How to capture a galaxy with your DSLR, Part 2A - DeepSkyStacker and GIMP

Welcome to part 2a of ‘How to capture a galaxy with your DSLR.’ if you haven’t watched the first part, please watch that part first. The link will be in the description. It will go over the entire capture process and in this video part 2a is just the editing process where I’ll show you how to edit the pictures that we got in deep sky stacker in GIMP these are both free programs if you’re not already subscribed to this channel please subscribe and you can also support me on patreon. The link to that will also be in the description without further ado here is deep sky stacker I’ve switched over to my Windows laptop now and the reason is is because deep sky stacker is a Windows only program if you are interested in free stacking on a Mac or Linux machine I am gonna make a video about Cyril as well which also does this same kind of stacking process but I do like deep sky stacker if you do have a Windows computer because of how simple it is and it generally gives you also very good results so the first thing that I’m gonna do in deep sky stacker you may not have to do it depends on how much internal storage your computer has I know that I’m running a little bit low on local storage or internal storage so I’m going to go down here to the settings option under options and click on stacking settings then under stacking parameters this little window that opens up right here I’m going to go on to the tab all the way over to the right called output and I’ve already set it here previously but on normally this would say something like C Drive and it would put it in a temporary folder on your C Drive which is your local storage drive your internal hard drive I’m working on a laptop with a small SSD and I know that this temporary folder often grows to gigabytes and gigabytes while you’re working deepskystacker after you close out the program it does delete it but while you’re working you need a very big temp folder so what I’ve done here is I’ve cooked on this little button with the three dots and I’ve told it to instead use a temp folder that I just created on my external hard drive which here is called 2019 backup and it’s the D Drive on the computer and so whoops I just accidentally set it to the D Drive I want to set it to the temp folder on the D Drive just to keep things a little bit more organized there we go and once I’ve done that I can go ahead and click OK and it will remember that setting it will even remember that setting the next time you open deep sky stacker if you were wondering assuming you have that external hard drive connected okay next we’re going to now we’re going to actually get on to the main show which is starting at the top here over on the left and just working down this list of things to do I’m starting with open picture files and the first thing that I’m going to do is I’m going to navigate to my folder m1a1 folder that’s on my external hard drive and I’ve already organized the files into these four folders using Adobe bridge but you can also just use your file system to do this because as you can see when I open one of those folders it does give me a preview so I can see that all of these are lights if you have to see them even bigger you can change it to extra large icons and I can see that there are stars in there okay but anyways what we’re doing now is we’re opening up all of our lights so instead of just clicking on one and clicking open I want to first select them all so I’m going to click on one and then I’m going to press ctrl a to select all of my lights and then click open just to show you that it worked I can scroll through here and you can see they’re all highlighted meaning they’re all selected and if I click open you can see that it brings these all into a list right here like that now for some reason deep-sky stacker when you bring in this first batch of lights it doesn’t select them all the reason it does this I think is because what deep-sky stacker expects you to do is to go through your lights one by one perhaps and check the ones that you want to use if you’ve already checked your light frames in a different program like I did an Adobe bridge you don’t have to do this process and you could just go over here on the left hand side and click check all to check all your light frames so you can see I now have 392 checked I did leave in a bad light frame here just to show you what the process might be like if you were manually checking these in deep sky stacker so this second one I know is a fairly good light frame and if I just move my mouse over a star sorry it’s a little bit tricky with the trackpad okay there we go so if you look over here in the left hand side this is a 100% zoomed in view and you can see the Stars a little bit alveolar a little bit egg-shaped that’s okay I don’t expect this to be perfect but that’s that’s a fairly round star right and if I look at a few more stars trying to find a big one here yeah that one is nice and round so that looks like a good frame and if I just click on another random frame here and look at that same big star again it’s a little bit off but fairly round that one looks pretty round right okay so all of these frames are looking pretty good so far but now let me show you a bad frame to show you what that would look like and it’s this first one here I left it in purposefully if I move my mouse over this you can see that star looks quite weird it looks sort of pulled up and then if I look at another one the same thing if I look at yet another one same thing another one same thing they all have this left-to-right double pattern and the reason this happens is well there’s lots of reasons it can happen the reason I think it happened not here is because I was probably still walking around the Mount when I was leaving after I had set it up to take a bunch of exposures and because the ground was wet the mouth shake shook a little bit and that gave me these double stars so I don’t want to use this frame in my final result because it might just leave a little trace of that double star so what I want to do is I want to remove it from the list the easiest way to do this is just to right-click on it and choose remove from list and you can see our total number of light frames went down from 392 down to 391 and so you could do this just moving through for each frame and examine them all if you have another program that you prefer you can do it in there and then just bring all bring in the ones that you know are good I’ll also mention really quickly here that it does also have this thing up here which lets you brighten up the picture just like that it’s marginally useful when you have this much light pollution because we still can’t really see any kind of deep sky object but I just let you know that that’s a that’s a temporary stretch of your image so it doesn’t do anything to the final image it’s just for you to view right here okay that’s enough about lights I’m going to leave all of those checked and then we’re going to go over here back to the left-hand side and open up our dark files and we’ll go into our m101 folder click on the first dark press ctrl-a to select them all open them up dark frames it doesn’t deep sky stack doesn’t think that any of those are going to be bad or that there’s any real reason to examine them so it immediately checks them all so you can see as soon as I brought those in it brought in all 30 same thing with the other calibration frames so I’ll bring in my flats here and I didn’t do dark flats because these flat frames if we scroll down to the flats and then scroll over you can see that there’s a lot of cool information here actually these flat frames are only 125th of a second and because they’re only 125th of a second that’s not much time for dark current to build up also called thermal noise and so they’re usually the only reason to do dark flat frames is if you’re having a problem with biased calibration or if your flats are particularly long like 10 or 20 seconds and you’re worried about thermal noise in them but with such short exposures I’m not too worried about thermal noise and so I’m going to not use dark flats but we are going to use bias so I’m going to click on the bias files here make sure I’m in my biases folder and click on the first one press ctrl-a to select all and click open and I shot 50 bias frames mostly just because they are so short to take if you are at all unsure about which are your bias frames in which are your dark frames another thing you could do is you could just open up all of your pictures and then sort of go through here and find okay well here’s all my bias frames they’re one a thousands of a second there’s my flat frames there are 125th of a second and there’s my dark frames because they’re 30 seconds to match my lights so you can use deep sky stacker to figure out which files are which and then just reload them in as darks flats and bias if you were if you and already organized them as such just wanted to show you that exposure column just in case it’s useful the other thing I can check here is that everything is the same ISO if I scroll up to bottom to bottom the top yep everything is at ISO 800 which is good all right this point if I were doing this live with people I probably asked if there are any questions but if I’ve missed anything I always just asked me in the comments because I you know I’m doing this live but I it’s hard without an audience okay so we have everything loaded up here everything is checked I know that because it has these numbers right here so for instance if I click uncheck all you can see they all reset to zero if I click check all then we have them all except for the dart flats which we didn’t take so that’s what you want to see before we move on to the next step which is we want to click on this register checked pictures okay and basically in deep-sky stacker I use the defaults for the most part I find that the defaults work pretty well for most kinds of pictures and really the only reason to move off the recommended settings is if you are a more advanced user who knows a bit more about extra photography and aren’t getting the results you want I’ll just show you a couple things here though if you some of these things might be if you run into problems so the first thing is if you are running into problems a lot of times it’s because you you’re having trouble with registering your pictures together and a lot of that comes down to this star to track detection threshold what this basically means I think it starts usually at 15% or so is it’s the detection threshold is how big a star it’s going to look at before it counts it as a star so if we move this to the left and we lower the threshold then it’s going to let in smaller star but at a certain point it might be confusing a star with a hot pixel or other random noise in your picture and so if we click that you can see at 7% it’s can it’s finding four hundred and five stars if we bring it up to 65% now it’s only finding 32 stars so what is the right number of stars to avoid it latching on to noise it’s hard to say exactly it really just depends on so many factors but what I usually do is I try to look for a threshold where it’s finding a few hundred stars a couple hundred maybe between 200 and 300 stars of course this really depends a lot on focal lengths so if you are doing Milky Way shots or something like that it might find thousands of stars and that could be perfectly normal so don’t let the exact number of stars be your guide really it’s just you might need to change this threshold if you’re having problems with registration usually there’s no reason to change it off of the default unless you’re running into issues okay next thing here is where it says stack after registering I think that starts off unchecked but I usually just go ahead and check it that means that we’re just