PixInsight Screen Transfer Function: Basic Confusion Cleared Up!

The STF process of PixInsight gives you the full freedom to display your images in anyway that is useful while processing data. However, first time users of Pixinsight often get confused while applying processes to their data and not updating the STF accordingly. At some point when they do, they are very SURPRISED at the calculated STF result! This video explains what is going on.
#PixInsight #STF #Adamblock #masterclass

[@Spaced_Out_Bill]

I almost lost my mind using STF when was a new user! Thanks for all your great videos. I feel I kind of understand STF and Histogram process a little better now.

[@AdamBlock]

Thanks!

[@dances_with_drones]

Hi Adam, The biggest gem I got from this video is the history explorer. As I learn more from your fundamentals, I can go back, see mistakes I've made, and make corrections on previously processed images.

[@AdamBlock]

Great!

[@MatthewHolevinski]

Wonderful video as always Adam. On a side note it was a pleasure to see a new antennae galaxies photo, I haven't seen one in quite some time.

[@AdamBlock]

Thanks for checking it out.

[@yourfavoriteastronerd]

Ohh I know that word (wtf) in Spanish very well as this happens to me a lot. I think you are a mind reader. Thank you!

[@scottbadger4107]

Great video Adam, thanks! A question I was left with is *should* the MSLT settings be adjusted so that the recalculated stf shows a smooth image, or could the settings be optimal and the image sill looks like a mess but safely ignored? I've seen a similar effect with NoiseXterminator that has a lot less latitude of adjustment. To get around it, I've been doing a minimal stretch before any NX application, and then finishing the stretch after applying NX. Is that valid? On a similar(?) note, in the usage notes for StarXterminator it says to remove stars in the linear phase and to create a stars only image, use simple subtraction between the original and starless and then to NOT apply an stf auto stretch on the stars only image as it will, "[...] destroy this STF information and give a false impression of the significance of very faint background residual pixel values."

[@astro-optics]

OMG ! Thanks !Thanks!Thanks!

[@waynearnoldCanada]

Regarding viewing history of an xsif file: When I open a master from WBPP 2.5 I can see history values in the FITs header but when I open history explorer there is nothing there. Cannot figure out why as I see when you did this in this video, you were able to see each process and the details of how the process was run. I would love to be able to do this.

[@davidleejenkins]

Well explained Adam!

[@AdamBlock]

Thank you.

[@andrewj1132]

With great respect, Adam, I think I’m confused here by exactly what you’re saying in this video. I thought the rule of thumb when applying a change to a linear image was to reset and then reapply the STF to see what affect the new changes had made to the appearance of the image. Is that what you’re saying? Or are you saying something else?

[@AdamBlock]

You need to recalculate the STF (you don't need to reset it) ..but yes, this is what I am saying. I am also saying there isn't anything special or worrisome about a calculated STF- which is what the person did not understand- the representation you see on the screen is there to help you. It does not change the data...so all views of your data when manipuating the STF are CORRECT. It is just that renderings are more useful and others if you want to understand how you are affecting things with each process.

[@andrewj1132]

Thanks. :) That makes it clear for me. Thanks also for pointing out that I don’t need to reset. Out of habit I reset before reapplying STF. I think I wasn’t sure whether new STF hadn’t “inherited” something from the old one. I now know it doesn’t.

[@AdamBlock]

@@andrewj1132 Correct.

[@billblanshan3021]

Lol @ WTF. Another great informative video Adam!

[@AdamBlock]

I am terrible at making thumbnails... had to try something. :)

[@billblanshan3021]

@@AdamBlock lol

[@EelkoG78]

Hi Adam, just wondering: Why don't you unlink the STF, top left icon, and use it that way? To me it brings out a more balanced image.

[@AdamBlock]

This image is already color corrected. There wouldn't be a big difference in this case. If this was an image of a nebula (red) it WOULD mess up the color balance. So do not unlink the STF (do not recalculate per channel) on color corrected images.

[@aerozg]

So do we apply STF after each manipulation of the image, each time we a script or process? Is that the correct thing to do, to see where we are going with the adjustments? Because what i see in youtube tutorials people don't really do it, but still end up with correctly processed end results.

[@AdamBlock]

I wrote a long answer... but then decided to give up. The answer is the same as given below with @andrewj1132 . Stretch Academy would be a great course for you if you are interested. Feel free to contact me through my website.

[@aerozg]

@@AdamBlock i am already a member of your Fast Track program since last week, but i guess learning how to stretch correctly is the most important thing to focus on. Stretch Academy looks like a great place to start. The trouble with PixInsight for absolute beginners is that everybody and their grandma seems to be making beginner tutorials these days. These people have barely scratched the surface and have only rudimentary/superficial knowledge and some lucky results that they got by following somebody else's steps, yet they feel compelled to share this with the world. Which is actually not helping, but doing totally the opposite. I will finish Warren Keller's book and learn the old ways first, before delving into modern techniques like GHS and what have you. I want to learn the WHY, not just the HOW. I will supplement this with your content and a volume of repetitions. Thank you for your time and energy.

[@AdamBlock]

@@aerozg I see. It is great you are going through FastTrack. The real answer to your question is in Fundamentals. If you go through my videos step-by-step you will have a consistent "world-view" of how things work (particualrly the WHY). Stretch Academy is included..but really I would suggest start watching the Fundamentals videos. (You can apply the purchase of FastTrack Towards it.)

[@aerozg]

@@AdamBlock sounds about right. Thank you again!

[@georgeshoup4046]

I would benefit from knowing when NOT to use STF. After some processes it is best not to use it in my opinion.

[@AdamBlock]

There is no rule. It is just a way to look at the data. The key is to understand what is being shown- in this particular case the person I describe thought that the STF was *doing something* to the data. It isn't.

[@AdamBlock]

No...I am not done. Think of it this way- if you take a 16-bit image and NEVER CHANGE THE STF- You will always see a black image with (maybe a few stars). You can't possibly process an image in this state- because you cannot see the changes you are making. So you adjust the STF...how much? As much as necessary to see how you are changing the image with each process applied.

[@georgeshoup4046]

Thanks