and flat fields.

The data were calibrated and stacked in Siril. As there was an assisted meridian flip during the capturing of the data, there were some slight artefacts at the edges of the stacked image. This unstretched image was slightly cropped in Siril to remove the artefacts.

Cropping the image in Siril

In fact Astro Cooker recommends that the image is cropped before submitting for processing. This makes sense as any edge artifacts could bias automatic processes.

The unstretched, unprocessed, stacked image of the Trifid-Lagoon nebulae region

Slightly stretched image in the Gimp

It can be seen that there is a slight green cast to the image when it starts to be stretched in the Gimp.

Submitting the stacked, unprocessed FITS file to Astro Cooker

When the file has 100% uploaded, it is then possible to check the box to remove the stars if this is required.

All we have to do now is the click on the 'Start' button.

Then, at the bottom of the screen, a status message will appear, and will change as the processing continues.

The status message start with 'Ordering'

The next status message tells you that you are next

Other status messages can be:

'Sharpening', 'Denoising', 'Stretching' and finally 'Delivery'.

Then, the screen changes and you are presented with the resulting image.

The image was large, so it had to be scrolled to see all of it

If it was requested that the stars be removed then a starless image is produced

From the Delivery page it is possible to download the result as a 16 bit TIF file, a FITS file, both of which can be further 'cooked' in Gimp etc. if required, and even a JPG which is not suitable for further processing. In the case of a starless image, it is also possible to download the star mask so that the stars can be subsequently added back. The TIF file, which is probably the one that most will download is available immediately, but a few minutes will have to be waited until a FITS file is ready for download.

We have already seen what the unstretched and slightly stretched image looked like. This is the result of AstroCooker processing our stacked image:

Image downloaded from AstroCooker

This image could be acceptable as it is, but a slight levels adjustment is all that is required to complete the process.

Slight levels-adjusted image

The cocoon nebula

A dataset of exposures was captured of the Cocoon nebula with AstroDMx Capture through an Altair Starwave 60 ED refractor with an 0.8 reducer/flattener, an Altair Quadband filter and an SV605CC 14 bit OSC CMOS camera. The scope was mounted on a Celestron AVX mount.

Equipment used

Only 35 minutes worth of 5 minute exposures were captured of the Cocoon nebula along with calibration frames. The data were calibrated and stacked in Siril. The resulting stacked 32 bit FIT file was, of course very dark:

The original stacked image of the Cocoon nebula

This image was uploaded to Astro Cooker.

The Astro Cooker Delivery page

The 16 bit downloaded image was a very acceptable image

All that was required was a slight levels adjustment to complete the processing.

The image reveals the Cocoon nebula which contain the open star cluster Collinder 470. This is located at the end of the dark nebula Barnard 168 which has the appearance of a dark lane leading to the stars and nebulae of the Cocoon.

Looking at a narrowband  images.

The Rosette nebula

The Rosette nebulae was imaged with AstroDMx Capture, a William Optics Super Zenithstar 81mm ED Doublet APO refractor at f/5.5 with x 0.8 reducer/flattener, and an Altair 2" magnetic filter holder v2 fitted with  a 7nm H-alpha, or a 6.5nm OIII filter or a 7nm SII filter and an SVBONY SV605MC monochrome, cooled CMOS camera.

30 minutes worth of 5 minute exposures were captured by AstroDMx Capture of the Rosette nebula through each of the SII, H-alpha, OIII filters, along with calibration frames.

The three sets of images were calibrated, registered, stacked and co-aligned in Deep Sky Stacker. The three resulting SII, H-alpha and OIII stacked images were combined into an SHO, RGB image in the Gimp 2.10.

The resulting image was, of course, very dark

Slightly stretched image

When the image is stretched slightly it can be seen that as expected, the nebula is very green and there is a general magenta-blue cast the the image.

The unstretched image was submitted to Astro Cooker and the Delivery page showed the processed image.

It can be seen that the image is quite well balanced as an SHO image.

The 16 bit TIFF as downloaded from Astro Cooker

When the magenta saturation is reduced to balance the stars, slight Levels and Curves correction with a little selective colour saturation processing, all in Gimp 2.10; an acceptable Hubble Palette image can be produced.

Final SHO image of the Rosette nebula

This image could be acceptable as it is, but with a little selective colour processing, the colours can be further manipulated gently if required:

It will be noticed that the image requires cropping to remove the stacking, co-alignment artifact at the top of the image. If this was to be done it should be done as early in the process as possible, but it was decided to leave the image uncropped. It might be important to crop before submission if there are large regions of stacking artifact around the edges of the image, unlike in this image.

