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RETOUCH PRO FREQUENCY SEPARATION PLUS

With Linear Dodge (Add), the formula for the blend is (A + B). Is it really? (Spoiler alert: nope) Let’s test it. Various online sources state that Linear Light is a mix of Linear Dodge (Add) and Linear Burn. When the result is out of scale it’s clipped to 0 or 255, unless further blends are to be calculated. If you normalize them first it’s just the same Let’s pretend that we have the following values 1.Ī brightened result, that must be normalized with a 255 factor to be meaningful and appear darkened: As an example, Multiply is a well known darkening blending mode, but not if the multiplication is calculated with pixel values in the (0,255) range. Some blends are easier to understand if applied on normalized values, i.e.

Blending Modes mathsīlending modes are arbitrary ways to mix two layers – say a Base (B) below and an Active (A) above – according to a formula. They are 100% identical, but why? And also, why different Apply Image settings for 8/16bit? That’s not been discussed very much (if at all): to properly understand we need to get into blending modes maths. That is to say: the original layer, and the same built with a Low + High frequency decomposition.

You should end up with this simple setup:

Optionally, clip H to the L layer (Alt or Option click the line in between the L and H layers in the Layers palette).

Change the H blending mode to Linear Light (LL from now on).

Select H, then Image > Apply Image with the following settings.

Apply GB to L, with a radius large enough so that the detail that you want to migrate to the other layer disappears.

Duplicate the original (O) twice, and call the two new layers L (low) and H (high).

There are two ways to deal with a proper frequency decomposition, depending on whether the file is 16bit or 8bit. In the early days we used to combine the GB and HP layers (the latter in Linear Light blending mode, 50% opacity) but that’s not really precise enough for our purposes here. I’ve picked this image for most of the examples – it’s a 1887 painting by Abbott Handerson Thayer, a portrait of his daughter from the Smithsonian Institute collection. Whereas if you High-Pass (Filter > Others > High Pass, HP from now on) with the same radius you’re doing the opposite: you’re left with everything that belongs to the smaller-than-10px range (only the high frequencies are allowed to pass – hence the filter name). detail) that belong to the smaller-than-10px range. radius 10px, you’re getting rid of all the high frequencies (i.e. When you filter with Gaussian Blur (Filter > Blur > Gaussian Blur, GB from now on) e.g. In the more familiar realm of images, you can think of high frequencies as describing thin detail (given a defined area, a lot of stuff happens there), while low frequencies are in charge of spatially slower changes:Īs opposed to the signal wave example, with images we usually deal with frequency ranges. If you want to understand the concept better, this article goes in much more detail and will blow your mind too.

Low frequencies are at the bottom, high on top, black is the result. a sound wave no matter how complex can be built composing “pure” frequencies. I assume that you already know what we’re talking about, TL DR any signal, e.g. Spoiler alert: I’m interested in Frequency Separation as a tool for a broader set of manipulations not limited to, nor particularly focused on, beauty/skin retouch.

RETOUCH PRO FREQUENCY SEPARATION PLUS

I’ve thought to revisit the original article to give the subject a new coat of 2021 paint, plus all sorts of new detours. That was early 2009, way before Frequency Separation was cool, then popularized/mainstream, then possibly cool again.

Finally, you can use lipstick to make the lips look well defined.Īdjusting contrast and brightness allows us to emphasize or soften details: as a result, the image becomes more punchy, deep and interesting to our eyes.A long (long) time ago I wrote an essay on Frequency Separation, even if the main subject was disguised in the more approachable title “Notes on Sharpening”. For the face you can apply blush to give a healthy look, earth to intensify the natural shadows of the facial contour, the forehead and chin and brighten the areas you want to highlight by making them more prominent - such as cheekbones, lips and the central part of the face. Highlight the strategic points of the portrait by enhancing the eyes with eye shadow, eyeliner and mascara. Lipgloss - Blush - White teeth - Hair coloring Make-up is made up of a set of features that aim to enhance any face,but sometimes it alone is not enough to "beautify", so we try to search for “nuisances” that could potentially "disturb" the face and then minimize them by correcting them.