 If you've watched my processing videos before, you know that I love the processing software Seral. It's available at s-i-r-i-l dot org. It's completely free and open source software developed by a team of volunteer contributors. And the reason that I'm a huge advocate for it is that it has many useful processing tools for deep sky astro photography that aren't available in any other free software. You know, things like photometric color calibration and background extraction, both of which would save you so much time and frustration if you do those early in the process. It's also a super fast pre-processor with built-in scripts that can take folders of your data, you know, your lights, your darks, your bias, your flats and calibrate, register and stack those very quickly. And yet another reason Seral is so great is that it's available cross-platform. It's on Linux, it's on Windows, and it's on macOS, which is where I'm usually using it. And today, it's gotten even better. The first beta release of Seral 1.2.0 is now available from the website. And I've been using a pre-production version for a while now and I gotta say this release is huge, it's massive. I'm not gonna be able to go over all the cool stuff that has been added and improved upon, but I will go over in depth a couple of my personal favorite new things, mainly how Seral has incorporated StarNet and the generalized hyperbolic stretch tool or GHS for short. And before I jump into the computer, I'll just say this video is not sponsored by Seral or anyone. I just really like the software, I wanna share about it. And if you do too, you can support the Seral team through buying merch like this or giving them a direct donation on the website. And my only other note is that this is a beta release, meaning that there is so much new stuff added in this release that there's probably going to be some bugs still, but that's how open-source software works. You can help them by letting them know that there's a bug by submitting an issue on their GitLab if you do find one. And then they can update it in future releases to fix any major problems. All right, let's jump in. Okay, so the first step is if you already have a version, an older version of Seral on your computer, you can delete that and download the new version right here from seral.org for your computer. There is, of course, Linux, Windows, and macOS. I am on a newer M1 Mac, so I would download the ARM macOS version like this. Okay, and then go ahead and install it and open it. And the first thing that you're going to do is change your working directory to where you want it to save files. So up here, there's this little blue home icon, and I'm just going to choose the desktop, and I've already made a folder here called Seral 1.2.0 Practice, and I'll just click open, and then you can see my working directory is set right there. Now, I'm not gonna go over all of the things that I've already gone over in other tutorials, but normally you would start if you just have your raw data with the scripts, and you can pre-process your data here, whether you're shooting mono or one-shot color, or you can go through the tabs here and do it manually. But let's just jump in with some data that's already been pre-processed, but nothing else done to it, so I'm just gonna click open and open this fit file that I've already stacked and pre-processed. So it's called Redcat Meets Blue Horse because it's the blue horse head taken with a Redcat telescope. Okay, so I'll just click open here, and it always opens in a linear view, but if you look down here, right in the middle at the bottom of your screen, you can see that you can change that to, I would suggest starting with Auto Stretch, and this usually gives a very reasonable idea of what the data actually looks like. And so this data is just a half an hour of three-minute subs, so 10 three-minute subs that I shot from a dark site with a Redcat 51 of this beautiful, huge reflection nebula, the blue horse head. I think it's in Ophiuchus or Scorpius, I can't remember which one, one of those. And other visualization things you can do here is this is an RGB preview, but you can also switch between the color channels up here. And some of the processes want you to do them on a color channel rather than on the RGB composite. So you might run into an issue if you try to do some of these things on the RGB, so then just switch to one of the color channels. Let me turn it back to linear. Okay, the first big new feature that I'm going to talk a lot about is the reworked generalized hyperbolic stretch transformations dialogue. I know that's a mouthful, so I'm going to just shorten it to GHS from now on. This new GHS tool is incredibly powerful and it was implemented with the help of the creators of GHS, David Payne and Mike Cranfield, and they've also written a tutorial on the CERL website that I've been pouring through and it is amazing. It's very detailed, it goes, and I've been sort of putting off learning GHS, but stepping through this tutorial has really taught me so much, so I'd really encourage you to read that, but I will show a few things that I've learned here too because I'm really excited about it. It seems very powerful. So the first thing is normally when I would go to stretch data, I would just be doing it through the mid-tone slider or through an auto stretch, and those are basically just going to make this curve line just sort of go like this, right? With this tool, you can get a lot more specific with how this curve actually works, and I like to think of it as, it's always sort of forming an S, so if you're a photographer, we were used to S curves, but if you've ever used a curves tool in something like Photoshop or GIMP, you know that sometimes it's hard to get the S looking exactly how you want it and to behave exactly how you want it. Well, with this tool, the S is really, really easy to make it just how you want it, and you're gonna want a different kind of S shape for this initial stretch versus stretches later when you're just trying to bring out the dust or do different things, but in any case, all of these different kinds of cool stretches you can do, the point is, is to preserve the stars so they don't get all blown out and just completely white or too big, while also bringing out all of this data that's really crunched up in the shadows area of the picture. Okay, so let's actually look at how we use this. The first thing that they suggest to do is to zoom in on your actual data here, so you can see right now we're at a zoom scale of one, but let's turn that all the way up to 100, and when I do that, you can see maybe this is some data right here, I'm not sure, but I don't see the main histogram peak, but if I scroll over, whoop, carefully, there it is right there, and so this is really zoomed in on it 100 times, and this is important to do because it allows you to better set your symmetry point, which is a very important concept with this GHS tool. The way that I think of symmetry point is I think of S for S curve, and the S is sort of the middle, the symmetry point is the middle of that S, so where it's going to sort of start changing shape, and for an initial stretch, you want it to be the symmetry point to be, I think right within your data here. So I usually have just been picking something sort of on the left edge of my histogram here, and that sets a very low value for your symmetry point, something, in my case, 0.020, and then, because this is an initial stretch, and we're stretching from linear, we're going to use a very high stretch intensity, so this B value, we're gonna set all the way over to the right to 15, and that basically is going to be the shape of the curve, so you'll see what this means in a second here, and then I'm going to zoom out, so I can show you what's gonna happen, so I'm just gonna zoom all the way back out to one, and I wanna show you what happens when we start applying the stretch factor. See that? This is the curve that it's making, and at first, when I just apply a little bit of stretch, it looks just like a normal stretch that I would do with the mid-tone slider, where it's just going out like that, but watch what happens as I continue to bring this stretch factor over. You see the odd shape that's making, and it's starting to curve back down here. See that? Like an S, because that's where my symmetry point is, that's where the balance is, they're actually in my data, so I'm gonna keep going. And look at that, look at that beautiful shape of that curve. That's very hard to make just on your own with the curves tool, but with this, it's so easy, and it creates a beautiful stretch of the data. Like I mean, look at that, that's just through doing this, I get such a nice initial stretch. You know, I can do this with just the normal histogram tool, or something pretty close, but it's so much more work, and it's not as precise as this. So I really like this, even for just initial stretching, that's really, really great. Now, there are some different options when you are stretching color, so see color stretch model. And I have it on the default, which is independent channel values. And a little bit of reading about this on their tutorial, these other ones are for, if you want to really preserve star color, like with the arc sign stretch, that kind of deal. Now, unfortunately, they don't work so well for me, like I'll just turn on one of them here, I'll turn on even weighted luminance. I'll turn down the stretch factor a little bit. Okay, so what I have found, let me zoom in now, is I have the exact same problem that I always have with arc sign stretch, where it does preserve a lot of star color in the halos and looks good in some ways, but on all of the bright white star cores, they go pure magenta. And I've always wondered why that always happens with my data, but it consistently does whenever I use, try to use arc sign stretch. So I often just avoid it, because then I have to remember to go back in and fix all of those star cores, which is not too bad, but it's a little bit of a pain to remember to do that. So if anyone in the comments can tell me why that happens with these ones or with arc sign stretch, I would be appreciative, because you can see it doesn't happen with this one, independent channel values, but with this one, we are starting to bleach out a little bit of the natural color of the halo of the stars. Really, I'd love somewhere in between these color stretch models, because I love what it's doing with the bright star halos, even though we have the magenta cores. But with some of these medium sized stars, I think it looks a little bit garish, and I like this one, the independent channel values better. So I don't know, you can play around with that. It might act completely differently with your data, but let's keep going here. I'm just gonna reset the zoom level with this button down here, fit the image to the window. And I'm gonna turn back up the initial stretch factor to something like that. So you can look at my values here. This might not work exactly the same way with your data, but I think the really important part is setting the symmetry point by zooming in and clicking in to like the left edge of your histogram bump. And then you can start, and then you can put the B value to 15 and start playing around with the stretch factor to do your initial stretch. Okay, I'm gonna go ahead and apply that. And you can see as soon as I apply it, it resets all of these values back down to zero, which is exactly what you would want because now you're going to change your symmetry point. You're gonna change all of these values with the next stretch. So I'm going to, and you can do the symmetry point in two different ways. You can either click directly on the histogram, which is the way I usually do it, or you can define a rectangle over here on the actual image. So let's say I'm just gonna click and drag and do a little one in the background over here, then click back on the window and click the eyedropper tool and you can see it sets the symmetry point based on the values in that box. So then if I start playing around with these, you can see it created a symmetry point based on that. You can always reset it right down here. So I'm gonna reset. And I'm gonna try clicking on the histogram. This time I'm gonna try on the right edge of the histogram peak. And that's actually very close to what this value was, maybe a little bit higher. And I'm just going to, actually I'm gonna leave this at zero for now. And I'm gonna start actually with the stretch factor. Then I'm gonna start playing around with this. Okay. And so this looks like your classic S-curve, right? But here's something that makes this tool even cooler. This thing called highlight protection point. What this does is it can flatten out this top part. So you get an S-curve in the part that you want, right? So let me just show you this. I'm gonna take this slider and I'm gonna move it like that. Look at that. So see it flattens out this part of the image and we still have this really nice subtle S-curve down here. You can see what it's doing over here because you're getting a live preview as you play around with this. So, you know, for me, what I wanna emphasize here is that for me, I've always felt that was serial. It's great for preprocessing. It's great for the background extraction and all of that. But I never really used it for stretching just because the histogram tool alone wasn't quite enough for me. What I wanted, the histogram stretch, I mean, what I really always wanted was to move to the GNU image manipulation program or Photoshop so I could use curves. But this is like curves, but so much better. So much more powerful because it's just so much easier to use. I can basically set any kind of curve that I want with these five sliders. And it's great for protecting the stars while bringing out the stuff that you want. Okay. And, you know, just through playing around with these, you can really emphasize different parts of the image. Like if you really wanted to make the horse head pop, you could sort of bring down this stretch intensity. Well, if you wanted to really bring out some of this background stuff, you could bring up the stretch intensity, play around with the symmetry point. And so one thing that I've heard is that, you know, this is really powerful also for bringing out IFN, the integrated flux nebula, and I totally believe it. You can really dial in a stretch just on some specific part of the image here. But like with any tool, you have to be careful because I think that it's also pretty easy to get to a sort of unnatural result where you're bringing up the background too much and you're gonna see a lot of noise in the result. But that's also true of star net processing, which is what I'm gonna go into next. All right, anyways, let's reset this because I've just been playing around and let's try to do an actual cool stretch here. So I'm gonna set the symmetry point a little bit lower than I did before. And I'm gonna take the highlight protection point a little bit down. Let's bring up the local stretch intensity and now let's try starting to stretch this. Okay, I'm gonna stop there for now because we're gonna do a lot more with this image and you'll see how the GHS tool comes up again after we do the star removal process. But the next thing that I wanna show you is that star net has been incorporated into serial along with a lot of other cool star processing tools. They're under image processing, star processing. But when you click on star net star removal, you'll see that execute is grayed out and it says no valid star net executable found in the installation directory. So let's cancel out of that and you actually have to go over here to preferences, miscellaneous and tell it where your star net plus plus installation directory is. Now, if you are on Windows and you have the star net GUI or if you are a PIX Insight user and you have the star net plugin, neither of those ones are going to work. You actually have to get the command line version of star net and point to that. If you are on Windows or Linux, all you have to do is just download it, unzip it and point to it right here and that's it and you're good to go. If you're on Mac OS, I'm going to show you right now all the steps you have to take because it's a little complicated just because of Mac OS security. So let me cancel out of this. Okay, and here in Firefox, I'm at star net astro.com and I just want to show you which version to download to use in serial. You need to download this one, the command line tool for your operating system. So I'm on Mac OS, so I'm going to click on that. Okay, and then you unzip it and this is the folder you're going to point to. You can put it anywhere on your computer. So if you want to put it in the documents folder or applications or wherever you want to put it, that's fine. Just for the ease of this tutorial, I'm just going to put mine on the desktop. Okay, and then we have to do a few things to get it ready to go for serial. So go ahead and click this magnifying glass and type in terminal and then we have to change to this directory. Right now we're in our home directory represented by that tilde. So we're just going to type in cd for change directory space and then drag in this folder into the terminal and that will copy its path right there. You can just press enter. Now we're actually inside that folder and inside that folder are all the different files that make up the program. And we need to tell Mac that it's okay to use these different files by giving them permission, by giving the operating system permission to use them. So the way to do that is chmod plus x for execute star net plus plus enter. And the same thing again, chmod plus x on the run star net dot sh file. And by the way, all of these commands are on Serals new documentation and they are also going to be in the video description. And then another one we need to do is xattr-r-d com.apple.quarantine. And then do this on both the lib tensorflow files. Okay, and that's all we need to do in terminal but then it's also going to complain the first time that we try to run this in Seral or anywhere and then you just have to open up system preferences and I'll show you that. Okay, so back here in Seral, I'm going to tell it in the preferences where my star net directory is. So you go down to miscellaneous, click into this little menu here and choose other. And I guess I'd done this before because it jumped right to it but it's on the desktop, there it is. And it should pop in right there. If you have any issues with that, you know, try just sort of restarting Seral and it should work on Mac just to choose other and pick it and then a click apply. And once you've done that, then it will, that preference will hold in the software. So you don't have to do this every time just once. Okay, and if everything seems to have worked what you can do is go down here to star processing, star net star removal and now this execute button will be blue meaning that it recognizes that there is a valid star net to executable. Now, there's a bunch of cool options here. Generate star mask is the only one that's turned on by default meaning it's going to create two files, one starless file of your work and one with just the stars that they call the star mask. What I'd recommend you also try is this recompose stars on completion. This is something that has been built just for Serals implementation of star net and I've been really enjoying playing around with it. So I would definitely recommend trying out that too. Okay, now remember the first time you apply this it's going to again not work because of this Mac security issue. So when you see that message just click cancel, go up here to the Apple, go to system preferences go into security and privacy general and you'll see this message star net plus plus was blocked. So just to make sure that this doesn't happen again and click the lock here and use the touch ID or your password so that that's unlocked and then click allow anyway. And unfortunately this might happen again so because it often will be like, okay, we're fine with star net but we don't like the lib tensorflow file. So let's see if that happens. Go down to star processing, star net star removal execute. Yep, open. Okay, and this time it should work fine and it did if you do have more issues, you might just have to go back to here and if it complains about lib tensorflow is an unidentified developer kind of thing you might just have to click allow anyway again and then relock this and it should remember all of those settings. So then from then on out star net will work and serial just fine. I know it's annoying the first couple of times but again, this is a Mac problem so it's only gonna affect you if you're on Mac like me. Okay, another cool thing about serals implementation of star net is that it can do conversion on the fly so it can understand, you know, why you're working with a 32 bit fit file but I'm gonna save that off as a 16 bit tiff file because that's how star net works. So before a lot of people would run into issues with that because they'd have to remember to save it in a specific way before they could run star net. Well, now you don't have to even think about that because serial handles it for you. All right, so we are done and one thing that I want to point out here is you might have noticed that the image already looks pretty different and that's because this image that you're seeing here is an unsaved star recomposition result, right? So this is actually the stars removed, the stars added back in through some kind of blending mode and then we get a two histograms here and two versions of GHS where we can stretch the stars and the background separately. So this is so cool. I love this implementation and you can even click on the advanced button here and get even all of the different sliders and all the different color stretch models, everything. So if you are able to do, you know, or assign stretch on the