I’ve not spent a lot of money on post processing software. In general, I use Gimp and StarTools. After all, this hobby consumes a lot of money, if you let it. In the beginning, I chose to suffer through at the same time failing miserably with Gimp. StarTools is a powerful tool even though I’m still learning how to take advantage of that power. Let’s take a look.
The layout is very clean in addition to simple. On the left are buttons which will perform specific functions. In addition at the top are additional buttons with the following functions:
- open file
- compose a photo
- save a photo
- undo an action
- about button
Throughout the life cycle of post processing or whenever an action is completed, the buttons will highlight. Since there are a lot of options, let’s discuss workflows.
StarTools Generic Workflow
Right out the gate you can follow the workflow shown here on the left and achieve good results without knowing how each step works. Ultimately the more you know, the better the performance.
There is a lot ground to cover and it’s important to note that you can easily go to https://www.startools.org/ for additional information. Especially in the case that I leave anything out.
My StarTools Specific Workflow
After all in post processing, computer processing power matters. I use an HP laptop. It has 4 processors and 8 Gig of RAM. In essence, performance is slow. The TIF files after stacking are large and this brings me to my first action which is BIN.
Given that as designed, BIN allows you to control resolution, detail and noise based on your acquisition parameters. I, on the other hand, use it to improve processing performance. BIN also give you the freedom to simulate a 2 x 2 binning at this point verses setting APT (Astrophotography Tool) to 2 x 2 during acquisition. Consequently there is a trade off. You know your setup, seeing conditions, etc. and should prepare to minimize the trade offs as early as possible. Therefore, your workflow could include using BIN to improve detail or reducing noise. Review the difference in the images below.
The next step I perform is AutoDev with intention to identify stacking artifacts. Stacking artifacts are areas where the stacking software could not align all the stacked photos. In general, these are a result of changes in framing or orientation during acquisition. AutoDev also reveals additional artifacts because of this initial stretch. Here is an example with stacking artifacts.
Now that I know where my stacking issues are located, it’s time to crop them out. Surely this step allows for elimination of other defects that are outside of your region of interest. Take the opportunity to look for coma as well as vignette and crop them out. Inspect the picture carefully and choose wisely.
Obviously, the Crop tool has sliders on the bottom for fine adjustments in both the x axis and y axis. Although this a simple function, correct usage can save a lot of headaches later.
StarTools Wipe Function
Gradients can be seen in different forms on your photo. Light pollution is the more obvious cause of gradients. The Wipe Function can remove light pollution, vignetting and other gradients (to include amp glow). Below are the available options and clicking on them to see the results is a good start to success. But of course there is more.
What happens when you have a dark anomaly, ie dust mote? The answer is to mask it. The way masking works is to highlight in green those areas of the image you wish to be affected. Similarly, I will show in the next examples what this looks like when selecting stars. Only the stars are masked on the left side in green whereas the right side has the background masked in green. First I selected Auto, then Do. This selects most of the stars in the image based on the threshold set. You can adjust to select smaller or larger stars. For the sake of comparison and to demonstrate masking, I selected invert.
Consequently with the right side example I will remove the gradient from the background. I have one more step to take using the lasoo tool in mask. I absolutely do not want to affect the Andromeda Galaxy, so I need to mask it, meaning remove the green highlight. First I selected invert to unmask the background, then I changed the tool on the bottom to lasso. Next on the image click and hold the mouse as you go around the region of interest. Accordingly, if you make a mistake, select undo and try again. Finally select invert and the mask is complete.
With the mask generated, it’s time to perform the wipe. The initial auto dev shows you the pattern of the gradient. This knowledge should allow you to pick the appropriate choice from the top menu. If you are seeing light pollution in the form of a flat gradually changing gradient from one side to the other, then select Gradient. On the other hand if you see a circular gradient, then select Vignetting. I have the Optolong L-Enhance filter which is a dual pass narrow band filter and under those circumstances I will select Narrowband.
StarTools will automatically do a stretch for you once it completes, so in effect if you make the incorrect choice, you can do it again. In this example I started with Gradient and discovered that I should have used Vignetting.
The result here is good. I will inspect to see if additional improvements can be made. As can be seen on the bottom, there are additional options to adjust if necessary. Consequently, these options are for the more advanced user.
Aggressiveness & Corner Aggressiveness
Consider the result above and imagine the wipe left a light haze or removed too much of the wanted signal. It is important to realize the benefits of adjusting the aggressiveness and/or corner aggressiveness slider(s). Changing aggressiveness with either reduce or increase the amount removed for all options. With Vignetting, corner aggressiveness will adjust the amount removed in the corners of the image. Finally what about Amp Glow?
Take a look at that large bright star like section on the right of this image. That is amp glow from the image sensor of my dedicated astronomy camera. StarTools can remove this by simply drawing a mask over the amp glow, then choosing the amp glow algorithm and do. My experience with it says that it’s too aggressive, but it works beyond a shadow of a doubt.
All right, let’s take these important initial steps home so we can finalize the photo. Upon clicking AutoDev, you’ll see a dialogue box asking you to make a choice. The choice to make is “Redo Global Stretch,” although choosing “Stretch As Is” will not appropriately take into account the changes that were made.
