Stacking for Noise Reduction in Starry Landscape Stacker (Better Than Sequator?)

your low light astrophotographs will undoubtedly have noise in them and that noise is randomly distributed so if you capture multiple exposures of the exact same scene same composition same settings the noise in each of those images is going to be randomly distributed so what that means is if you create an average of all of those images you capture the random noise gets removed in the averaging process but the scene which stays constant will begin to shine through in much better detail as you lift that veil of noise now of course the problem with capturing a scene which has a foreground and a Starry Sky Is that the Stars will move between each frame so if you average those images without doing anything first you're going to remove the stars in the averaging process so you actually have to stack the foreground first and then you stack the sky separately and before you stack this guy you have to align all of the stars in those images before you stack them and if that sounds complicated don't worry there's software that will do all of the hard work for you I've already created a tutorial video about sequitol which is a free windows program that does all of this for you but if you're a Mac User the best current option is a piece of software called Starry landscape stacker which currently costs about 40 bucks so in today's video I'm going to run through a demo of Starry landscape stacker and then we can compare it to sequitur and see which one does a better job so I've got these 16 exposures here captured with a 35 millimeter lens at F 2.8 10 seconds ISO 6400 and if I just lift the exposure and zoom into 100 you can see there's a lot of noise because it's a very short exposure and if I flick through all of the images you'll see that there's also a light moving through the frame there's a person or persons walking through the frame so it'll be interesting to see what happens to those in the stacking process but before I start I'm going to do some basic adjustments because I want to see what I'm doing um in the software so I might lift the Shadows a little bit don't need to lift them too much because of my snowy foreground is quite bright um let me drop the highlights a little bit just some very basic adjustments to flatten the image and see what I'm working with and also the lens correction so come on the lens correction enable profile correction and remove chromatic aberration in the detail tab I'm actually going to remove the sharpening because if I zoom in um you'll see that it's actually sharpening the noise that's in the image so I want to remove the sharpening and I'll sharpen the image after I've done the stacking and remove the noise I'm going to come back to the basic Tab and fix the white balance so you can see that there's a quite an off balance between the blues and the yellows but just by looking at the histogram so I'm going to click on the number here and slide to the left and right and you can see that's more of a correct white balance and I'm going to do the same for the tint now you can see there's a much better balance between the colors so this is a more correct white balance but I'm actually going to shift it slightly Into the Blue fuse because I want to take a bit of artistic license with this image because it was very cold and I want to have those cold blue tones so and then once I've made the edits to one image I'm going to select them all in the film strip down here or you can press Ctrl or command and a and uh just sync all the settings so I'm going to press the sync down here um check all if you haven't already and then synchronize if I come back to the grid view by pressing G we can see that the settings have been applied to all of the images and now what I could do is right by this click come to export and then I actually have a preset called stack I'm just going to show you guys what's going on here so I'm going to come to file export and I'm going to choose my stack preset so what this is doing is exporting to the desktop in a subfolder and I can rename this to um snow beacons for example and there's a real need to rename the files they're not videos so I don't need to worry about that the file settings is a tiff no compression srgb and 16-bit in the bit depth make sure you're not resizing the images no sharpening metadata is up to you no need for a watermark and then after export so it's got open in other application and the application is from the applications folder Starry landscape stacker so basically what happens is as soon as I export the images will automatically open in Starry landscape stacker ready to be stacked so whilst we're waiting for that a quick message from the sponsors of today's video skillshare skillshare is an online learning community with people from over 150 countries come together to take the next step in their creative Journey there are classes on an enormous range of creative topics such as photography videography freelancing business graphic design and if you're enjoying this video I'm sure you'll enjoy Ian Norman's course on nightscapes it's an amazing crash course into the basics of landscape astrophotography I've been using skillshare for a few years now for a wide range of different things for learning Spanish because I quite often go to Spanish-speaking countries things about freelancing and business and even video geography and video editing so things that will improve my YouTube videos