stars but a different kind of stretch on the background and all these kinds of things, you can even see here it has a bunch of different options for the kind of transform you wanna do. So it has modified arc sign, inverse modified arc sign, all these different things. Okay, so let's try this out. I'm gonna make a little box on this dusty part over here in the image and set my symmetry point to that and then I'm going to start playing around with the stretch factor. And one thing that I really like in this implementation too is that it even has this sixth slider here, black point. So I can actually also do the stretch and then move this whole histogram peak over sort of stretching it out and moving the black point over to the left here and look at how cool that looks already. I know this is just like a small preview so it's a little bit hard to see how much noise I'm stretching to. We could zoom in to see, let's see. Yeah, so it's pretty noisy but you get the idea. If this was like 10 hours of data imagine how powerful this feature is. You can see it's brought out so much cool dust in the background. I've never actually seen this much dust in my data before right now. I often don't do anything with the stars after recombining and in this case I might not again. I think maybe they could be stretched just a little bit though. So let's see. Yeah, and you know what? I think that to get a natural look I like to bring the stars back in a little bit more than I had them actually. So I think just a very subtle stretch of the stars looks really nice here. Better than just as it was before. I like to sort of have a nice balance where you get a lot of very small dim stars, some medium stars and big stars. A lot of times when I feel people like are too aggressive with this method or with star reduction, all the little stars just turn into these tiny little points and there's no sort of variation in brightness. I don't really like that. So this ability to stretch the stars separately from the background is great. And I've been playing around with these different stretch models in this tool and they're not giving me the magenta cores. So again, I'm not sure what the magenta cores is all about, but at least for me in this tool it's not happening. So anyways, this is all looking great. I'm gonna go ahead and click apply. And now we have this beautiful image. Put some final touches on it. Maybe, oh, if, you know, Cyril now has noise reduction built right in. So we could try out that. You know, there's of course normal things like color saturation that you can add, I think a bit more color saturation was necessary. So I'd maybe bring that up to about 0.66. I think that looks pretty good. When you're all ready to save this, because remember this is an unsaved recomposition of the stars and the starless. You can go up here to the save as command and either save it as a fit file if you want to continue working on it or an output file like JPEG or TIFF if you're all done. So I'm gonna save it as a TIFF. Okay, one last thing I wanna point out, maybe I should have done this earlier is that to use photometric color calibration in the new 1.2 version of Cyril, you first have to plate solve the image. It used to be sort of part of it, but they've split that off. So now you go over here to this little menu, go to image information and go to image plate solver. And this will be what you do first to basically figure out where this image exactly is. Plate solves it and adds that to the Fits header and then you use photometric color calibration. And one thing that they've added that a lot of people will be happy about is you can now download the local version of astrometry.net and that's gonna be and use that for plate solving. And that's gonna be really handy for people that have had hard to solve images, though which is usually like wide field images. Like if you're using like a 50 millimeter camera lens, a lot of times the normal plate solver fails, but now this option, you can now download that local version, which I'll have a link for and it should work a lot better. So just wanted to add that in case anyone was confused about the new photometric color calibration, you now have to go over here first, image information and plate solve your image. All right, I'm gonna leave it there. There is of course a lot more for you to discover and let me know your favorite part of the new release in the comments. You're now seeing the names of everyone who supports this YouTube channel over on patreon.com slash nebula photos. It's an excellent community of dedicated amateur astrophotographers, just people who wanna learn and are very willing to share their own expertise. We have over 800 members now. There's an active discord that you can get involved in and I can't thank my patreon members enough because I'm now doing this full time thanks to all of you and it is what has allowed me to make these videos and to really pursue this as my own business. So thank you so much to all my current patreon members and if you enjoy this channel, I think you will get a lot of benefit out of joining my patreon community. It starts at just $1 a month and for that you get a bunch of perks including direct messaging support with me, a monthly zoom chat with the whole community, a monthly imaging challenge organized on discord where we pick different targets every month and a whole lot more. So if you're interested, head over to patreon.com slash nebula photos. Till next time, this has been Nico Carver, Clear Skies.