Solar Image Processing

Stacking is the process of importing your video files where the software selects your better images, aligns them, producing a final image should be sharp and impressive.

Hi, my name is Erik and I'm an amateur astrophotographer.    In this episode,  we will explore how to use ASIVideoStack and AutoStakkert Version 4.0 to stack your imaging session and try to determine which stacking software is better.




WHAT YOU NEED TO START

For this demo, we will need video files of the Sun, our stacking software ASIVideoStack and AutoStakkert!, and I will use Photoshop to make the final edits.

If your unfamiliar on how to image the Sun, please check out my GUIDE FOR SOLAR IMAGING for more details.

To get really clear and crisp images of the Sun, I recommend taking videos of the Sun (or Moon and planets) using the lucky imaging technique.  Lucky imaging is where you use the video feature of your astrophotography camera to take a high number of short exposures so it minimizes the effect of Earth's atmosphere. 

Video files can be recorded in the SER or AVI format.   SER is preferred as it records the video file uncompressed in the highest possible quality.    The files are written in the Bayer pattern of the camera while time stamping each frame.

Check the video output settings for your video capture software.   If you are limited by memory or your computer processor is slow, consider the AVI format.

ASIVIDEOSTACK



First, lets stack our video in ASIVideoStack, which is a part of the ASIStudio software, available for download at ZWO.   This software is free from ZWO and available on their website under their downloads section.  It is very easy to use and understand.  I will be using version 1.9.5 today.   Open up the software and select ASIVideoStack.

You can either drag your video files in the right section of the window, or click the icon and load up the files.   A pop-up window will be presented to select the Bayer pattern.    Since I am using the ZWO 178MM Monochrome camera, I am selecting "They were captured by a mono camera".

Under Stack Type, I am going to select "Moon and Sun Surface"

Under Stack Percent, you can select how many of the images in the video file you want to stack.    How much?   Well, that is really hard to know.   ASIVideoStack does not provide an analysis of the quality of your frames.    If my seeing conditions were poor, or I imaged the Sun lower on the horizon, my stack percentage would be low.   If my seeing conditions were excellent, and the Sun at a higher angle above the hozizon, my stacking percentage would be higher.

ASIVideoStack allows the minimum level of stacking at 20%.   You can always run the stacking process multiple times and compare your results.   I ran the stacking percentage at 20%, 50% and 75% and saw little difference.   I likely had some good seeing conditions that day.




After stacking, ASIVideoStack gives you a number of actions available to modify your image by adjusting the Sharpness level, brightness, contract, saturation, noise reduction.   You can select the Sun Color or Invert the Image.

You can use these features in ASIStudio and complete your imaging process.   Click on your images and save them.    You can always take your stacked images and make modifications in other image editing applications.

AUTOSTAKKERT

Autostakkert is another great freeware program to stack your images.  Available for download at https://www.autostakkert.com/.  It is a little bit more involved, but the finished product is better in my opinion.   Once installed, open the Autostakkert application on your computer.


Once loaded, you want to load your video file.   Click the button 1) OPEN.   Find your video file and load it.

Once loaded, review the following options.  In the Image Stabilization, you can check SURFACE or PLANET (Center of Gravity).  Autostakkert recommends selecting surface for the Sun, Moon and deep-sky recordings.

On the Quality Estimator, I leave that in Automatic and Local (AP).  I set the Reference Frame to Automatic.   Next, click 2) Analyze.

Once the analysis is complete, look at the Quality Graph.   I am select to stack the frames that meet or exceed the 75% horizontal line on the quality graph.

I am looking to see where the green line goes below 75%.   I set the Stack Options to stack frames that meet or exceed 75% above this line on the graph.    Autostakkert designer Emil generally recommends discarding any images below the 50% quality line.   He writes in September 2016 edition of Sky and Telescope magazine "to use more frames when seeing is good, and fewer when seeing is poor."

There are some great in-depth insights on Cloudy Nights that recommend other methods when selecting the percentage of images to stack.   Be sure to check that out.

For "Super Resolution", I leave drizzle off.   Drizzling is a technique that was developed for the Hubble Space telescope to get sharper image results images that are undersampled.   