The Pacman nebula.

Using the same equipment that was used for the previous image

30 minutes worth of 5 minute exposures were captured by AstroDMx Capture of the Pacman nebula through each of the SII, H-alpha, OIII filters, along with calibration frames.

The sub-frames were calibrated, registered and stacked in Siril. The resulting stacked images were co-aligned in PixInsight (PI) to the H-alpha channel and the co-aligned imaged saved out. The co-aligned images were combined into an SHO image. The rgb composited image was cropped in Siril to remove co-alignment artefacts.

The linear image unstretched for cropping. The red cropping markers can be seen

A non-destructive Autostretch was applied to aid the placement of the cropping markers as seen in the previous image

The cropped 32 bit image, unstretched

The cropped image with levels adjustment showing a bluish-green background and green nebula

The cropped, unstretched 32 bit image was uploaded to Astro Cooker

The Delivery Screen of Astro Cooker showing the processed image

16 bit TIF downloaded from Astro Cooker

After Levels and selective colour saturation and hue adjustment

The degree and type of processing applied to the image downloaded from Astro Cooker depends on the requirements and taste of the astro-imager. However, it is clear that Astro Cooker can be usefully incorporated into some work-flows.

For astro-imagers who may or may not have software such as PixInsight, Astro Pixel Processor, Adobe Photoshop, and other expensive software, then Astro Cooker can be a serious addition to their arsenal of image processing software. The Astro Cooker backend server is software that automates what most folks do in PI, Siril, APP, etc. It combines in sequence, processes that one would carry out in these and other programs, and offloads some AI work to third party apps such as GraXpert for background extraction/gradient removal. The processing includes star removal and replacement and the progress message only shows some of the processes that are being carried out. Experiment has shown that often submitting a 32 bit TIF produces the best results. I for one will be exploring the software more.

Imaging the Cave nebula (C9, Sh2-155) with AstroDMx Capture

The Cave nebula (Caldwell 9) in Cepheus was imaged with AstroDMx Capture, a William Optics Super Zenithstar 81mm ED Doublet APO refractor at f/5.5 with x 0.8 reducer/flattener, and an Altair 2" magnetic filter holder v2 fitted with  a 7nm H-alpha, or a 6.5nm OIII filter or a 7nm SII filter. An SVBONY SV605MC monochrome, cooled CMOS camera was placed at the focus. The scope was mounted on a Celestron AVX mount which was controlled by AstroDMx Capture via an INDIGO server. The scope is fitted with a ZWO AEF that is also controlled by AstroDMx Capture via the INDIGO server that runs on the imaging computer.

The equipment used

The two scopes were fitted with heating anti-dew strips as was the ZWO AEF which on a previous occasion proved to fail in cold conditions.

An SVBONY SV165 guide scope with a QHY-5II-M guide camera was used for PHD2 multistar pulse auto-guiding via the same INDIGO server. The auto-guiding was controlled by a separate Linux laptop indoors.

The scope was focused on a bright star using a Bahtinov mask.

Six 5-minute exposures of the Cave nebula were made through each of the H-alpha, SII and OIII filters, giving a total exposure time of an hour and a half. Matching dark frames were captured along with Flats which were captured through an Altair Quadband filter, and Bias frames were also captured.

The subs were calibrated and stacked in Siril. The resulting three stacked channel images were balanced in the Gimp. The three channel images were aligned, combined as an SHO palette, stars removed and the starless image denoised in PixInsight. The image was then post processed in the Gimp, Siril, PS CS2 and the stars were added back in the Gimp.

SHO image of the Cave nebula C9

Nicola is currently testing an alternative IDE for developing AstroDMx Capture for all platforms including FreeBSD. This has slowed things down a little, but this is inevitable in what has become a very large cross platform project.

The heated anti-dew strip fitted to the ZWO AEF worked and the focuser was used without issue.

Lunar imaging with a Meade RB-70, f/10, doublet refractor, an SV705C camera and AstroDMx Capture

An SVBONY SV705C OSC camera, fitted with an IR/UV cut filter was placed at the focus of an old Meade RB-70, f/10, doublet refractor which was mounted on a Celestron AVX GOTO mount.

The AVX mount was placed on marks on the ground which quickly gives quite a good polar alignment if care is taken with the placement of the tripod feet.