and it's also where I learned the skills to create the introduction to my Astro Vlogs which so many of you absolutely love if you would like to join along the first 1000 people to click the link in the video description down below will get a one month free trial of skillshare Premium which gives you access to all of the classes on skillshare there's no limit to how many you can try out in that month you can download them for offline use which I love doing just before I get on a flight and if you're enjoying skillshare an annual membership is surprisingly affordable so follow the link in the video description down below start a new hobby brush up on some skills maybe start your own business in 2023 and thanks skillshare for sponsoring today's video okay so the images have opened up in Starry landscape stack and you can see there's a bunch of red dots where it thinks the sky is now just for example purposes I'm going to put some red dots in the foreground if you see red dots in the foreground you can come here to to erase red dots and just get rid of those red dots in the foreground if I get rid of that one because that was very borderline and then you can just click on find Sky and you can see it's done a very good job of working out what sky wants foreground and it's a very difficult image because the exposure value and the color of the foreground in the sky are very similar so I'm just going to help it out by coming to the options here and selecting ground and just removing the selection of the sky from the foreground and you can actually be a lot neater with this so you can zoom in to actual pixels to 100 and holding the spacebar you can drag a lot better and I might take the sky brush here and just help it work out what sky and what's foreground I'm just going to come down here and yeah you can be a lot neater and take your time with this but for demonstration purposes um I'm just gonna do it very roughly Zoom to fit and then there's an align with tab which is optional this basically chooses the image where it lines up the Stars so the final image will look like the image you choose for Align with because it moves All of the Stars to that position so it's optional it usually chooses the image that's in the middle so that it moves some of them forwards and some of them backwards but if for example there's an image where the stars are lined up with the foreground in some particular way that you want you have to choose the image so for example I recently shot a time lapse of Orion above the Matterhorn and there was an image where it looked as if Orion was standing on the tip of the Matterhorn so I selected that image to make sure that all of the stars lined up to that image when I stack them then there's exclude images so if there's any images that have got like crazy lights in the foreground or you know a big plane or something I don't know you can exclude them but I just wouldn't export the images that I don't want so I don't need to worry about that and then you can come down to align and composite and just to align and composite and it does all of the alignment of the stars for you and blends it back onto the foreground which is amazing now you can see we've got much less noisy image there's a few different algorithms you can use mean minimum Horizon noise is the default and it's usually the one that produces the best results and if you hover your mouse it tells you what each one does maximum value for example chooses the brightest pixel of all of the images so the brightest corresponding pixel and so you can see with this mode the lights will actually appear from each of the exposures because that was the brightest pixel uh in all of the images but if we choose minimum value it chooses the darkest pixel of all of the images you can see it's a very dark image but normally the best one is mean minimum Horizon noise you can see that the the lights that were on the path have been removed in the averaging process and everything looks super good if I zoom into actual pixels just to check everything's okay you can see there's a a bit of an artifact here where the mask of the sky and the mask of the foreground meat so what I could do is go back into edit sky and using the sky brush I can just take that closer to the mountains and hopefully that'll fix up that little error and there you go there's a much smoother uh blend going on there so that looks a lot better so I'm just going to zoom back out and then you can save the current image if you want you can also save a copy with the mask the sky mask but Starry landscape stacker just doesn't produce the best Sky mask so I just wouldn't find this useful I'd much rather create my own Sky mask in Photoshop later if I needed it for whatever reason but you could just come to save current image and save the image wherever you like you could change the name if you like as well and just save the image as a tiff file so how many images should you stack like what's the optimum amount well the more images you stack the better noise performance you're gonna get but obviously there's going to be some issues the more you stack as well now the math tells us that the amount of noise performance improvements you get is equal to the square root of the amount of images you stack so if you stack four Images you get twice the amount of noise improvements over a single exposure if you stack nine images you get three times the amount of noise performance over a single exposure if you stack 16 images you get four times if you stack 25 images you get five times and if you stack 36 images you get six times the amount of noise improvements but if you try and stack too many images the stars are going to move too much and there's going to be an issue trying to blend that Sky back onto the foreground and there's also a point where you just start hitting diminishing returns so at the beginning going from like one exposure to two to four to six to eight you get a a great increase in the noise performance but as you start getting to 16 and 20 the improvements just start leveling off and you just start hitting diminishing returns so personally I'd recommend at least eight or nine images but for an Optimum amount I'd say it's about 15 to 16 but that's obviously going to change depending on your camera but as a Rough Guide I'd say at least eight and up to 16. so I can just show you some examples if we compare a single exposure to four Images stacked and we zoom in you can see there's a decent Improvement in the amount of noise that's been removed from the image if we compare four to nine so we've got four on the left and nine on the right you can see again there's a decent Improvement in the amount of noise that's been removed so especially in the background of the Sky starting to look a lot smoother a little bit more detail coming out then if we look at 9 versus 16 again it's quite a decent Improvement especially in the background Sky it's a lot smoother now and you know we're still seeing some decent improvements if we take a look at Andromeda in the image there it's a lot cleaner and less fuzzy and crunchy like it is in the nine image now if we look at 16 versus 25 I mean there's a slight Improvement in the amount of noise in the background sky but it's not as big of an improvement as the previous ones that we compared so you're having to take an extra nine images but you're not getting that much improvement in the noise and this is why I think 16 is a bit of a sweet spot for stacking because you're not taking so many images that the stars are moving so much against the foreground and again you know 16 images you have to take an extra nine to see this very small amount of noise improvements I mean there's no denying there is an improvement but it takes a long time um to see that Improvement if we compare 16 to 36 for example I mean yes it is noticeably cleaner especially in the background sky but considering you're taking 18 more images which if you're doing 30 second exposures that's an extra nine minutes just for a small increase in noise I feel like 16 is that sweet spot where you know you get the increase in noise performance and then you hit 16 and it starts flattening the curve so 16 for me is The Sweet Spot obviously the more the better until the Stars start moving too much relative to the to the foreground but how about the comparison between sequitol and Starry landscape stackers so I've got a good example here to show you so on the left is Starry landscape stacker and on the right is sequitur now it might not be obvious from this view but if I just zoom into the tree you'll notice with Starry landscape Stacker it just hasn't done a good job of masking this complex tree and so pretty much anything within the lengths of the tips has been considered as foreground and because of this there are no stars in the gaps between the leaves of this tree it just looks like a composite it just sticks out you know very very obviously but if you look at Secreto it's done a better job of getting in between those leaves and you know you can see a few Stars through the gaps in the leaves it hasn't done a perfect job by any stretch of the mark but it's definitely done a better job than Starry landscape stack and I'd say it's a lot more usable because you can see some of the Stars through those gaps in the trees so sequitol is definitely better than Starry landscape stacker and I've noticed this issue with sort of complex trees quite a few times now with Starry landscape stack and it's a shame because whenever there was a tree a complicated tree silhouette in my foreground I'd always utilize stacking because I knew sequitur would do a great job but I can't rely on Starry landscape stacker to do a great job and I wouldn't use my star tracker when there was a complicated tree in the foreground because you end up with like a super blurry tree in the foreground and um trying to blend that on to a foreground tree was it just absolute chaos it's it's impossible and so you have to move your tripod so that the tree is no longer blocking your view and take a clean exposure of the sky and blend that onto your tree foreground but because of the movement of the tripod that then makes your image a composite and I don't like doing composite images and now I feel like I'm gonna be forced into doing these sort of mild Composites because I can't rely on Starry landscape stacker to stack images when there's complex trees in the foreground however there is a workaround there's another piece of software which I'll talk about in the next post-processing video so make sure to hit subscribe if you haven't already and whilst you're here do check out some of my in the field videos some of my astral Vlogs and if you're going out to enjoy the night sky anytime soon I wish you good luck and clear skies

Channel: Alyn Wallace

Views: 37,538

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Id: mweQuwGpj3U

Length: 17min 27sec (1047 seconds)

Published: Sun Dec 18 2022