going to get through everything right now the other option is if you uncheck it you could just register your pictures then deep-sky stacker applies a score to every picture and then you could use the best picture to do to re-register and and stack and everything I just don’t find it particularly necessary with this kind of thing so I’m going to go ahead and click stack after registering and where it says select the best percentage of pictures you can set this to whatever you want so if you’re not sure about you know the quality of your pictures you might want to set it lower I’m fairly sure that these are fairly consistent so I’m gonna set it higher I’m gonna set it to 95% meaning that the worst 5% in terms of the stars being out of round it’s going to throw out before it stacks them all together next thing we can do here is there’s two buttons down here there’s recommended settings and basically all you want to do here is make sure that’s not throwing any big errors at you if there if it was throwing any big errors it would they would show up in red and then there’s stacking parameters and this is where it gets a lot more advanced but the good thing is again the defaults in deep sky stacker are quite good so there’s really no reason to change any of these unless you really want to basically what just a straight I’ll just explain quickly what a stacking mode is a straight average would mean that it doesn’t do any weighting it just it just looks at every picture is equal and and stacks them all together a Kappa Sigma clipping is it does a distribution and it looks at things that are outliers and it would throw outliers out and you really want this on especially if you are imaging from a city because you’re going to get a lot of satellite trails a lot of plane trails different things in your pictures if you just do a straight average those will those will show up in the final stack faintly if you do Kappa Sigma clipping those will disappear because it will throw out those pixel values and outliers okay I hope that makes sense for a result we just want the standard mode that’s what you want when you’re stacking a bunch of pictures together into one master exposure mosaic and intersection mode are if you are trying to make a mosaic of the sky so basically you’re you’re moving a camera all over the sky I tried to make one bigger field of view that’s not what we’re doing so we’re gonna leave it on standard mode you can only these drizzle options are very interesting and they do seem and you know like we would want this because the galaxy is going to be very small on our sensor but unfortunately because we didn’t have a mount that we didn’t do Auto guiding with dithering we can’t use drizzle that really only applies if you are differing meaning moving the the field a little bit between every frame otherwise drizzle doesn’t work okay I’ll click OK everything is fine here so I’m going to click OK again it gives me a final check here this is just a screen that explains everything it does explain down here that this process will temporarily use 53.9 gigabytes of on the D Drive so that’s what I was concerned about with with having that temp folder on the C Drive because I’m not sure if I even have fifty three gigabytes available and if you don’t have that amount available then the process will fail it tells me that my total exposure in terms of lights is three hours 15 minutes so it with 391 light frames at 30 seconds each that’s our total exposure time and that’s it we can go ahead and click OK it now starts off the process and I will mention here that right now you can see the first thing it does is it says adding offset frame what that means in deep sky stacker speak is it’s putting all of the bias frames together into a master bias I no mention here that right down here it says estimated time remaining time 1 minute 52 seconds that is not the total remaining time that’s just the total remaining time in this step which is just the first step in many steps it has to do to make our final picture because it has to first add together all of the calibration frames to make master liberation frames that uses those master calibration frames to calibrate the lights it then registers all the lights and then finally it stacks all the lights and some of these steps will take a lot longer than others but I expect this whole process to take hours considering we’re stacking 391 lights so I’m just gonna leave this what I would suggest is make sure you’re plugged into AC power and just leave it overnight or if you’re going to work you know leave it going during the work day and then you can pick it up in the evening I’m gonna stop the video here and pick it back up when this is all done okay it’s now finished stacking and we do get a little preview here and there is the ability to alter that preview and even save these changes that you make in deep sky stat hurt I don’t recommend actually using these histogram sliders or these different tabs here because it’s pretty coarse and a little bit hard to use these adjustments and you’re gonna get much better results in GIMP or Photoshop or any other program that’s better for the post-processing what we can see here though I’m just going to use two fingers on my trackpad there we go or if you have a mouse with a wheel a scroll wheel you can use that that we do see the galaxy now so remember in our individual lights we couldn’t really see it now we can see the spiral arms right there but we’re gonna bring it out a lot more when we do post-processing the one other thing I want to note here before we move on to saving is if we look at this this is the linear response of the channels and for some reason the blue Channel looks a most stretched already I’m not sure why that is it’s not it’s probably has something to do with my light pollution here but it’s something to be aware of this is a very linear response when this is when the spike is like very up and down like that