Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Processing Issue -- What Am I Doing Wrong?

  • Please log in to reply
6 replies to this topic

#1 NMCN

NMCN

    Mariner 2

  • *****
  • topic starter
  • Posts: 259
  • Joined: 20 Sep 2006

Posted 20 April 2019 - 01:29 AM

So I'm running through the processing steps for a LRGB image and I've just finished an application of MLT and I'm thinking its looking pretty good (left side of screenshot).  Then I apply an STF and HT to make it non-linear and I get the garbage image on the right side of the screenshot.

 

What happened?  Is it supposed to look like this?  Did I do something wrong?  I have six hours of integration data collected and I have spent a week and half trying to get a decent image out of it.  I know it shouldn't be this hard, so it has to be operator error on my part.  But for the life of me, I can't figure out what I'm doing wrong.

 

 

Workspace04.jpg



#2 H-Alfa

H-Alfa

    Mariner 2

  • -----
  • Posts: 234
  • Joined: 21 Sep 2006
  • Loc: Spain

Posted 20 April 2019 - 08:07 AM

Seems that your non linear image has an STF applied. Maybe is this?

Enviado desde mi MI 5X mediante Tapatalk
  • NMCN likes this

#3 Monkeybird747

Monkeybird747

    Ranger 4

  • *****
  • Posts: 399
  • Joined: 31 Aug 2017
  • Loc: Louisville, KY

Posted 20 April 2019 - 10:59 AM

Yes, as H-Alfa mentioned it does look sort of like a “double stretch”. If you are using the method of transferring the STF to the HT tool, make sure that after you drop the new instance icon on the HT window you reset (remove) the auto stretch from the image. Then apply the HT stretch.

Using the STF as your stretch is not always the best option. Try stretching manually so you can monitor clipping. There are a few different ways to stretch an image. I only use the STF transfer method for masks.
  • NMCN and elmiko like this

#4 NMCN

NMCN

    Mariner 2

  • *****
  • topic starter
  • Posts: 259
  • Joined: 20 Sep 2006

Posted 20 April 2019 - 11:48 AM

bangbang.gif

 

It was operator error indeed.  I don't know why, but I had it in my head that I should come up with the same result even if I removed the stretch after applying the HT stretch.  Obviously not!!!

 

Thank you H-Alfa and Monkeybird747 for finally getting it through the dense matter that is my brain that I need to remove the auto stretch first.



#5 jhayes_tucson

jhayes_tucson

    Fly Me to the Moon

  • *****
  • Posts: 6782
  • Joined: 26 Aug 2012
  • Loc: Bend, OR

Posted 20 April 2019 - 11:58 AM

The green underline on the name tab indicates when the display is being stretched.  PI is very smart about separating the way that the data is displayed from what is actually in the data itself.  So that means that you have to understand what you are looking at.  The UI is full of various subtle displays (mostly using color) to indicated the state of things so it's a good idea to take a course, read a book, or go through the reference materials to understand this stuff.  PI is both very broad but also very deep in its capabilities so it can take a long time to learn it all.

 

John



#6 bobzeq25

bobzeq25

    Hubble

  • *****
  • Posts: 15474
  • Joined: 27 Oct 2014

Posted 20 April 2019 - 03:52 PM

bangbang.gif

 

It was operator error indeed.  I don't know why, but I had it in my head that I should come up with the same result even if I removed the stretch after applying the HT stretch.  Obviously not!!!

 

Thank you H-Alfa and Monkeybird747 for finally getting it through the dense matter that is my brain that I need to remove the auto stretch first.

You need to remove the STF to see what you're doing.  It doesn't mess anything up.

 

As mentioned, SRF + HT is a pretty strong stretch, and you're on autopilot.  Try ArcSinh stretch (remove the STF first so you can see what you're doing).  It's a fairly simple process, and you have total control.  Stretch until the background is preety bright, click Estimate Black, and move the slider just enough to remove the artifacts.  2-3 interations can be good, 1 works.


Edited by bobzeq25, 20 April 2019 - 03:52 PM.

  • NMCN and kyle528 like this

#7 NMCN

NMCN

    Mariner 2

  • *****
  • topic starter
  • Posts: 259
  • Joined: 20 Sep 2006

Posted 20 April 2019 - 06:40 PM

Thanks all for the tips on not using STF and HT.  I'll be honest and say I was in a rush to get an idea of what the image might look like.  My take away after all of this is to have patience, trusting that the image will reveal itself in the end.


  • bobzeq25 likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics