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dmstraker

Curve Blends for 'luminosity masking'

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UPDATE: New post including macros here: https://forum.affinity.serif.com/index.php?/topic/38379-luminosity-mask-selection-macros/

 

I've been experimenting with doing 'luminosity masking' with curves and blend ranges. Here's the result.

 

Attached is a 'photo' file with three groups - just copy and paste one of these into any photo, either at the top level or as a child. Then open the group and double-click the curve to adjust just the named luminosity range (eg. 'mid tones'). As it's a curve you can also do it selectively by colour.

 

It works by constraining the blend range on each curve. Click on the cogwheel to see this.

 

There are three groups because I wasn't sure which way to chop up the spectrum, so I've done three ways: curved, rectangular and triangular. Please do try them and let us know here which works for you.

 

I tried doing these as macros, but the macro system stopped me doing things like naming adjustment layers and grouping. I guess it's not mature enough yet for such actions. So I resorted to the cut-and-paste method. This forum also doesn't like you uploading .afmacros files (ahem). But if you prefer macros, I've put them on one of my websites here: http://changingminds.org/etc/affinity/Curve%20Blends%20V1.afmacros

 

 

This is still in the experimental stage - please let me know what you think.

 

Edit: Upated version in post below.

Curve Blends V1.afphoto


Dave Straker

Cameras: Sony A7R2, RX100V

Computers: Win10: Chillblast Photo with i7-3770 + 16Gb RAM + Philips 40in 4K; Surface Pro 4 i5

Favourite word: Aha. For me and for others.

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why did you design the highlights and shadows in such a weird way?

 

modifying the curves leads to a black spot at about 80% and a brighter stripe at 100 and 50%

this is not actually highlights 

 

Highlights are usually the upper third of the tonal range and their curvature/ coverage has two be designed in a way such that highlight+shadow+midtones produces a 100% coverage of all tones


 

 

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Thanks, MBd -- I'm experimenting and your feedback is just what I wanted!

 

The triangle is intended as additive in overlap and rectangular as wholly separated regions. The curves are an initial attempt at smoothing between regions.

 

I'll continue to play and improve.


Dave Straker

Cameras: Sony A7R2, RX100V

Computers: Win10: Chillblast Photo with i7-3770 + 16Gb RAM + Philips 40in 4K; Surface Pro 4 i5

Favourite word: Aha. For me and for others.

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I think there is currently no way to dial this in exactly 

 

when you do this using just straight lines like 90degree angle, this makes very bad transitions 

but when you use nice curved shaped lines, you can not match shadow/ highlight/midtones really 100%

 

that being said, it might not be needed at all to match them 100%

 

I for myself would always just do them from scratch anyway as I see fit, it is just so fast in AP and one will just always tweak them layer anyway (that is what works for me)

 

btw you can group layers already, but it is a hack

/ you create a layer

/ press cmd g 

/ set up your assistant options in a way so that new adjustments are added on top, rather than nested, then you can build up an adjustment layer set inside a group and you can also rename the, it is just bit buggy but like macros should definitely support multiple selections so this will be improved, I'm sure  :)


 

 

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Thinking on about this. One way of dividing things is simply rectangular, so shadows stop at point X, where mid-tones take off. Could we alternatively go with the notion of some kind of graduated curve so shadows fade off into mid-tones in a gentle overlap, etc?

 

We'd need some kind of curve for each. Assuming also that something approximately Gaussian is desirable, we could just draw a mathematical curve. But to sum to 100%, the half-curve, which is S-shaped, would need to be rotationally symmetrical. Something could be approximated to meet these requirements.

 

Let's also go into the question of whites and blacks, so we can butt right up to either end of the spectrum and give some leeway in controlling the tones around these extremes. We could do this with a half-curve each.

 

A pattern is attached.

 

Thoughts?

post-50332-0-05163100-1491065197_thumb.jpg


Dave Straker

Cameras: Sony A7R2, RX100V

Computers: Win10: Chillblast Photo with i7-3770 + 16Gb RAM + Philips 40in 4K; Surface Pro 4 i5

Favourite word: Aha. For me and for others.

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