Siril's Generalized Hyperbolic Stretch: A Powerful Tool for Astrophotographers

In this tutorial we'll explore the powerful transformation technique, Generalized Hyperbolic Stretch within Siril.
Generalized Hyperbolic Stretch is a technique that allows you to enhance the details and bring out the faint structures in your astrophotography images. It works by stretching the pixel values in a non-linear way, which enhances the contrast and reveals the hidden details in the image.
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[@DeepSpaceAstro]

Please consider supporting this channel on Buy Me a Coffee!: www.buymeacoffee.com/deepspaceastro

[@fasullamail]

Yours might be the best astrophotography channel on the tube. 🌌😉

[@DeepSpaceAstro]

Thank you so much!!

[@meibergstrmandersen9181]

This is cool, I am a newbie, and your videos are excellent. Very helpful. Great channel.

[@DeepSpaceAstro]

Thanks so much!

[@skyhookbix]

Rich, tanks so much for the really informative video. It is reallly hard to find good videos on Siril, most of the GHS videos are made for Piixinsight, this really cleard up sticking points. I really like your style of instruction, clear and consice.

[@DeepSpaceAstro]

Glad it was helpful! Thank you!

[@refetastro]

I love how easy slow and clearly you explain the video Thanks so much

[@donbatesster]

Rich, thanks so much for the excellent tutorial. I have learned a lot from your guidance. Clear skies, Don

[@DeepSpaceAstro]

Glad to hear it! Thanks!

[@ross1972]

Iv watched quite few Siril videos and most assume you know quite a few things about histograms which a beginner like me just has no idea. You explained in a short time so much. Im really grateful and now will have to watch all your other tutorials. The other thing I learnt is just how powerful Siril is.

[@DeepSpaceAstro]

Great to hear! I'm glad it's been helpful! Thanks!

[@miksmax]

By far the best explanation of the GHS. Thank you!

[@DeepSpaceAstro]

Thanks so much! Glad it was helpful!

[@JoeBob79569]

At the moment I'm experimenting with using the Highlight Protection, a lot. I do a bunch of small stretches, and for each one I'm dropping the highlight protection down to about 50%, or just making sure the highlights aren't blown out. It's handy for objects with a really bright core like galaxies or the Orion nebula, because you can bring out a lot of the dimmer parts of the image without blowing out the core. But my problem is that I just never know when to stop, and I always go a little bit too far!

[@DeepSpaceAstro]

Thanks for posting that! It really helps myself and others to see the different ways of stretching! I know what you mean about over doing it. I'm the same way. I've started walking away from what I'm working on for ~10min., then come back to it. Sometimes I look and think, "Whoa that's way over done!" when I thought it looked good prior.

[@oscarfernandez8477]

thank you so much!!! now that you explained this i was also able to do a mineral moon with siril, im editing everything now with siril after watching all your videos, i have better stars with starnet,better nebulas you even solved all the installation problems for m1 and i dont have to pay for a pixinsight, you are the best!!!

[@DeepSpaceAstro]

Thanks so much for the kind words! Really happy to hear the videos have helped. Thanks!

[@RetiredFE]

New user to Siril. That was an excellent explanation. I've had a lot of trouble with this but now I'm beginning to understand it. Thanks for the video. Appreciate it.

[@DeepSpaceAstro]

Glad it helped! Thanks!

[@TelfordO]

Another Fantastic Video, thank you. Stay spacey.

[@DeepSpaceAstro]

Thank you! lol

[@RyleyI]

I really like the video. You answered a lot of questions I had on what the various sliders and controls do. I'll be referencing this vid for awhile. Thx

[@DeepSpaceAstro]

Thanks! Glad it was helpful!

[@baranjen]

Brilliant. Thanks so much for all the effort you put into your videos

[@DeepSpaceAstro]

Glad you've found them helpful! Thanks!

[@Phenolisothiocyanate]

Followed this and got a final image of the Orion region that is as good or better than images from big name youtubers... nobody was more shocked than me! (First time attempting a deep sky stack with a tracker, I might add.)

