INVESTIGATING - Local Contrast Enhancement, Clarity and Midtone Contrast

[Pica]

Hello Forum Friends,
Background: I have been working with the digital darkroom for more than a decade, and I am now performing a deeper exploration in the area of contrast. I have read through information which I have found earlier (e.g. at luminous-landscape, lonestardigital, moderskeppet, as well the one here (BTW I have told Donald that I find the CiC tutorial very good). However, I now need to dig deeper, in order to enhance my post-processing flow further.

I have practically been using LCE (with High pass and Unsharp mask) and Clarity (in Camera Raw) for a while, as well as viewing the results, to receive some clues. However I find it hard (which I also learned others do) to wrap my head (which is said to be cleaver by others ) around LCE on a more in fundamental level. Which also includes to describe to others how it operates and differs from e.g. the Clarity-slider.

Hence, I am wondering if knowledgeable parties here could help me and other interested readers, to describe the similarities and differences between:

- LCE (Local Contrast Enhancement)
- Clarity (in Adobe Camera Raw)
- Midtone contrast

What are the similarities, differences and for what applications are they typically good for?


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As always, thank you for your co-operation!

[DanK]

When in doubt, check the tutorials on this site first. They are excellent, and it's more efficient to start with them and then post more specific questions.

All three increase the appearance of contrast, but they are very different. Local contrast enhancement and clarity adjustments are a form of sharpening, whereas standard contrast adjustments change the allocation of tonality across the entire image.

Local contrast enhancement is a difficult concept to grasp (at least, I think it is), but there is a good explanation in the 'editing and postprocessing tools' section of the tutorials page. For a somewhat less technical introduction, check out the explanation on the Luminous Landscape site.

Many people (I among them) consider the lightroom clarity adjustment to be a form of local contrast enhancement, although I think the underlying math differs from the unsharp mask method used as an illustration in the two sites I noted above. I use them interchangeably, depending on which software I am working in at the moment.

By "midtone contrast" I am guessing you mean enhancing the overall contrast of an image by expanding the tonal range of the midtones. This is completely unlike local contrast enhancement, which is underneath it all a form of sharpening. People are more sensitive to tonal range in the midtones than in the extremes. Therefore, a standard way to increase the overall perception of contrast in an image is to apply an S-curve, which compresses the portion of the total tonal range allocated to the tails of the distribution and reallocates that tonal range to the midtones, thereby spreading out the midtones so that they occupy a broader tonal range. This is explained in the "Using the "Curves" Tool in Photoshop" tutorial in the same section of this site's tutorial pages.

Once you have looked at those, re-post with questions they didn't answer for you or with questions about things that weren't clear, and folks here can try to fill in the gaps.

[rpcrowe]

I use NIK Viveza Structure both globally in the overall image and, most often, selectively utilizing the control point system.

I don't really technically know the difference between any of the above three:

- LCE (Local Contrast Enhancement)
- Clarity (in Adobe Camera Raw)
- Midtone contrast

All that I know is that I use the NIK Viveza Structure Slider on just about every image I process and have been doing so for years - IMO, quite successfully!...

[proseak]

Here's a place to start -

https://www.cambridgeincolour.com/tu...nhancement.htm