Immediately, StarTools will stretch the image. It is at this time that I select a region of interest. To do this, find a location on the image, then click and drag your mouse to highlight the area. For the most part, this step adjusts how much stretch is applied to the image. You’ll have to play around to find the best location and the choice is simply by what you like. StarTools bases the stretch on levels of dynamic range in the image.
You can adjust the influence of dynamic range by sliding the “Outside ROI” slider up or down. As you do this you will see the image change. Again, it’s up to you how much to adjust and you’ll know when you see it. I tend to use this to darken the background without losing object detail. And if the image is very noisy, you can adjust the “Ignore Fine Detail” slider until you’re satisfied with the result. Once you’re satisficed, click keep.
Great job! It’s time to work on the details of your image. Before clicking Contrast, click on Mask. We need a full mask before we proceed. Click Clear then Invert then keep.
Remembering the options in Wipe, Contrast is similar. Altogether, the actions are similar, but for me I change nothing. I click do because the changes are subtle yet effective. Again, it’s up to you to find the sweet spot that you like for your image.
Next up is sharp. I believe it improves the performance of the next step and sure that’s debatable. In either case, Sharp has a lot of options. Similar to that of Registax Wavelet Sharpening Tool. The difference is that StarTools works down to the pixel rather the entire image. Here you’ll get the same message as before, adjust until you’re happy.
The definition of deconvolution is a process of resolving something into its constituent elements or removing complication in order to clarify it or as StarTools defines it, recovers details lost through seeing limited and diffraction limited conditions. Considering most of us capture photos at or near sea level and for this reason this is a must action to take.
When you enter the deconvolution module, it gives you a dialogue box. The best answer is to generate mask automatically. It will mask everything except the stars. Alternatively, you can generate the mask manually or not generate on at all.
Once generated, StarTools will immediately begin the deconvolution process. The process will take some time to complete. Once done do a complete review of the stars looking for any anomalies generated by this process. If you see anomalies after the first iteration, reduce the radius. Otherwise increase the radius till you see the stars change then slightly back off. Once you’re happy select keep.
HDR or High Dynamic Range is the tool to use when brightness hides details by being either too bright or not bright enough. In other words, StarTools will optimize the dynamic range in local areas of the image. As with other modules you have choices at the top. I like them and recommend using the algorithm option at the bottom which give you additional choices. Specifically start by reviewing the first algorithm by clicking the before/after button. Then using the arrows next to the algorithm option, change the algorithm. Repeat the before/after checks for all algorithms.
In general I typically use Tame Highlights or Reveal DSO Core as they work best with my acquisition setup capabilities. Take the time to review each of the results and chose what works best for you. It’s also important to note that after you keep one change, you can revisit HDR and apply another algorithm.
Similarly with a few of the other modules, there are a lot options to achieving the correct color in your image. I generally want to start as close to correct in order to minimize the number of adjustments required. Therefore I start with the options at the top of the screen which are Constancy, Legacy and Hubble.
As the algorithm is working you’ll see at the bottom right the amount of adjustment made to the Red, Green, and Blue sliders. Once complete, this is where I make additional adjustments to the color. This module does a great job.
StarTools states, “Signal evolution Tracking data mining plays a very important role in StarTools and understanding it is key to achieving superior results with StarTools.” In short, they’re saying that this software will do a better job of noise reduction because it tracks every pixel in the image. Let me show you. Choose stop tracking and do noise reduction. Choose your algorithm then adjust the grain size until the noise can no longer be seen. Click next.
StarTools will take some time to perform the wavelet noise reduction processing. So grab a drink and snacks. Here’s the before and after example.
You may want to zoom in to see the noise detail between photos. Also it goes without saying that you can change any of the scale sliders to achieve the results you desire. Once that is complete, I call it done and save the image. The image requires additional post processing in Gimp, and I’m happy to do those small changes there. Having to do this in Gimp start to finish is a nightmare.
StarTools Workflow Conclusion
I have used Gimp exclusively when I started astrophotography. Moving to StarTools was a great move on my part. Certainly I cannot compare it to other post processing tools, I can say that for the investment $45 US it is worth it.
Another key point is that old adage of “garbage in, garbage out.” It’s important to make sure you acquire good data. I don’t know of a software package that fix the limitations in equipment and seeing conditions. I would imagine that Photoshop, PixInsight and Astro Pixel Processor will produce the same results as StarTools with the same poorly acquired data. With good data, StarTools competes with the higher cost packages.
To clarify, StarTools isn’t perfect. There are parts of this package that I believe needs improvement, like the Repair Module. I didn’t show that here because no matter what I do, the stars look fake. Meaning they’re perfect circles. I also have to finalize the image in Gimp. It’s very much possible my equipment reduces performance, but I’ll reserve comment for a future post.
As a beginner, the more you use this tool, the better your results will be. StarTools does a great job and I hope you have the same experience. Thanks for reading. As always, remember that the sky is the limit only when your mind is unwilling to fly. Go beyond!