[@DeepSpaceAstro]

Fantastic! Great job!

[@spookysandwich1355]

brilliant tut as usual , i use this to stretch now and with your awsome tips👍 game changer for star colour

[@DeepSpaceAstro]

Thank you! Glad it helped!

[@tehriskies-awindowtospace7270]

Thank you. Brilliantly explained.

[@DeepSpaceAstro]

Thanks so much!

[@yervantparnagian5999]

Once again a rock solid vid.

[@DeepSpaceAstro]

Thanks!

[@benjamincasatimcintosh2918]

great demonstration, thanks

[@DeepSpaceAstro]

Thank you!

[@1957Charie]

Thanks Rich. I had been playing around a bit with the GHS in the current version of SiriL. I somehow got an image set to really pop but I was having trouble recreating it on different data sets. The addition of the histogram display in the current beta version is a very welcome addition. Really lets you see what is going on. As always your videos are really helpful and very straight forward.

[@DeepSpaceAstro]

Yeah it's definitely a process. Thanks!

[@1957Charie]

@@DeepSpaceAstro This convinced me to download 1.2.0-beta2. What a difference having your tutorial and the histogram displays in the GHS tool! Played around with a 2 hour wide field exposure I took of M42 recently. Still a work in progress but the result looks like I will need to make only a few minor adjustments in PS.

[@DeepSpaceAstro]

@@1957Charie Awesome! Great to hear!

[@davechaton6771]

Great overview video on the GHS I've watched differnet videos on the tool for PI and each one gives me a little more insight (pun intended) to its function. Your video is a good example.

[@DeepSpaceAstro]

Thank you!

[@larryhibbitts2099]

Nice video! I use Siril for stacking, but I may do a little more editing with this to test it out.

[@DeepSpaceAstro]

Thanks! Yeah it's come a long way, especially with this beta release!

[@indysbike3014]

I always have problems getting good starcolors. Good to know it can be fixed.

[@DeepSpaceAstro]

Yep. It's a process, but with GHS we have much better control.

[@tonybailey3944]

Thanks Rich, your tutorials for Siril are the best around. All the relevant info concisely communicated & a game changer for me. 👍

[@DeepSpaceAstro]

Great to hear! Thanks so much!

[@RyleyI]

Thanks!

[@DeepSpaceAstro]

No problem and thank you!

[@astrolibrarian]

I just discovered your channel and you taught me how to use Siril, thanks! I have one question though… is there any way to save an auto stretch? On most images I can do a better stretch, but on a few a good starting point would be the auto stretch itself…

[@DeepSpaceAstro]

Yep. After you set it to AutoStretch, click the button with the Camera icon in the top-right corner. Click 'Save as unique file' and it will save the image as a .png in your working directory.

[@DeepSpaceAstro]

Oh wait. I think you may have meant save the autostretch and then continue stretching from there? If so, Open the Histogram Transformation, click the button with the gear to apply the autostretch, then click Apply. You should probably run a background extraction, and color calibration before that though for the best results.

[@astrolibrarian]

@@DeepSpaceAstro This feature can at times be very helpful. I have an image of the Flame & Horsehead that I can't seem to stretch as good as Siril (or the Seestar), and I'd like to try using Siril's auto stretch as a starting point to make it even better. Thanks for the tip!

[@astrolibrarian]

@@DeepSpaceAstro I have another question for you. I was watching one of your Siril videos and you were teaching how to color correct the stars... but I forgot which video it was because I have watched so many in the last few days? Do you remember which one it is?

[@DeepSpaceAstro]

Oh boy. lol I talk about stretching the stars back in changing the color stretch model to human or even weighted in this video. Maybe this was the one? kzbin.info/www/bejne/gnS4m4R5d7WBmbs

[@jesuschrist2284]

Great video, but i stll find ghs too fiddly and unintuitive. You've done the best ive seen to explain it though, ty :)

[@DeepSpaceAstro]

Yeah definitely something you have to keep playing with to get the hang of.

