Stretching with Development....how much?

[nickatnight]

Hello,

I've been experimenting with different levels of stretching in Development, and how they affect later modules. Is there any advise on the best level to achieve? Should I overstretch early to get in there and deal with issues in the data, or should the stretch be more to a level you'd like the final image to be? It seems to me if I overstretch, and then wipe for say color bias (very red modded DSLR data stacked in DSS), I wind up desaturating the image. Any advise here would be appreciated.

Thanks - Nick

EDIT: I'm adding a link to a stack of the Horsehead/Flame I shot recently if you'd care to advise specific to my data. Thanks!

https://www.dropbox.com/s/9cn9aggjehulk ... x.TIF?dl=0

[admin]

Hi Nick,

Apologies for the late response. Busy times...

There is no completely 'right' answer to your question and the best advice I can give you is to bring out what you think is important. If it's a galaxy, bring out that (but not the background). You, yourself, will know with what purpose you imaged an object - did you image the Pleiades as a cluster, for its nebulosity, or because you're interested in the dust that inter stellar medium around it?

You may have come across the distinction in StarTools between global stretching and local stretching.

Using the Develop or AutoDev module (the latter in combination with an Region Of Interest is recommended - see below) lets you perform your global stretching. 'Global' meaning everything in the image, regardless of its brightness and/or location is affected.

Screenshot-Untitled Window.jpg (307.01 KiB) Viewed 3678 times

Once you're happy with the visibility of the general object itself, so that it stands out against the background, (this is your global stretch) you can start bringing out detail within the object(s) of interest by performing local stretching. Local stretching is performed by the Contrast module (medium-to-large local contrast optimisation), the HDR module (medium-to-small local contrast optimisation) and the Wavelet Sharpen modules (small-medium detail enhancement). A special mention is reserved for the Life module, which allows you to perform medium-to-large area enhancement (sort of functioning like wavelet sharpening at medium-to-large scales).

Noise is always a consideration when stretching, though StarTools is very capable of keeping track of its development and removing it once Tracking is switched off.

Hope this helps!

[nickatnight]

Thanks for the response Ivo. Very helpful info for understanding what the tools are doing.