Astrophotography: The ABSOLUTE BEST way to STRETCH your Astro Image data in Photoshop [PS]! 

I just used this technique to stretch a the horse head. I used other techniques from other tutorials before and this is by far the best way. Other tutorials I have followed have ruined images that probably could have been much better. Funny thing is that the other tutorials are from people who are pretty well invested in the hobby. Thanks!

So glad I ran across this video. I've watched at least a dozen videos on stretching, from all the usual astrophotography channels, and they're all variations on what boils down to an experienced astrophotographer using instinct and gut feel to adjust curves and levels. This video feels like a completely different approach. The arc-sine hyperbolic stretch demonstrated here has made a huge improvement in my images--and it's repeatable. When I was stretching by the seat of my pants my images came out different every time. With this technique I get much more consistent results and I'm not accidentally screwing up the color balance or clipping blacks and highlights. Great technique. Game changer.

Man!!! Thank you SO much for sharing this info and for your good tutorials. I'm re-making all my astro images again; using this method, results just incredible! Thank you again!

Just came across your video and have to reiterate what everyone else has said - hands down the most easily understood PS processing tutorial I have encountered. Like that it was not too long, and would love to see followups of processing this particular image to its final iteration so as to understand your complete workflow. Subscribed and anxiously awaiting for more like it.

thanks man. almost wanted to give up astro because i couldnt bring anything useful out of my photos. appreciate helping everyone out

Your video was referred to me on a FB astrophotography page and I am so glad they shared it with me. I'm new to stretching data but I really like the method and results here compared to what I learned in another video for stretching data in Photoshop. Hoping you have a follow-up to this one to show how you did the remaining post-processing on the image. Thanks!

Easiest video to follow, good job as always!!

One of the best tutorials on stretching data in Photoshop!

Thank you for the tutorial. This is a great trick to have in one's toolbox.

Best tutorial yet on how to use this tool properly. I've had it for about a month or two but I've been over using it.

Ive just followed this Ed, very well explained and nice to have a different approach to use. Thanks.

Found this really helpful thanks. I like knowing the theory behind the curve, instead of eyeballing its good to know I can start from a known good initial stretch. I have a recent image of M42 I'm going to reprocess and see how much it changes the outcome.

Wow, thanks for this video. I also have downloaded the Arcsinh curves as well from the other video.

Excellent tutorial Thomas! Will give it a try👍

Great results! However keep in mind, according to Mark Shelly's site, Photoshop is not capable of doing a hyperbolic arcsin due to restrictions on the plotted points. His workaround was to create functional square roots of the desired curves. Two stretches must be performed back to back so they multiply to a true hyperbolic. Mix and matching the various 10x, 30x, 100x... in order to get the stretch factor you need. Im not sure stretching thrice will give you a true hyperbolic either. Nevertheless, you gave a great intro into Mark's technique. Thanks.

I appreciate your video and will attempt this technique next time I am editing

Ed Great tutorial on how to produce fantastic images using photoshop! Its great to see your workflow Cheers mate🦘🦘🦘

Would love to see a tutorial on the best way of doing Globulars !

Great video and nicely presented. The explanations are helpful where needed.

Another technique to try many thanks!!

This is a fantastic tutorial. Thanks so much.

Everyone clearly is getting great results. I'm getting a polarized mess every time and with every zoom option. I'm using subscription P.s and its all up to date. I know I have every layer set right and blend modes correct, just cant figure out whats going on. Your tutorial is easy to follow. Thanks

Ok man, you deserve way more subscribers. (I just did) Your stuff is excellent 👍 Tnx for sharing your knowledge and please keep them coming 🤞

Very nice, i will try this out for some of my deep sky astrophotography.

