Bringing out very faint detail

[Scottk]

What are the best tools and techniques for enhancing the brightness of details that are just barley visible above the background? For example the very faint arms of galaxies around the brighter cores.

[admin]

Hi,

Results and recommended settings/techniques will vary based on the characteristics of your dataset. However, generally, following the standard/recommended workflow (AutoDev->Contrast->HDR->Sharp->Decon) should yield optimal results.

This workflow was established precisely to progressively refine the visibility of faint detail (whether located in the shadows, midtones or highlights);

• Establish a baseline optimal global dynamic range for the entire image with AutoDev. See AutoDev docs for more info, but the point here is to establish a stretch that is as neutral as possible ("the block of marble").
• Establish optimal local dynamic range at large scales with Contrast ("the coarse features of the sculpture")
• Establish optimal local dynamic range at small-to-medium scales with ("the finer features of the sculpture")
• Use Wavelet Sharpening to detect and enhance faint signal at different scales. This is a good opportunity to bring out faint structures. It can be particularly useful for bringing out spiral arms, etc.
• Capping off with Decon will give definition to any larger scale areas defined and brought out.

In general, you may wish/need to tweak settings, based on the scale of the image and where in the dynamic range the detail is located that you wish to enhance.

It so happens a brand new HDR module is in the works for 1.8. I'm hoping to release a first cut in the next week or so.

If you'd like specific help for a specific dataset, please feel free to upload a dataset.

Hope this helps!

[Stefan B]

If the faint detail has a particular color you can also use the 'Filter' module using the 'Conservative nudge' or 'Screen' mode and playing with the filter width.

In this image of the Crescent Nebula the outer OIII shell was barely visible and applying Filter helped a lot in this case:

Regards
Stefan

[Scottk]

OK, I see that it's just going to take practice, trying out different settings, and learning all the modules options.