An SV705C OSC uncooled CMOS camera fitted with a UV/IR cut filter was placed at the focus of the scope. The mount was controlled by AstroDMx Capture via an INDIGO client and server running on the imaging computer indoors.

Click on any image to get a closer view.

AstroDMx Capture was used to send the mount to Vega which was used to focus the scope accurately using a Bahtinov mask.

The equipment used

Focusing on Vega

A VNC server was running on the imaging computer and RVNC Viewer was run on an Android tablet.

This allows the viewing of the imaging computer screen via WiFi on the tablet. (Whilst it is possible to control the imaging computer from the tablet, this was not the object). The tablet was used to look at the Bahtinov spikes while the scope was being focused manually outdoors in order to determine when focus had been achieved.

 

Android tablet computer displaying the star being focused

Once the scope was focused, AstroDMx Capture was used to send the scope/mount to the Moon.

The imaging computer and the tablet computer can both be seen displaying the Lunar preview.

AstroDMx Capture capturing Lunar data

A 1500-frame SER file was captured of the 49.5% waxing Moon. The best 80% of the frames in the SER file were stacked in Autostakkert! The resulting image was wavelet processed in waveSharp, post processed and re-oriented in the Gimp 2.10.

Slightly chroma/saturation enhanced image of the Moon

The slight enhancement helps to reveal the mineralogical variation of the Moon's surface.

Normal, unsaturated image of the Moon

The use of a tablet computer running a VNC client/viewer enables the manual focusing of a telescope when the imaging computer is not outside by the scope. The Bahtinov mask focusing on a bright star is much better than trying to judge focus with the telescope pointing at the Moon. This gives optimal focus for imaging the Moon and also planets.

Experimenting with narrowband palettes with the Rosette nebula

Starting with balanced monochrome channel images, I used our Rosette nebula Ha, OIII and SII data to produce the following palettes.

The balanced mono channels

Ha: 

OIII:

SII:

For comparison purposes we shall first show the Hubble palette and the Canada, France, Hawaii Telescope palettes.

The Hubble palette: SHO

The Canada, France, Hawaii Telescope palette: HOS

These two palettes use whole channel combinations as RGB images.

All of the palettes shown here also have gentle, selective colour processing to enhance to hues in the final palettes. Also all of the processing was done on starless images, where the stars were removed by the Gimp 2.10 plugin Starnet++.

There are however, palettes that use static factors for blending narrowband data

The 'Natural' palette

The ‘Natural’  palette is a narrowband color palette that uses a combination of Ha, OIII and SII filters to create a pseudo-natural color image. It was developed by Robert Gendler, an astrophotographer and physician.

The Natural palette uses the following formula for each color channel:

Red: 0.75 SII + 0.25 Ha

Green: OIII

Blue: 0.1 Ha + 0.9 OIII

The balanced monochrome narrowband images were blended in these proportions to produce the 'Natural' RGB channels

Natural palette image of the Rosette nebula

The ‘Gendler’ palette 

The ‘Gendler’ palette is a narrowband color palette named for Robert Gendler, who developed it as a variation of his Natural palette. 

The Gendler palette uses the following formula for each color channel:

Red: 0.8 SII + 0.2 Ha

Green: 0.6 OIII + 0.4 Ha

Blue: 0.4 OIII + 0.6 SII

Gendler palette image of the Rosette nebula

I think that this is a pleasing palette that compares favourably with the Hubble palette.

There is a bicolour palette that is commonly used that makes use of the full Ha and OIII narrowband images. This is the HOO palette.

HOO palette image of the Rosette nebula

I produced a palette inspired by the HOO palette but using blended data from the Ha & SII channels and OIII balanced monochrome narrowband images. I call this the 'SHOO' palette.

The SHOO palette uses the following formula for each color channel:

Red: 0.5 SII + 0.5 Ha

Green: OIII

Blue: OIII

SHOO palette image of the Rosette nebula

It is clear that there is scope for the experimental development of palettes and that the final appearance of each palette depends on a number of factors such as the initial balancing of the channels and the degree, if any, of selective colour enhancement.

Although this article is about static factor channel blending, it is also possible to blend channels using dynamic narrowband combinations. An example of this methodology is the FORAAX palette. The software engineer and astrophotographer Paul Hancock who goes by the Internet identity of Paulyman Astro wrote a script for PixInsight that automates the process of creating narrowband images in the Foraxx palette. The Foraxx Palette uses dynamic factors for each pixel, instead of static factors for the whole image. This kind of dynamic pixel math can be done in other software such as Siril or Image Magick and the same results achieved.