DDP?

[Nils_lars]

I did a search before asking and I see mention of DDP being part of this program but I cant find it , I have always used this as a starting point in my processing.

Is it not the best way to do an initial stretch?

I have processed a few photos so far using PI and I have been following Harrys online tutorials and using that order for processing.

The only real problem I have had is HDRWT leaving dark circles around my stars even with deringing selected and that ACDNR being to strong and leaving my background blotchy but thats user error im sure from me being a noob with this , its a very powerful program and kinda over my head.

[Nocturnal]

Hi,

I suppose you need to know what DDP stands for and then it's easy to find

All Processes->DigitalDevelopment

I don't think it gets used a whole lot but don't let that stop you. I suspect most people use the histogram tool for non-linear stretches. As I recall the curve type is more advanced.

As far as HDRWT goes you may need to adjust the deringing sliders to find the right balance between effect and protection.

It's hard to help you with ACDNR without any details. If you're not using it I suggest trying the luminance mask option.

Please keep your questions focused to a single topic per thread so it's easier to discuss them

[Harry page]

Hi Nails

I hope you have found DDP and as sander says try if you like but better results can be achieved by using the histogram to stretch your image and other process like Hdr wavelets  8)

Again as sander says play with the "amount sliders" to increase protection for your image, some times on a difficult image I also use a lum mask at the same time  

Lasley on ACDNR I tend to use std dev of around 2 on the lum and 3 on the chrome , but with a lum mask enabled   you can use a larger std dev say 4 and 5 for the background , but you have to be very careful as that blotchy background can appear . I personally do not do the large scale noise reduction as I think sometimes less is more and prefer to see a little noise.

Keep at it and and ask away sometimes its the only way to learn


Harry

[Nocturnal]

Hi,

like Harry I also dislike the splotchy background that can result from large scale ACDNR. This is my typical sequence:

- DBE
- background calibration
- color calibration (last two aren't needed a whole lot after DBE but I do them anyway)
- histogram
- small scale ACDNR
- histogram
- refinements like HDRWT, lum masked saturation curve etc.

[mmirot]

I recommend you use a star mask with HDRWT.  You will forget all about DDP once you can do this.

Max

[Nils_lars]

Oh it is in there ok , I assumed that the histogram tool was just as good its just that old habits die hard.

Sorry about multiple things in one post , I went a little crazy

I have been using the lum mask and I do use these tools pretty much like you guys are suggesting already , I think I just need to get a little better using it.

I havent tried the star mask trick yet with HDRWT , thanks for all the suggestions guys.

[Nocturnal]

Good luck Nils, I'm sure you'll get the hang of it quickly. Come back with more questions when you get them.

[mmirot]

Yes, The histogram tool is quite different from other software.
No more interations of curves and levels like PS.
 No real need for DDP either.

HDRWRT is easy to use,  except without masking the stars may look over sharpened

Max

[Juan Conejero]

Hi Nils,

Welcome to PixInsight Forum.

I haven't too much to add to what already has been said. DDP is, IMHO, an obsolete technique since many years. I implemented it in PixInsight mainly for completeness, but it is #1 candidate to be included in the new Obsolete module that will ship with PixInsight 1.6. The Obsolete module will be included in PixInsight's distribution, but it won't be installed by default (the user will have to install it manually if desired).

We have many and much better tools to do what DDP intends to do. Anything that you can try to do with DDP can be done with HistogramTransformation and CurvesTransformation, but with surgical accuracy instead of a rough two-parameter stretch where you have to "guess" the actual function being applied. Our ATrousWaveletTransform  (ATWT) tool includes a large-scale hyperbolic transformation that does just what DDP does, but restricted to dimensional scales where all drawbacks of DDP are easily avoided. Finally, for dynamic range management we have HDRWaveletTransform (HDRWT). To compare DDP to ATWT and HDRWT, think of a hammer and a scalpel.

[C. Sonnenstein]

So... the next candidate to Obsolete module can be UnsharpMask? 

[mmirot]

Not so fast Juan,

I would not call these obsolete yet. Just older.

Max

[C. Sonnenstein]

In my opinion, the old things in astrophotography are obsolote. Do you thing film astrophotography is only old? Nobody today shot the sky with photography emulsions, because are totally obsolete. All cameras are CCD detectors or DSLR cameras.

Other example is Unsharp Mask. This technique was born in the 70's with analogic format. Today, for example we can do these type of tasks much better with wavelets. ATWT in PixInsight can isolate structures in a given dimensional scales, and then perform something similar to USM, but more controlable.

My two cents.

[Nils_lars]

I appreciate all the help already , im sure I will have more questions once I really can figure out what im doing.

So Juan what you are saying is to do a proper or better job at replacing what I normally get from a DDP I need to do a Histogram transformation and a ATWT and a HDRWT or just 2 of those 3.

What order should they be done in or is that subjective?

I am really used to attacking my data and then when it gets out of hand I beat it back with a stick and then attack it some more , hopefully I can learn some finesse over here

[Harry page]

Hi

We can get rid of unsharp mask , when,    I said when someone shows me how to use ATWT    



Harry

[mmirot]

New users should be able to start with fimilar tools.
I think there is space for a older un favored process modules in the menu.

Max