I'm not normally one to leave comments on videos, but the information in this video is awesome. I've just followed along with my very first stacked TIF file from DeepSkyStacker and was amazed at the information I could see. (loving the ASI294, and that bit about balancing its colour cast / RGGB filter was very helpful) So much more detail than just a simple edit in Lightroom and I can now see what you mean about 'star bloat' and 'colour bleaching'. Have now subscribed and plan to watch the rest of this series. Is there a way to follow them along in order of the editing process? I couldn't see if they were numbered in some kind of order. Thanks so much for the info and the effort in making these tutorials. ( lol , 42 comments...)

Nice video. Well explained and demonstrated. One comment, though. Can’t you complete this process in 32 bit mode? Some desirable data deep in shadows is being compromised by the early 16-bit conversion, while it looks like these steps should be available in Photoshop’s 32 bit mode. Normally the 16-bit conversion would be made after completely the initial stretching (i.e. what is done in this video).

Great video , complete new approach , thanks

Brilliant thanks

Awesome stuff!

Thanks Astro Ed💫

Anyone know if there is such a preset for GIMP?

Excellent!!

Nice method thanks for sharing

Great great video. I've been doping a landscape wide astrophotography, got my tracker few weeks ago, and I wonder if this technique would work well on wide lens shots.... Will try for sure.

good video man. thumbs up

A how to by you. Really cool. This was the most interesting thing I stumbled upon Today. I love to see how folks work. Nice you quote your source. Forest Tanaka was my biggest influence. Who is yours?

Thanks for a terrific video. One question from a newbie....Is step1, the initial color balance, necessary?, Since step 2 is to bring all the channels down to the leftmost limit without clipping, wouldnt the histograms get aligned automatically just by doing step2?

This is marvelous! How do you get that channel separated histogram in the right menu?

I’ll give this a try! Looks pretty good. Are the spikes/rays in the stars from some other processing, or natural out of camera?

Thanks again, best video i have seen so far, at the very end of this video did you then flatten the image ?

You're videos have been amazing and like others have said they are the most well explained I've seen, thank you so much! So I'm a newbie and have a 1600mm, how can I incorporate you're tutorials into a mono workflow? Should I simply assign my Ha, OIII and SII to my choice of Channels and pick up your video from there?

Would this workflow work for Andromeda Galaxy, I'm using color camera, ASI 2600MC Pro. Thank you.

you just earned a sub! 👍🏻

I following this technique alswell i am using an Atik 383L mono, now I did the RGB images using this but What should i do with my Luminance? i mean how to add that to it? or is the multiply or divide layer the actual luminance layer? as i shoot with LRGB filters.

This doesnt seem to work for me, the image looks a bit like a negative picture after stretching. Does this method work in photshop CS6?

Will this work with a normal DSLR file to pull out detail?

I'm trying to load the curves Arcsin but Photoshop says it's the wrong kind of document and will not open it. Why?

ok looks great, but would nice to see your final image as well. I have used the download arcsinh stretches, but not in this method, and especially like your meticulous color balancing. I also just got a triad ultra, so will be using that in a Bortle 9. My question is, if you have PixInsight, and do the standard stretch there...will that give a different result than doing how you did it, especially with the grey multiply/divide layers ? or is this a Photoshop "equivalent " to a stretch in PixInsight? thanks for this video!

Thank you for the video. I am new to Astrophotography and just purchased a monthly subscription to PS. How do I load the unzip the file to PS which is web based? The instructions for loading the file assumes the program is physically on your computer. Thank you for your consideration in this matter

Hi. Does anyone know if these work on a Mac? I've installed them in what I think is the right place but they don't show up in the Preset Manager to load. Any help much appreciated.

Hi Ed I have been using your method and workflow now on all my images, it’s fantastic. Gives so much more depth and colour, hard to believe that it was there waiting to be discovered. One question - on the initial channel mix alignment - I am finding that most images are too dark after stacking and all the colours are right on the left-hand side of the histogram without any differentiation between them. So I have been doing some initial curve stretching so I can separate the colours, usually after a couple of stretches the colour channel differences become apparent and I can start aligning them. Is this the correct approach or is there a better way?