and this is a more nonlinear response when it’s when it’s stretched out like that so I’m not sure why that happened but it’s something may impact our processing and photoshop so for instance I might immediately stretch the green and the red to more match the blue before doing more stretching hope that makes sense you will see if it doesn’t make sense you’ll see in the post-processing what I’m talking about okay the only thing we have to do now is save it does create an autosave that is a 32-bit file since in previous videos I’ve uploaded the 32-bit file has been causing some issues for people it’s really no big deal let’s just I’ll show you how to save a 16-bit file that’s in this raw state and it’s really easy you just go over here to the processing window you just go over here on the left hand side to where it says processing there’s a little blue box and the final option is save picture to file go ahead and click on that okay the default option here is TIFF image 16 bits per channel which is exactly what we want it also should be the default option that down here it says embed adjustments in the saved image but do not apply them and you want to leave that checked we don’t want this apply adjustments to the save image because then anything that we did down here for preview purposes would actually get applied to the image permanently and you can’t reverse it what we want to do is just get this images in its raw state and bring that into our next program for a compression I’m just going to leave it on none I’m gonna go ahead and call this m101 - DSS and I’ll save it to the desktop that’s fine okay it’s done saving and just to check here I can double click it and when it pulls up in the default photos viewer it should look mostly black that is what we want to see if you see a very bright image here something may have gone wrong with your processing all right I’ve moved back to my Mac here and we have the output file from deep sky stacker right here on the desktop this was the 16-bit TIFF file that we saved out of deep sky stacker so now I’m just gonna go ahead and open up the good new image manipulation program or a gimp I’m using a pretty recent version here which is version 2 point 10 I would recommend updating if you have an older version because only in recent versions that they add full 16-bit support for images which is what you need for astrophotography let’s go ahead and open up our TIFF image that’s on the desktop here it opens up in this central window just a few tips for navigating to zoom in use the plus button and usually on most keyboards the plus and equals button it shares a button so you have to hold down the shift key while pressing the equals key to actually use plus and then the minus key will bring you back out so that’s how we zoom in and out we can see it’s a mostly dark image with just some star cores here that’s what we expect the first thing action that I’m going to do is I’m going to go ahead and go over here to the layers panel the layers panel is in the lower right and I’m going to duplicate this layer I always like to initially duplicate the layer so I can always go back to the initial one if I need it the way to duplicate is you can just right click and choose duplicate layer from the contextual menu or you can go up to the layer menu at the top of your screen and choose duplicate layer from there once it’s duplicated I’m gonna go ahead and rename the layer by just double clicking and typing in a new name I’m gonna call it first stretch once with that done and first the first stretch layer selected we’re going to work on some levels meaning stretching the image using the levels come but before I open up that I’m gonna first look at my histogram here and you should if you are on a recent version see the histogram up here in the very sort of upper right area if you don’t see it go to windows dockable dialogs and just choose histogram and it should pop up over there and what I want with this histogram is to be able to see the red green and blue channels and so if you go up here to where it says value and go down to RGB you should now see red green and blue channels appear right here and one of the issues with this image probably due to the heavy light pollution is that the red green and blue channels are quite separated and the blue channel is like way over here like right along the left edge in the almost being clipped while the green and red channels look a lot more healthy so we’re gonna try to correct that a little bit in the levels command but it’s helpful to see the histogram here as we’re working and I’ll also note if if your histogram looks like that because this this area of the screen is way pushed over to the right go ahead and just grab this little three dots right here and stretch this over so that we can really fully see this histogram because right now actually during the stretching being able to see the histogram is actually more important than being able to see the image so it’s fine to shrink the image down a little bit so we can more clearly see the histogram anyways let’s go ahead and open up the levels command it’s under the colors menu so we go up to colors and then choose levels and just like in this histogram panel under channel we can go we can use value if we want to just stretch the entire image but I’m going to be actually working on the red green and blue channels separately and so the first thing that I’m gonna do is I’m gonna try to stretch out the red and the green and get them fairly evened out and then we’ll work on the blue last so this is going to be an iterative process meaning that we’re going to do it multiple times it’s very difficult especially with such a crude display to get it right the first time so we have to do it a few times to stretch out the image and the way I’m going to do this is I’m going to take the mid-tone slider here and move it into the left and take the shadow slider here and move that to the right and then hit okay so each time I bring up the levels command I have to reach use the the channel that I want to work with and basically I’m going to do the same thing that I did before which is stretch out that red channel of it and we’ll do this a few more times okay now that the red is sufficiently stretched I’m going to do the same thing to the green yin and it’s just again just something we are going to keep working on remember each time go up here to channel and select the channel that you want to be stretching okay at this point I’m going to try to bring the blue a little bit off of this left side to better match the green and the red so I’m going to go to colors levels and this time pick blue okay and at this point it can be useful to zoom in a little bit so we can see the the galaxy that we’re working on right now because there’s this heavy light pollution cloak it’s a little bit hard to get an idea of the color balance just from this but it can still just be fun to sort of see it come out as we’re doing this stretching so I’m gonna try to do a little bit more balancing here again just with this color levels command so I’m going to bring up the blue just a little bit more so it’s now at least overlapping with the red and the green we can see that the blue is a lot more stretched out which is why the background is completely blue here so we want to stretch out the green and the red a little bit more so let’s go to colors levels again bring up the red okay that was obviously too much because I brought that red peak way over to the left side so that’s not what I wanted to do I’m gonna go ahead and undo that so I’m just gonna do edit undo levels let me try that again it was a little bit too aggressive there so let’s do colors levels again choose red and I’m just going to do a smaller move this time and the reason I’m just doing this very gradually and then waiting is because the histogram display doesn’t update immediately because it’s based it’s basing it on the preview so basically I make a move here it has to send that information to the image and then it and then the histogram display over here changes based on what it’s seeing in the preview so basically what I’m doing is I’m just trying to sort of line up the black points of the blue and the red over here okay that’s good I’m going to go ahead and click OK and now we’ll go back into colors levels and try to deal with this green Channel and basically and basically the green channel needs to be stretched out some more so I’m going to use both of these I’m going to use both of these sliders both the shadows and the mid-tones and just sort of watch it over here that’s looking better maybe just a little bit more of this one now okay that’s fine I’m gonna go ahead and hit OK and now we’re really to the point where doing any more stretching at this point might be countering productive because we can’t really see the true color of the image because we’ve brought out the light pollution gradients so much both the vignette another system but then also this crazy color is just all the local light pollution gradients that we need to subtract that before we can really get a true sense of this histogram so to subtract it we first need a version of the image that is free of the both the galaxies and all the stars and this is a basically just a model of the background and to create that model I’m going to go ahead and duplicate this layer again so gonna duplicate the first stretch layer again the way we can duplicate a layer is by right-clicking on it and choosing duplicate layer from the contextual menu or you can go up to the layer menu and choose duplicate layer from there and I’ll be they call this duplicated layer background and to this background layer we want to basically do some processing on it to remove all the stars in the galaxy but leave behind this just sort of general gradient of the background so I’m going to start by going up to the filters menu and under filters there’s different categories here and go ahead and choose the enhance and then choose D speckle and what I’m going to do in D speckle is I’m going to raise the radius to the highest it will go which is 30 and watch what happens when I do that I’m actually going to go to an area of the picture with more stars okay so here it is at the default value and then if I raise it to 30 you can see even the bigger star cores all sort of disappear I’m gonna go ahead and hit OK okay and that takes out a lot of the bright stuff in our image too we might want to just try running it again let’s see if that works I’m not sure if it is we can just try repeat d speckle from the filters menu didn’t seem to do much so we’re still gonna have to deal with these smudgy high-level bits here go to filters choose blur and then Gaussian blur and again the default size of the blur will be insufficient for this job so let’s go ahead and raise it way up so I’m just going to enter something in here let’s just try 200 okay so I’m just looking at the preview here and with the Gaussian blur set to 200 it seemed to have taken care of all of those smudges left both the the pinwheel galaxy smudge and all the little left over star halos so that looks good to me again just play around with this until it looks right for your image I’m gonna go ahead and hit OK and now we have if we turn the visibility of the background off and on what we should see is that we basically just have this blurred background model that perfectly reflects the color and intensity of our actual image the first stretch image and so now what I’m going to do is I’m going to actually I’m gonna duplicate the first stretch again just in case anything goes wrong here so I’m gonna go right click duplicate layer I’ll call this duplicated layer BG for background removed okay and now what I’m gonna do is I’m going to take the background layer here and we’re going to apply it down to the BG removed layer using the mode command so basically every layer in the layers panel has a mode applied to it and usually we have the normal mode applied which means we’re only seeing the background layer here because it’s on top of our layers in the layers panel but if we want to subtract from if we want to subtract the background from the layer below we can choose a different mode here we want to choose the subtract mode so we just open that up come on and go down into the list and choose subtract okay and you should immediately see the image instantly sort of looks a lot more like a deep sky image as you’d expect let’s zoom in here though and just take a look at the pinwheel galaxy and because one thing that we don’t want to do is take away too much of the image at this point meaning clipping to black because you can see that the the sky is very dark here when we use the subtract mode so I’m going to change the opacity a little bit of this background layer so you can see mode is set to subtract opacity right now is set to a hundred and I’m just going to go down one percentage point at a time until I can see that I’m not losing any detail in the galaxy and so you can see as I doing this a lot of the the detail of the spiral arms are coming out and so I’ll just go back up to a hundred okay and you can see a lot of that faint detail in the arms is just clipped into the black background but if we go down to I think we were down to eighty now a lot of that detail comes back so at this point even though we’re trying to subtract the background model we don’t want to do so in a way that is destructive to the image let me zoom out a little bit here the only downside to the way that we’re working now is that because we’re only subtracting the background model at 80 percent we’re still left with a number of gradients the truth though is I was never expecting to use the entire field for this image so I’m going to crop to a much smaller area anyways because I just think that will highlight the Pitts the pinwheel galaxy in this larger field I feel like it gets a little bit lost as our main object and since I’m into this for mostly artistic reasons and don’t really feel the need to preserve the entire field I’m just gonna crop down and so I’m not gonna worry that we still have a bit of a gradient on the edge here if that is a worry to you though you could subtract it a hundred percent and then just try to deal with the clipping other ways but I’m just gonna try to get the most out of the galaxy and do that by clipping or by cropping away a lot of the field okay anyways so that’s now set this is what the picture looks like now just to clean up the layers panel a little bit though I’m going to merge this layer down into the one below it and you can do that by right-clicking on that layer and choosing merge down I believe that’s also available yes that’s also available in the layers menu up here merge down and then the BG just becomes a part of the BG removed layer below it okay so now we have first stretch which looked like that and we have background removed which looks like this the next thing that I’m going to do is I’m going to crop and so let’s zoom in here a little bit with shift plus or shift equals to make the plus sign and I’m just going to find the parts of the picture that I want to keep and so there’s some cool things in this field one is there’s a little John Galaxy right there that I definitely want to keep there’s also an irregular galaxy up here in that corner so I’m going to use those two as my sort of like corners of the image and make sure that I am including those when I crop okay so I’m going to open up the crop tool which is over here in the tools panel it’s the third row down four over from the left and I’m just gonna do a free crop that includes both of those features that I mentioned something like that and you can see that by cropping down to this we now have a fairly uniform sort of blueish background okay I mean I hit return or enter to accept the crop and we’re well on our way so now the issue if we look over at the histogram is that the blue channel is way out here and the green and red are are more in line so we’re gonna maybe dial back the blue a little bit or stretch the green and the red to even these out a little bit which will give us more natural color here so let’s open up that colors levels command but again and I’ll bring up the the blue channel here and I’m just going to bring in the shadows slider a little bit something like that and actually since we’re sort of working on all the colors right now I can actually I don’t have to close I don’t have to hit okay yet I can I can make that adjustment to the blue and then switch right over to the red so I’m gonna do that and I’m gonna bring up the red channel a little bit something like that and at this point it actually can be useful to look at our image as we’re doing this I mean is oom in a little bit or maybe not okay I’ll zoom in next time so this is actually looking really good the only thing that I might want to do is just bring the level the red over just a tiny bit more too much there we go okay I’m gonna hit okay now let’s go ahead and zoom in okay and we still have just a little bit of an uneven background but let’s see if that matters as much once we do a few more steps here the next thing I’m gonna do is I’m going to make a luminance layer and basically what I mean by that is a layer with it is devoid of all saturation devoid of all color and we’re gonna use that luminance layer as a mask as we get going here so let’s go ahead and create it the first thing we’re gonna do is we’re going to duplicate the BG removed layer so I’m going to right click and choose duplicate layer I’ll rename this luminance I’m going to go to colors desaturate and choose mono mixer and basically this lets you change a color image into a mono image or a luminance image and it lets you change the red green and blue channel mix if you want to so I’m just going to play around