Planetary Imaging - Stacking with AutoStakkert!2

welcome to planetary imaging stacking with Auto stacker to more and more people are choosing Auto stackers for stacking their movie files of the planets Sun and Moon Auto stacker reads in the movie file stacks the frames and writes out a picture file of a single stacked image that stacked image can then be used by Reggie stacks or other software for image processing to make a much sharper picture running auto Stuckart we see we have two windows the window on the left has three buttons numbered one two and three it is easy to guess that pushing these buttons in sequence is the way to go the main roadblock is that the number three button is disabled after doing number one and two you need to select some align points using the window on the right to enable the number three button now you know enough to get started for the rest of this video I'll take you through some of the settings that I understand or think I understand remember that not everything you see in a YouTube video is true let's start with the drop-down menu items you should briefly go through them to at least be aware of what is there for some video files I have to use a force D Barre option under the color menu because the auto detect option chooses the wrong one on the advanced menu there is an experimental option it will bring up another window which has some instructions to hopefully explain what the features are before pushing button number one notice this limit frames text clicking on it brings up a small window which will allow you to cut out some frames at the beginning and/or end of the movie file you will normally not use this feature we push button number one and open our movie file now we see frame number one in the right window using the slider we can scroll through all the frames pushing the play button is useful to see how turbulent the sky was the planet is centered in the window even though it bounced around during capture if you have a moon off to the side you may not want the planet to be centered you can move the planet with the mouse while holding down the shift-key the offset will be displayed here you can reset the offset to zero by clicking on the displayed offset in addition to pushing button number one to open a file you can also drag a file from Windows Explorer to either window of Auto stacker Auto Stockert will do batch processing if you select more than one movie followed you can learn a lot by reading the tooltips that come up when you hover over parts of Auto stacker for example hovering over button number one gives us a tooltip that says you can also drag and drop files or folders with B&P TIFF fi t-- jpg or PNG images to this form in the right window we have these two sliders to control the amount of cropping we want auto stacker to do cropping is a good idea when you have large amounts of black sky surrounding a relatively small planet image Auto stacker will then run faster the text in the upper left corner of the picture can be turned on and off with this details check box just below button number 1 we have the image stabilization group Auto stacker has two different ways to detect image movement and we have to decide if we want to select surface or planet the planet option uses center gravity but usually only works on planets it will work on the Sun or moon if the field of view is large enough to fit it all in as long as you have dark sky surrounding it it should work you can use surface on planets but it will take longer the center gravity method appears to work in a split second notice how the planet is already stabilized when I select planet selecting surface and we are no longer stabilized stabilization has now been added to the list of things to do if you want to know how the center gravity thing works I've put a link in the video description to another video which shows how to calculate the center of mass for the planet image the pixel brightness is the mass and the calculation is done twice once for the horizontal and once for the vertical furthermore the pixel brightness is considered to be either zero or one otherwise bright spots on the planet such as a polar cap would count more than dark spots the brightness levels in the video file go from 0 to 255 a threshold is calculated say a brightness value of 20 and everything above that is counted as planet and everything below that is kinda sky if you uncheck dynamic background you can specify the threshold value yourself when using the surface option we get a green rectangle on our image you can change the size of it by pressing the 1 through 9 Keys when that window has focus just click on the top bar of the window to give it focus the idea is to select a distinct feature you can move the rectangle with control click a larger rectangle will mean longer computation select a feature near the center so we'll be more likely to be included in all the frames the tooltip for the improved track box says slower but sometimes more accurate tracking for jumpy recordings my guess is that the image in the rectangle is being slid around left/right up/down while comparing it to the next image to see where it matches the best when checking improved tracking the amount of sliding around is increased to allow finding the proper match when you have greater movement from frame to frame this can be due to a wobbly mount or low number of frames per second to be sure I get the best results I always check this box and just bite the bullet on computer time even though it possibly isn't necessary with the surface option were given this expand versus crop choice when recording a Sun or moon video the target will drift around during capture parts of the moon will appear in every frame and other parts will only appear in some of the frames if you choose expand then you'll end up with a larger image one that contains every part of the moon captured even the parts that were only caught in one frame if you choose crop then you'll end up with a smaller image but every part of the image will be stacking the same number of frames next down we have some options under the heading of quality estimator the purpose of estimating the quality of each frame is so we can sort them and then only stack the very best