[@jesuschrist2284]

@@DeepSpaceAstro im starting to think i shouldn't have deleted some of my first data, as you've improved my processing skils from zero to images im ok showing to strangers in just a couple of hours. Astrophotography needs storage space like cern. (For example) A mosaic of 6 drizzled tiffs will be about 5gb alone. Plus autosave of 5gb lol. Plus the copy i make plus intermediate saves oh and then starless and starmasks. So about 50gb plus capture data per target. Its not funny :( Keep up the fantastic work and any swsa gti + nina + dslr videos would be warmly welcomed :)

[@Chorge1972]

Superb helpful

[@DeepSpaceAstro]

Thanks! Glad it helped!

[@Chorge1972]

@@DeepSpaceAstro it really did! Played a lot already, and was quite successful… but you really brake it down to the most important basics! And: 1000 thanks for your „hubble-script“!!!

[@DeepSpaceAstro]

@@Chorge1972 That's great to hear! Thanks so much!

[@benjamincasatimcintosh2918]

oh hell yeah

[@DeepSpaceAstro]

So I take it you'll be there? 😂😂

[@benjamincasatimcintosh2918]

@@DeepSpaceAstro hell yeah, every time i watch one of your videos my procesing takes longer lol

[@DeepSpaceAstro]

@@benjamincasatimcintosh2918 HaHa!!

[@DeepSpaceAstro]

@@benjamincasatimcintosh2918 Do you have your bell icon for notifications turned on? If so did you get a notification earlier than 30 minutes before start time?

[@benjamincasatimcintosh2918]

@@DeepSpaceAstro yes

[@grahamprescott9426]

Can you just do a auto stretch and then go in here to set a mid symmetry point to tidy up?

[@DeepSpaceAstro]

Sure but sometimes that method is a little aggressive, but you could always try to adjust with the inverse stretch in GHS afterwards. In the end it's what looks best to you.

[@grahamprescott9426]

I've been manually stretching as normal. Not too aggressive then come in and applied ghs to brighten and improve the overall look. Seems good in combination but may try the method again now that I have rewatched your video

[@DeepSpaceAstro]

Yep. Whatever combination works for you. It's all preference at this point

[@dannyfurdon]

Rich ,so I went through this process and went to save as a tif to open in photo shop saved to 16 bit and the image is all whited out? anything i should do differently then your other 1.02 processing video Thanks

[@DeepSpaceAstro]

Were you in Linear mode when you were stretching? Sounds like you may have been set to AutoStretch?

[@dannyfurdon]

@@DeepSpaceAstro ok I'm going to run thorough it again Thanks

[@dannyfurdon]

@@DeepSpaceAstro Long day :) that was it Thanks for the quick reply. Awesome video BTW you have brought me so far in my processing its unbelievable, can't thank you enough for these videos keep em coming!!!!

[@DeepSpaceAstro]

Happy to help! Glad you have it sorted!

[@jeff5163]

Rich, does Siril have anything like WBPP?

[@DeepSpaceAstro]

Not to the degree that WBPP takes it, but the OSC_Preprocessing script does pre-process and stack.

[@christianvontotth6002]

Excellent explanation, as always. Thank you!

[@DeepSpaceAstro]

Glad you liked it! Thanks!

[@bill7194]

Starnet does not work on my laptop. I have tried every suggestion in the book. I am new to Siril. Do any tutorials exist without using Starnet? Or should I just skip that part?

[@DeepSpaceAstro]

If you haven't seen this kzbin.info/www/bejne/iH3Znpatjr1lgZI take a look and it might at least give you the reason why it's not working. You can skip removing the stars if you want to.

[@jperez6439]

Rich, great video as usual. I was happy to learn that there is a way to minimize star color loss. Thanks for your work and keep it up!

[@DeepSpaceAstro]

Glad it was helpful! Thanks!

[@ianmacdonald2307]

Once again, very useful Rich. I’ve been utterly engrossed with Siril for the past month thanks to all of your tutorials. Particularly since I’ve not had a clear (and Moon-less) night for over a month 😢

[@DeepSpaceAstro]

Thanks Ian!. I know the feeling. Clouds are killing me too!

