MaskedStretch vs HistogramTransform

[jkmorse]

I would like to get a better understanding of how to effectively use MaskedStretch when converting my images to the non-linear phase.  I have historically used HT, but I really like the idea that I can protect (i.e., mask) the background during my stretch using the MaskedStretch tool.  My problem is that MS only can get the image so far before running out of steam.  No matter what settings I apply and no matter how many iterations I run, the stretch under MS hits a wall and to go farther I have to switch to HT which defeats part of the beauty of MS since you no longer have the built in background mask protection. 

Am I missing something in my settings or is that wall a "feature" of MaskedStretch that is built in and can't be overcome with the tool itself.

Thanks,

Jim

[Geoff]

Hi Jim
Have you watched Harry's video on MS. It's very helpful.

[jerryyyyy]

i just looked at the video and it is great.  I guess the point is that the normal STF->HT bloats the stars....  The script does not, but also does not stretch as much... so there is a way to add the stars to the stretched DSO after doing STF-HT stretching....

I guess this is the way to go but has as many steps as my current check list for all processing....

[jkmorse]

Harry's the man so I am off to test his site.

Thanks,

Jim

[jerryyyyy]

Well, you can tell the wife is out of town since I tried to apply Harry's techniques to some very good data from the SRO dark sky's site. 

His instructions are easy to follow though detailed.  However, he is using a previous version of the Script.  That version could call a reference image/preview for a reference background.  The new version does not.

In any case, when following his instructions to set the background in the script to what you get from STF, I get very very little contrast.  This is quite evident in the 3D plot script he uses. 

Something funny here.  Stars are debloated to the point of being barely visible.  Target background is 0.25. 

[Geoff]

Well, you can tell the wife is out of town since I tried to apply Harry's techniques to some very good data from the SRO dark sky's site. 

His instructions are easy to follow though detailed.  However, he is using a previous version of the Script.  That version could call a reference image/preview for a reference background.  The new version does not.

No, he's using the latest version of the MaskedStretch PROCESS (Process>Intensity Transformations>MaskedStretch).  This is a revamp of the old MaskedStretch SCRIPT (Script>Utilities>MaskedStretch)
Geoff

[jerryyyyy]

Thanks!  Glad to see it is a procedure since I can save the Icon now.  Works as advertised.

Interesting to me that when I look at the background in the STF->HT stretched image it is much smoother than the background in the masked stretch, but I guess I am only going to use those stars any how. 

Now, I'll see if I can get the rest of the tutorial to work.... well it did!

I only did this on a L image.  I have some RGB images where the Red stars are a bit too big.  I wonder if it will work on those also, or if I have to adjust the red channel separately...