the reason the images don't all have the same quality is due primarily to atmospheric turbulence if we check the details checkbox we see that there is already a quality value assigned to each frame at least if gradient is selected remember that I did not write Auto stacker and I don't actually know how it calculates the quality estimate what I'm going to tell you is not how it works the actual algorithm is more complicated but this simple-minded method should be helpful for deciding which options to use bad seeing is a lot like bad focus the image becomes blurred and the contrast is decreased imagine you look at the brightness value of the pixels for just one row through the centre of the picture compare the brightness value of each pixel to the previous one add up all the changes taking the absolute value of the difference if the pixel brightness value is 5 more than the previous one that would count the same as if it was 5 less than the previous one perhaps to eliminate negative numbers you would square the difference and add up the square of all the changes the sum of all these changes will be higher when the seating is good bad seeing tends to make everything look the same and good seeing results in a more contrasting picture which has bright pixels next to less bright pixels this sum of differences then become a quality estimator which can be used for ranking all the frames when the gradient option is selected there is a noise robust value for us to choose hovering over it we get the message gradient quality estimator number represents scalar details but can easily be fooled by noise if set too low the noise robust value can be between 2 and 8 if your image is color and requiring debayer then the robust value can only be 4 or 6 with my simple-minded way of calculating the quality estimate we compare groups of pixels rather than individual pixels and this setting selects the size of the pixel group use a small noise robust value if you have a picture with little noise if you use max gain and your capture looks a bit noisy then use a higher value when planet CLG is selected for image stabilization then you can choose either edge or gradient for the quality estimator choose edge when part of the planets edge is not sharp due to being able to see the Terminator this is always the case for Mercury and Venus and possibly Mars when not at opposition you then need to check the regions that have the sharp edges in this picture of Venus we have sharp edges from here to here so we would check these boxes here and uncheck these presumably Auto stackert will then look for sharpness in these regions the frames that have poor quality won't have edges as sharp as the high quality frames when edge is not selected you then have this local versus global option when you select local then the quality will be assessed for each region associated with each align point and then will be sorted separately for example suppose we have 10,000 frames in our movie file want to stack the best 20% and that we select just for align points if we select local then Auto stackert will sort all 10,000 frames based on the quality of just the top left region and stack the best 20% it will then do the same for each other region at the end it will then create a mosaic from the four smaller images another way to say this is that Auto stacker considers your 10,000 frame movie file has four separate crop movie files each with 10,000 frames it ends up with four stacked images that are then stitched together to form a single mosaic the advantage of using the local options should be obvious when watching the movie play we notice ripples or waves of atmospheric turbulence part of the planet is sometimes sharp while the rest is not so for the Red Spot on Jupiter you want to sort the frames based on the quality around the red spot and likewise for each other part of the picture you should always use local the ability to select global is included in case you get some artifacts along the seams where the individual regions are stitched back together if that happens then it is most likely caused because you have aligned points that are too small so I will try fewer aligned points first to try to fix the problem to experiment with different quality estimator settings try using only the best 5% of the frames by using the best 5% you're more likely to see the effect of a quality estimator setting compared to using the best 50% for example after choosing the settings we want here in this region we press the number to analyze button and wait until we see done here now we move on to the settings that affect how the stacking is done the first one we come to is reference frame the reference frame is needed to calculate the x and y offset for each alignment point for each frame the offset changes from frame to frame due mostly to atmospheric turbulence but also because the center of gravity or surface image stabilization techniques are not perfect the first checkbox says last stack is reference but I can't check it the tooltip says it only works when stacking twice of course the next checkbox says auto size quality based if you uncheck this box you get an option to select the number of frames my guess is that auto stacker will combine this number of frames using only the center gravity or surface image stabilization technique for the purpose of making a reference frame it may be worth the effort of stacking twice so you can use the last stack as reference option to try and get a tad better stack I always leave this box checked this quality graph appears after doing the analyzed step there are two things plotted the quality of the frames as they were captured is shown in gray the quality of the frames after being sorted is shown in green the top slider on the preview window moves us to the frames as before but now the frames are sorted based on their quality estimate the text in the upper left shows us the frame number of the sorted frame and to the right it also tells us the frame number from the original capture note that you can move the slider one frame at a time with the arrow keys if you first click on the slider and also keep the mouse pointer over the slider control sometimes you'll see a bit of red along the bottom of the quality graph once I had half of my frames having zero quality this can happen if your movie file has duplicate frames Auto stackert will mark the quality of a duplicate frame at zero up here we see we can output our stacked image as the TIFF PNG or fi T file by selecting the radio button of our choice next we are presented with eight edit boxes to allow us to create multiple stacks for example if I enter 10 20 40 and 80 in the frame percentage boxes I'll get four stacked images the percentage will be reflected in the filenames or folder names where they are saved likewise you can enter the number of frames to stack in these boxes in the top row note that if you control click on the quality graph you will zero out all the boxes except the first one in the second row which will be given the value of the percentage of where you clicked simply clicking on the quality graph has different behavior you must hold down the ctrl key while clicking to get the frame percentage box to be changed how many frames should we stack what percentage of frames should we stacked I'll tell you my thinking at this time but please experiment for yourself the idea that I have found what is optimal is absurd Auto stacker it makes it easy to experiment by giving us these eight boxes I have noticed that if you stack 500 frames and also stack 5,000 frames that the two stacked images appear about the same before sharpening when applying weight of the sharpening there comes a point where further sharpening just makes it look worse you can apply much more sharpening with the 5000 frame stacked image before this happens so stacking 5,000 frames can be better than stacking 500 frames so where do you draw the line just looking at this quality graph you would want to select maybe 10% these 10% are better than all the rest and you don't want to throw in all these less perfect images it also depends on how quickly this green line drops if it stays fairly high into a way over here before dropping then that means you have a large percentage that are all about as good as the best of course if the green line drops much earlier then you only have a few that are about as good as the best I take all this into consideration I want to stack at least a thousand frames and preferably 2,000 to 4,000 or more with the quality graph like this I would select 95% of them if it was made with only 2000 frames if it was made with 20,000 frames then I would select 10% or 20% because auto stacker makes it easy to experiment I have found that sometimes it makes little difference if you stack 20% or 80% and other times 20% is much better than 80% and also the other way around recently I've noticed that Saturn prefers a higher stack percentage than other planets but that may be due to me capturing Saturn at a lower histogram setting so be alert to notice if the histogram of the capture affects how many frames to stack the normalized stock option exists when planet center gravity is selected I use it to give me a desired percent histogram I normally captured with a low histogram so I can get more frames the normalized stack option will brighten my stacked image be careful not to choose something too bright say 95 percent because you need some room for wavelet sharpening which increases your percent histogram using the normalized stack option will also ensure that all your stacks for an animation will be uniform in brightness I always use normalized stack the sharpen checkbox allows you to get an extra stacked image that has been slightly sharpened it will have the same file name but with underscore CO and V appended to it the reason this feature was added was to make it easy to find the best stacked image out of a group for example suppose you have ten movie files you would end up with ten stacked images now you want the best one but it's hard to tell which stacked image is best you pretty much have to process all of them to see how much detail is in each with the sharpen checkbox checked you end up with the same stack of images as before but also another ten that are partially sharpen hopefully you can now tell which is best and you will then go process the corresponding unsharpened one the sharpen images were not intended to be used for further sharpening many people do use the sharpen images though without any ill effect if you check sharpen you will get this blend raw in for X percent option I never use the sharpen feature but if I did I would select zero percent for the blend that way you get the full amount of sharpening I don't live in the desert so my images are never that sharp to begin with a little bit of sharpening the auto snacker gives when this option is selected is never too much if it becomes too much then you can reduce the amount of sharpening you end up with by blending back in a proportion of the unsharpened image this may not be what the blend option was intended for or how it works but that is how I view it next we have RGB align our G B stands for red green blue checking RGB align makes it so you don't need to waste a lot of time doing RGB align and Reggie stacks Auto stacker it's version of RGB line is also better it even aligns to sub pixel accuracy the reason your colors need to be aligned is because the atmosphere bends different colors different amounts without color alignment you'll end up with a blue tinge on one side of the planet and an orange tinge on the other Auto stacker gives us some control over the output file names the stacked files are saved in the same folder as the movie files or if you check saving folders then new folders are created in the same folder as the movie files checking saving folders will cause n folders to be made where n is the number of nonzero boxes here so it is possible to have up to eight new folders being made for example suppose I enter 2000 and 4000 for the number of frames that stack and also enter 10 20 and 50 for the frame percentage this tag then I would end up with these five new folders the output file name is the same as your movie file but of course with a different extension for example your movie file has avi but your stack image has ti f4 the file name extension in addition the output file name has information about the quality estimator and the number of align points if you select a gradient for the quality estimator then the output file name would include an underscore G along with the noise robust value if you selected edge for the quality estimator then you would get an underscore e followed by eight zeros or ones which represent which of the eight edge checks boxes were checked for example suppose I use this I would get e underscore one zero zero zero 1 1 1 1 as part of the file name it appears that it starts at the top and goes clockwise with one representing the check boxes and zero the uncheck boxes the file name also ends with underscore ap X where X is the number of align points if you don't select save and folders then the file name also has the information about the number of frames that were stacked and the frame percentage that was stacked as this information was previously stored in the folder name the prefix option allows you to prepend some text to the beginning of the output file name suppose you start with a movie file with this file name and you enter Jupiter for the prefix then you might end up with this for your output file name the Jupiter part is due to the text that you entered for the prefix you get the underscore for free the a s underscore P 20 means that 20% of the frames were stacked if you selected save in folders then this would be missing from the file name and the file would be stored in a folder named a s underscore P 20 the G 6 means you selected the gradient quality estimator with 6 for the noise robust value the a P 12 means you use 12 line points if you selected drizzle then you also get underscore drizzle 15 or underscore drizzle 30 included in the file name if you select resample 2 X you get resample 20 included in the file name if you select simple filename for all then your file name won't have all the extra bits which tells you how the stack was made this version of Auto stacker it has a more file options button which brings up a window with some options of what to do after the stack is made it says experimental so I will leave it for you to play with under Advanced Settings we have this HQ refine option the tooltip says finer alignment but also a bit slower usually worthwhile on good data I always keep it checked but I checked it wants to see what the difference might be I notice that the time for image alignment was cut in half by unchecking the box but this is such a small percentage of all that it does it really doesn't make sense to not use HQ refine even with a slow computer next we have drizzle and we can select off 1.5 X or 3 X the idea behind drizzle is that it is possible to get a higher resolution image than what was captured because we had many frames of the same object and the object is moving around a little from frame to frame in practice this doesn't work for planetary imaging if you select 3 X your image will be three times bigger in both width and height but it won't be that much different than using no drizzle at all and resizing the final sharpened image to be three times larger what this means is that if you use 3x then you'll probably want to shrink the final sharpened image back to the original size when you're done auto snacker only has the 3x algorithm when you select 1.5 X Auto stacker will use the 3x drizzle and resize it in half to give you the 1.5 X drizzle I use drizzle when my image is small like Mars or if I'm using a smaller telescope this way I have something larger on my screen when I'm applying weight of it sharpening and I can see what I'm doing when finished I often resize it back down because it looks artificially enlarged the tooltip for resample 2x says resample frames during stacking only for monochrome recordings it seems to work for color though the stacked button is disabled until you add align points you control the align points with this left side of the preview window most of it is self-explanatory you can add a line points by clicking on the image you control the size of the rectangles with the controls in this region you can create a custom sized rectangle by selecting manual draw and clicking twice on the image you complete a single align point by right-clicking near the red dot of the one you want to eliminate or delete all of them with the Clear button Auto stackert will automatically place align points using these controls here you can see what the men bright value does by playing with it setting it to a hundred on this image causes few align points to be placed in only the brightest part of the image setting it to ten causes many more to be placed one mistake many people make is to use a line points that are too small imagine you were given this tiny part of this one frame and asked to align it to the reference image it is like doing a jigsaw puzzle and you pick up a piece that is all blue the reference image is on the box the puzzle came in and it has a large blue sky if the jigsaw puzzle has large pieces it makes it possible to place it on the reference image if you knew two artists tracker then here's what works for me check the replace checkbox so every time you press the place ap grid button it will start from scratch keep trying different sizes until you end up with between 10 and 20 align points you may need to manually add a point or two to make sure you have every bit covered if you have a sharp image with lots of detail then you can use smaller line points I've stacked with only four line points when doing Mars with bad scene help Auto stacker do its job by giving it a line points that aren't too small this is the end of this video after Auto stacker you will want to sharpen your stacked image I have two videos on using Reggie statics one video shows how to use the wavelet controls and the other video shows a few of the other image enhancing controls of Reggie stacks if you want to learn more about how histograms can be used for capturing and processing check out the histogram video click on the bottom right for a list of all my planetary imaging videos you

Channel: wwgeb

Views: 85,192

Keywords: AS!2, AutoStakkert!2, AutoStakkert, AS2, RegiStax, Astrophotography stacking, Astrophotography software, Planet stacking, image stacking, lucky imaging

Id: Ci_aMmO4DBA

Length: 27min 46sec (1666 seconds)

Published: Sun Aug 30 2015