OK, I'm with you up through stamp and desaturate the Grey multiply layer. I then stamp and add the Grey divide layer. Change the blend modes to Divide and Multiply. However when I begin stretching (arc sin) the image remains in grey scale. Yours doesn't. I have started this over about 5 times and the same thing happens. Suggestions? I know its something small I'm missing. Thanks for great instructional videos.

Can this process be completed with an image from L+RGB data? Once stacked in DSS, I normally use curves and levels on each colour and then combine them and then add the Lum. I find this method works great on a DSLR image.

Great tutorial. It has helped with a lot of my targets and I have re-processed them. However, it seems to fail dramatically on my M42 orion images. Any clue to why?

Very interesting! I’m eager to try this on some data, but my images from my canon 6D tend to have a red glow and the red histogram leads the other two, would I want to boost the red in my green and blue channels instead to align the histograms?

I tried this and I ended up with a stretched black/white image instead of color. I don't use these keyboard combos and I have no idea which layer you copied over to the top, at the end.

Hey Ed follow up question on this does it matter in which way you channel mix, for example the way my histogram was aligned, I had to drop the Green in my Blue channel. I'm guessing this is still fine?

why is stretching done in multiple steps? why not in one que? does it have relevance to precision?

That was interesting. But my question is, how much sense does this way of stratching make, when I remove the stars with Starnet ++ before stretching? What I understand is that it is about preventing stars from blowing out. So is there an other reson to use this stratching procedure?

Dear friend, thank you for sharing this. Could it be that in the third Arsin arc 10 I already have more swelling of stars and more saturated around them? I have tried several times and I cannot get the stars to remain unchanged with the initial image

Hi Ed. I am using this technique and, after a series of stretches, I can see color in my stars but the nebulosity still looks grayscale. It is a reflection nebula so I am expecting some blue hue. I am zoomed in beyond 67% so that's not the problem.

Thank you for the video! I tried to apply this method on my 1.5h integration of Heart and Soul in Bortle 4-5 sky on 135mm astromodified DSLR with moderate twilight pollution. ArcSinh probably (not sure yet) does a better job at stretching (final result visually looks slightly beter), comparing to simple black and midpoint Levels adjustment. However, the actual introduction of Grey Multiply and Divide method made the final image much worse. The colors look desaturated, and almost like washed out into the grey. I am not sure if this method is just more scientifically correct (more realistic color rendering), while visually less appealing??? Or is my data just not good enough for this method to show its potential? Note that my original stack shows substantial color cast and gradient due to twiligh pollution. Do I need to remove the color cast and gradient first, before applying the grey×÷ method? UPD: Tried this method AFTER removing the background. The result is the same - the image looks bleak, almost colorless, way less vivid and appealing than if no grey×÷ was used. Whats going on?

It works, but it often still bleaches the image for me. I’m probably doing something wrong but I have no idea what.

This is a great video, i now have added these to the list of things to use for astroprocessing in PS. One question, I shoot mono with filters.. So, would it be best to stretch before I combine or after in this instance lrgb, and what does this mean for narrowband imaging?.. As far as how to utilize these with false color? Tips or hints?

Can you use this when editing the MW.

what version of PS are you using?

I downloaded the arcsinh files. I put them in the same curves folder mentioned, but when I select Curves in PS, they are not there to select. Am I doing something wrong?

I have one image that has the main data towards the middle of the levels adjustment panel. There is also (height wise very small) a lot of data to the left of the main spike. Do you clip only up to the small data or go up to the main spike? It looks kinda like this " _____IIIIII_____"

Beautiful, but does not work for me. I will keep trying.

Hi I tried to send you a message on your website contact form. Don't think it went through. Basically I followed your technique using the arcsin10 adjustment but am not getting the same results. I use a DSLR and telephoto lens on a Star tracker and take about 50 to 100 lights and stack them to start my image in photoshop. My question is will your arcsinh10 adjustment process outlined in your Photoshop videos work for my DSLR image or is that for sophisticated telescope cameras that take color images in different channels?

Has anyone made an action yet?

Man...this seems complicated for someone who doesn't know much on processing in PS