Enhancing glossiness, iridescence and sheen

A good bird photo image is an unobstructed view; in focus; showing the “gleam” in the bird’s eye; good detail across all feathers; and the bird should be doing something interesting like feeding a chick or catching an insect.

However there is also the question of capturing/emphasising “gloss” or “iridescence” on the bird’s feathers. It may be a question of personal preference but I haven’t seen any discussion of this type of effect, which in some ways is the opposite of pastel shading. If the sheen is there, what kind of settings in DT will show it to best advantage?

Is it about the maximum intensity on the highlights, or high contrast? Is there a combination of DT settings that mimics printing on high gloss photographic paper? Or is it just the optimum lighting on the bird when the photo is taken?

I know its a very general question, but maybe there are some dos and donts.

That’s an aweful lot of rules there. Sounds like something best suited for computer-generated imagery, since you already have laid down the algorithm. Anyway, not my cup of tea.

Gloss is mostly a contrast of luminance. The first step is to increase global contrast, which also gives you a free acutance (aka fake perceptual sharpness) boost with no edges effects. Any kind of S curve on luminance, or a sinusoidal curve in tone equalizer will get you there. Global contrast is to be set for the global rendition, so increase it as much as possible while keeping a fair balance in the image.

Then, you can double that with another pass of contrast through S curve/sinosoid, but masked only on the regions you want to enhance.

And then, of course, you get local contrast, meaning : how much will an object stand out from its neighbourhood (which again fakes optical sharpness good enough to fool human eyes). To enhance this, you get contrast equalizer, local contrast module and after next Christmas the “diffuse and sharpen” module (although diffuse and sharpen deals with real sharpness, aka steepens the MTF). Beware, though, that they all induce edge artifacts like edge replication, gradient inversion and halos when used too far, even though they all come with various strategies to mitigate this problem.

Finally, I don’t know for feathers and the like because they have prismatic structures with very peculiar optical properties (when you know that peacock feathers are actually pitch black yet full of iridescent colors, you start doubting everything), but if you look at varnished colored surfaces, highlights and gloss are usually desaturated compared to dimmed areas. This is a by-products of adding white light to a base colored surface (Abney effect): it gets less saturated and takes a slight hue shift.

To simulate this in a physically-accurate fashion, you could use a color calibration module set in B&W (for example, use the B&W from luminance preset), blend this module in addition with some transparency and mask it on the glossy parts.

To get the deep, colorful, dimmed colors of the glossy surfaces, you can finish by increasing the saturation of shadows and perhaps midtones in color balance RGB. With extra saturation in shadows and extra white ligh in highlights, you should get a believable enhanced gloss.


Thanks Aurelien - exactly the info I was looking for! I’ll try out those techniques on some old images to see how far I can push it.

Re the rules for bird photos, you have to remember that birds seldom stay put for very long so you can’t control much about the shot you take. That set of rules I listed is my idea of heaven, but only a starting point for pro photographers. They have the right equipment and settings, but also incredible patience waiting for exactly perfect conditions to get their money shot.

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I tried doing that and the results are interesting, but couldn’t you do something very similar under Color Balance RGB by adjusting highlights in the perceptual brilliance and saturation sliders within in the master tab, and control the extent with the fall-off masks?

No, because that brilliance tool uses a perceptual color appearance model that precisely aims at discarding the Abney effect (aka it’s designed to keep hue unchanged, so its only the same color at a difference brightness/lightness). To get this effect, you need to work in a physical space and add a constant on top of RGB values, it’s the closest you can get from the real thing.

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Ok, thanks. I’m coming the believe that I’ll never get on top of all these little nuances… :wink: