Smooth skin, keep the pores

The layer separates the picture into two bands and treats them differently, which is the entire reason it does not look like a blur. A guided filter builds a base image that follows edges instead of crossing them; subtracting that base from the original leaves a detail band carrying pore structure, fine hair and grain, and nothing else. The base carries tone. The texture slider scales the detail band before the two are added back together, so at 25 per cent three-quarters of the original texture returns to the frame.

The radius of that split is derived from the width of the working region rather than fixed in pixels — region width divided by 220, about four and a half pixels on a face a thousand pixels across. That is what keeps the band being reduced pore-sized whether the portrait measures two megapixels or twenty-four, and it is why the preview on screen and the file you export agree.

Everything above happens on luminance. The chrominance of every pixel in the region is read before and written back after, unchanged, and the new luminance is clamped into the window where converting back to red, green and blue cannot clip a channel. Clipping is the mechanism by which a smoothing control quietly lightens a deep skin tone, so refusing to leave that window is not a nicety — it is the only version of this control worth shipping.

Region first. Drag it over the face, set width and height so the ellipse sits inside the hairline, then press Show what it calls skin and adjust the tolerance until the tint covers the face and stops at its edge. Everything below this point is wasted effort if the mask is wrong, and the mask being wrong is by far the most common cause of a disappointing result.

Then texture, not tone. Take the slider up until the shine and the unevenness go, and stop at the first setting where the cheek still looks like skin at 200 per cent zoom. That number is usually between 20 and 40 on a well-lit portrait and lower on a soft one. Only then reach for tone evening, and use less of it than feels right — the low band is where a face carries the colour of blood under skin, and flattening it is what produces the waxwork.

What the skin layer runs on

Base filter

self-guided, edge-preserving

Split radius

region width ÷ 220

Variance threshold

120 in squared 8-bit units

Texture slider

0 to 80%, opens at 25%

Tone slider

0 to 80%, opens at 0%

Tone applied as

45% of the slider, on the low band only

Warning threshold

above 60%

Colour

held exactly as found

• It cannot tell sensor noise from pore texture. Both sit in the same band at this scale and nothing separates them there. Smoothing a portrait taken indoors at high ISO removes the grain along with the pores, which often looks fine and is not the same operation you asked for.
• It cannot find the face for you in this release. The region is placed by hand, which on a group portrait means one face at a time and no way to copy a setting from one to another.
• It will not take all the texture. The slider stops at 80 and there is no setting behind it. A face with no pore structure at all is not a smoothed face; it is a drawing of one.

Why does this open at 25 per cent rather than off?

Because this address was reached by somebody who already knows they want skin work, and an empty rail would make them hunt for it. Twenty-five per cent is also the number this build considers correct for most portraits: it takes the blotch and the shine out of a cheek and leaves the pore band substantially where it was. If it is too much, the slider goes down to zero and the compare control is two seconds away.

What is the difference between the two sliders?

Texture removed acts on the high band — pore structure, fine hair, sensor grain — and is the control that decides whether the result still reads as skin. Tone evened acts on the low band, flattening variation in the underlying colour of the face: redness across a cheek, a patch of shine on a forehead. They are separate because they fail in opposite ways. Too much texture removal produces plastic; too much tone evening produces a mask that is one flat colour where a face used to have blood in it.

It is smoothing the background as well as the face.

The working region is covering more than the face, or the tone tolerance is too wide. Press Show what it calls skin and look: the tinted area is exactly what the layer will touch. Pull the region width and height in until the ellipse sits on the face, then narrow the tolerance until the tint stops at the jaw and the hairline. If the background happens to be close in colour to the subject's skin, geometry has to do the work the colour gate cannot.

Half the face is outside the mask and I cannot get it in.

Widen the tolerance first — it is the distance in chrominance a pixel may sit from the region's own median before it starts leaving the mask, and a face lit hard from one side spans a wider range than a flatly lit one. If that is not enough, turn the gate off entirely and let the ellipse decide alone, then keep the feather generous so the edge does not become a seam. On a profile or a face in heavy shade that is often the honest setting.

Does smoothing run before or after the heal brush?

After, always, whatever order you pressed things in. The stack runs heal, then red-eye, then skin, because a spot removed first leaves no low-frequency shadow for the guided filter to spread into a soft grey patch, and because colour work should be judged against luminance that has not moved yet. You cannot reorder it, and there is nothing to gain from reordering it.

• What frequency separation isThe split, the radius, and why a blur destroys the band that makes skin look like skin.
• How far is too farWhere the caps sit, why they are there, and what the distance readout is measuring.
• Spots and blemishesOpens with the heal brush in hand and the region already over the face.
• The retoucherEvery layer at zero, the working region waiting to be placed.