with this a little bit that looks fine and hit okay and now with this black and white image I’m going to stretch it in such a way that the stars and the galaxies really stand out real are really white and the background is quite black we’re going to try to make it really dramatic because that’s what we want for a mask so we’re going to use the colors option again this time I’m going to use curves and we’re basically just going to apply what’s known as an s-curve here okay and again this is an area where I feel that doing it in a few steps is useful so I always start by putting a point down here in the shadows area and then do something with the this one up here and basically what I’m trying to do is just make the stars and the galaxies quite bright in the image so that eventually we can just knock the the background down to black like that okay maybe one more okay I’m gonna call that good so basically we’ve just made a very black and white mask where it’s protecting the stars and the galaxies but excluding all of the background information and what I’m gonna do with this now is I’m going to make a new version of the BG removed layer so I’m going to go ahead and duplicate it again and I’m going to call this saturate and I’ll make another version of that so duplicate it once again and call that desaturate and so basically i want to saturate the galaxy and the stars and desaturate to the background and with both of these we need to apply the luminance mask to them before we do our work on them okay then I’m going to right-click on the saturate layer and choose add layer mask we can just start it with white that’s fine then I’m going to go up here to my luminance layer and select it so do select all copy it to the clipboard so you can either just do copy or copy visible either one will work okay I’ve added a layer mask here I’m gonna go ahead and choose that we want to edit the layer mask so make sure that work on the layer mask is X trite there then go ahead and paste so you can do edit paste or command V on Mac control V on Windows for whatever reason this is the way GIMP works instead of just pasting it right in to the layer mask it puts it as a floating selection which you can then do different things with but we want to anchor it into the layer below it was in this case into the layer mask because that’s what we last selected so just going to hit the inker button right there and now you can see that it’s been put into the layer mask just to double-check that what we can do is we can right click on it and click show layer mask and we can see yes indeed our layer mask is now the same as our luminance layer okay now we’re going to do the same thing for the desaturate layer except we want a inverted luminance mask so let’s go ahead and turn the luminance mask back on and duplicate it and I’ll just rename this inverted lum and then let’s go ahead and go up to the colors menu and choose invert it does a straight inversion of the black and whites which is what we want since we really want to protect the galaxy here I’m also going to apply a threshold to this inverted loom meaning that it’s going to become even more black and white not just this sort of shade of grey here so I’m going to go up to the colors menu and go down to threshold and then raise the middle slider over here to the right until that galaxy part is completely filled in hit OK okay now let’s go ahead and copy this to the clipboard so I’ll do select all edit copy I can go ahead and turn off the inverted loom and the luminance turn on the desaturate layer go ahead and add a layer mask to that layer control click or right click and choose add layer mask doesn’t matter what we put in at this point go ahead and then select that layer mask so just make sure that you have edit layer mask clicked there and then let’s go ahead and paste okay let’s pay and then again just like we did last time anchor that floating selection down into the mask and then just if you want to be sure that it actually is there just click right click and choose show layer mask and we can see yes it is there okay so I’m gonna turn off show layer mask click on the actual image here the desaturate layer and i’m going to go ahead and do what the layer says we’re gonna desaturate the background and also darken it a little bit so let’s go ahead and go up to the colors menu again choose saturation nope go to the colors menu again choose hue - saturation and I’m gonna bring down the saturation and also bring down the lightness okay and then on my saturate layer I’m gonna do the opposite so I’m going to go ahead and go up to that colors menu choose hue/saturation and bring up the lightness and bring up the saturation okay if we look at our galaxy again we can see that we’re getting some blue color in there it’s a little bit faded still so one thing we may want to do is actually just duplicate this saturate layer that will bring it up even a little bit more and I can duplicate the desaturate layer too and let’s just look at our RGB histogram again it’s looking pretty good one thing I’m noticing is that the picture has a little bit of a green cast to it so one thing we might want to do at this point is make a new from visible layer so under the layer menu there’s an option to make a new layer from what’s visible and it just makes a new layer over here that just is called visible and I’m just going to try to in this layer balance the colors a little bit better zoom in on the galaxy so you can see that we have some blue and yellow look to it but which is what we want but it’s also a little bit too green in general so I’m going to again go to that colors open up color balance and let’s just try adding a little bit of magenta to the image a little bit less green and I think that immediately improves it quite a bit it’s a little too far you can also play around with the cyan red command here I think that definitely improved the star color quite a bit by adding a little bit more red and you can do the blue yellow so right now we’re working on these color levels in the mid-tones but we might need a fully different option for the highlights and the shadows so I’m going to go ahead and click OK on that and go ahead and zoom out back a little bit this is looking really nice I think in terms of colors but really what I want to do at this point is is bring down the the background level quite a bit so I’m going to use that that desaturate layer mask let’s just go ahead and duplicate this visible layer and I’m just going to call this black point correction I’ll go ahead and add a layer mask to that and I’ll turn back on my inverted luma here and let’s just copy that turn it back off click on my black point correction ask press command-v or control V on Windows and then anchor that down into there okay so we now have the inverted loom as the mask on the black point correction meaning it’s not going to bring down the color of the galaxy or the Stars okay and then I just have to click on away from the mask onto the actual image because now we want to actually make an adjustment to the image but with that mask applied so it’s click on the image one little way to know which one your clicked on I mean it makes this white box around it but the other thing to keep in mind is that the if your clicked on a mask you’ll see that there’s a green border around the image and if you clicked on the actual image then there’s a yellow border so we want the yellow border then I’m going to go up to the colors menu and go down to curves and I’m just going to reset the black point just like that by just bringing it over and you don’t want to go too far with this I know that might look better to some but it makes it makes the image look a little bit I think fake so we really want to be careful here with how far we go with this something like that is better than just bringing it really into the clipped black area okay and there’s not too much more I want to do with this the one thing that is bothering me a little bit is just that if we look up here I don’t know if you can see this because it’s pretty subtle but there’s this dark area right here that it’s a little bit darker than the rest of the sky what I think happened is there is a dust mote that didn’t get corrected by the flaps and so I just want to bring up the values in that area a little bit okay so what I’m gonna do is I’m gonna create a new visible layer so a new foam visible again so now we have visible number one here I’m just going to rename this touch up and I’m going to add a layer mask to that so just right-click and add layer mask I want it to be black okay so now we have a black layer mask on there the layer mask is selected now I’m going to choose a brush the paint brush tool I’m going to change the color of that brush to white let me use a 0% hardness and the rest is fine I’m just going to adjust the size until it sort of matches that that’s streak I see and then I’m just going to draw out a line on there and if we want to look at it we can show the layer mask there it is turn it back off and that basically that line just basically matched where I saw that it was a little bit darker in the background because of that artifact now I’ll click now actually I’ll zoom out so you can see the whole image again basically and now I’ll click back onto the actual image here and go to colors curves and I basically just want to brighten up that area of the image just a little bit so I’m just going to grab the curves and you can see if I go too far then it’s then it’s quite obvious what I’m doing but if I just brighten it just a little bit like that then it just sort of evens that area out and one thing that I’m noticing is that I didn’t quite cover the whole streak with my first brushstroke so I can leave this curves on but now just click back on the layer mask bring up the paint brush again and just try to paint that in a little bit more until it looks good all right that looks good so I think we are about done here this is our final image out of the new image manipulation program hopefully you can see that we do have some star color here we do have some color in the galaxy of course this is a fairly noisy image which is to be expected shooting from Bortle 9 but I think a lot of people might still be happy with this given the conditions so final step out of the new image manipulation program is to save it and so if you want to return to it and keep editing it here in GIMP you can do save as and save it in the native format so I was can just call it M 101 dot x CF click Save and then that will keep all the layers information if I want to come back and try fixing something or changing something I can come back in and just you know delete a layer try again that kind of thing ok then I’m just going to do file export and this is how you save anything other than the gimp file format so if the default is PNG but if I want to do JPEG I can just switch it up there to jpg and it’ll save it as a JPEG instead it gives me some options I’m just gonna do a hundred percent quality click export okay there’s our final image out of GIMP the one thing I might I really like how the stars came out in this one the one thing that I might do a little bit differently is I think the way that I did the layer masks we got a little bit too much noise in the the galaxy I think when I when I use that threshold command the one layer mask it made this a little bit too standoffish even though it does really stand out this way so I might change that a little bit but overall pretty happy with it give in just an hour of work in GIMP if you have any questions or suggestions please leave them in the comments and if you stick around here for a second you’ll see all of the people supporting me on patreon I’ve been getting a lot of new people in that community and I really appreciate all the support till next time this is Nico Carver from nebulaphotos.com. Clear skies! .