[@tonybailey8288]

Awesome video. What do you do to ensure the stars don't blow out as part of this specific dso stretch?

[@DeepSpaceAstro]

I always use the starnet function to remove them, process the dso, then slowly stretch the stars back in.

[@dennysturcotte3736]

At last a clear explanation of what this symmetry point is , Thanks.

[@DeepSpaceAstro]

You're welcome and thanks!

[@peacequest69]

Thanks for this great howto

[@DeepSpaceAstro]

Glad it was helpful! Thanks!

[@budgie131]

Great video, very well explained, and easy to follow. GHS is a bit confusing when first looked at, but now after watching this, hopefully will be able to get better results. Thanks. 👍

[@DeepSpaceAstro]

Glad it helped! Thanks!

[@rcpattaya230]

Wow. I'm starting to understand bit by bit. Still have a long way to go, but this has been very helpful. It's a steep learning curve. Been watching this video 5 times now and practiced on my astrophotos, and I'm getting better. 😅

[@DeepSpaceAstro]

Glad it's been helpful!

[@adarsh2919]

Thanks alot mate, really a nice explanation. It helped alot! ❤️

[@DeepSpaceAstro]

Glad it helped! Thanks!

[@rayyerbury2006]

Brilliant, thanks for sharing the knowledge

[@DeepSpaceAstro]

You're welcome and thank you!

[@dinodematteis8039]

thank you Rich! great informative tutorial as usual.

[@DeepSpaceAstro]

Glad it was helpful! Thanks!

[@Tony-Elliott]

Fantastic tutorial Rich, thanks for sharing your work mate

[@DeepSpaceAstro]

Glad you enjoyed it! Thanks!

[@andreiosmolovski8800]

Very GooD job Mr. Rich! Thank you!

[@DeepSpaceAstro]

You are very welcome & thank you!

[@jimwimmer3490]

This helped me....a lot. Thanks.

[@DeepSpaceAstro]

Glad to hear that! Thanks!

[@meianoitee01]

Nice video! Cool upgrade in the camera too

[@DeepSpaceAstro]

Thank you!

[@elbass0]

Great video again Rich. Seems like you sorted the lighting in the room as well 😁

[@DeepSpaceAstro]

Haha! Yes I did and switched to my Canon from the webcam. Thanks! Had someone comment last night about the audio, but didn't say what they felt was wrong. How does it sound on your end?

[@elbass0]

@@DeepSpaceAstro The base sound is good but there seem to be 2 minor issues: - The sound during the intro is slightly out of sync. - When you jump into Siril, there's some continuous crackling noise. No idea where that is coming from.

[@DeepSpaceAstro]

Thanks Justin. I'll take another listen. Appreciate it!

[@MChasePhoto]

This was very helpful, I've dabbled with astrophotography for years but only just started using Siril and it's quite the complex program! In regards to the other comment mentioning the audio, I can hear a lot of static and popping throughout the video. It might not be as noticeable depending on your speakers but it's pretty evident on my small desktop monitors. I haven't watched a lot of your other videos (yet) but I didn't notice it in other videos. I'd be happy to fix it for you as a thanks for the great tutorial...though unfortunately KZbin still doesn't let you replace a video so you'd have to re-post it.

[@DeepSpaceAstro]

Glad to hear it helped! Yeah the static shouldn't exist in the other videos. Thanks for the offer, but like you said; I'd have to delete this one and reupload so I don't want to go down that path.

[@niraj_dave]

this really helped understand GHS..i've been using it wrong completely..not that my result got bad but it was just ok. later i tried to do more in gimp to make it look nice but it's just difficult once the data is lost. thanks for this Rich..really helps a lot.

[@DeepSpaceAstro]

Great to hear it was helpful! Thanks!

[@Lucas_Jeffrey]

omg the audio

[@DeepSpaceAstro]

What's wrong with the audio?

[@camus83489]

can you do more examples of this, with different objects like andromeda / pleides. because sometiems the histogram looks a lot different and im not sure what to do

[@DeepSpaceAstro]

Yeah the histogram will always look a bit different between data sets. It's just a matter of practicing and seeing what works for you.