I go into more detail on proper sampling in my episode MISSING THE SUN IN MY LUNT TELESCOPE.

Next, go to the window of your image.    You can explore the different frames, adjust the zoom to view your image, and get more details of your image in this window.     We need to place an alignment point grid.    Some tips here from Emil include:

Cover your entire subject with alignment points.

Large alignment points for areas with few details

Place AP Grid button can get good results

Manually placement of AP results can get better results.

For this video, I'm going to use place AP grid.   Then press 3) Stack in the other window.

Results will be saved on your hard drive.   From there, we are ready to edit the image.

IMAGE EDITOR

You can edit your image directly in Instagram, TikTok, and other social media applications.   Here, lets edit them in Adobe Express and Adobe Photoshop.

Adobe Photoshop

Lets explore Adobe Photoshop.   Load up your image.
Next under IMAGE, I'll expand MODE in the dropdown menu, check RGB Color from Grayscale.  This will allow me to assign a color to the Sun from my monochrome image.

Next under the FILTER selection, I'll click on CAMERA RAW FILTER.   I have found that this is a powerful tool in Photoshop that allows me to make a lot of changes all in one spot.   Since my image is still in the grayscale profile, the first thing I do is assign a color to the Sun.   I expand COLOR GRADING, click the GLOBAL settings circle in the ADJUST area, and then bring the adjustment on the Global Color wheel to around the Hue 24 with saturation around 100.     Hue 24 and Saturation 100 on the Color Wheel brings the Sun color to a mild orange color.  From here, I press OK.

When I return back to the CAMERA RAW FILTER, you will notice that the color profile is now COLOR and not monochrome.

From here, I'll make adjustments in the CAMERA RAW FILTER to adjust the brightness, sharpen the image, and bring out the details that I think this image needs.    Play around with the slides on the different adjustments and see how it impacts your overall image.   If you don't like the adjustments, press CANCEL and start over.

Once you are satisfied with your work, goto FILE, click EXPORT, and QUICK EXPORT AS PNG.  

HOW TO STITCH TWO IMAGES

You may find that your field of view is not large enough to take a whole image of the Sun.   Or maybe the ZWO ASIAIR Wi-Fi Smart Camera Controller limits your region of interest (ROI) to 1080p, limiting your ability to get the whole Sun in your lucky image videos.

In this case, you can take two videos, stack them afterwards, and have to images.   In this case, you will need to merge the images into one.   Lets explore that process.   Load up Adobe Photoshop.

Under FILE, expand AUTOMATE and click PHOTOMERGE.  I keep the Layout in AUTO mode.  Load your images of the Sun.

At the bottom of the window, I select BLEND IMAGES TOGETHER and CONTENT AWARE FILL TRANSPARENT AREAS.   What this last selection does that in the event your images has some areas that are blank where outer space is at, it will make those areas black instead of transparent.   A neat feature!

Once your images has been merge together, adjust the image as before.   Once you are done, click FILE, click EXPORT, and QUICK EXPORT AS PNG.  

CONCLUSION

All that is left is to share your discoveries and excitement with your family, friends, and followers!   Hopefully this episode has given you some insights on how I process my solar images.   I'm sure there are some better ways of doing it as I am still learning and growing in this hobby.   Be sure to check out my video below on YouTube on Solar Stacking.



Also, if your like me, there are no telescopes stores my area, not even in my state.  I purchase all my astronomy gear and solar viewing gear from High Point Scientific.   They have a huge inventory of astrophotography cameras, solar telescopes, solar eclipse viewing glasses, and more.    By using the High Point Scientific link below in the description, you can help this  channel.   Thank you for your support.

High Point Scientific
https://www.highpointscientific.com/?rfsn=7755489.66ed8e

I'll leave you some words from the famous philosopher Plato.. "Astronomy compels the soul to look upwards and leads us from this world to another".   Take care.

Enjoy learning more about Astronomy and Astrophotography?   Come explore with me with my newsletters and YouTube channel.

Visit my YouTube channel for more astrophotography
https://www.astrobortle.com/

Check out my Astro-photos images on AstroBin!
https://www.astrobin.com/users/erikgigem/

For the latest Blogger updates, subscribe to my Newsletter
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