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Originally Posted by cricket1961 The one thing I need to add that I see is missing is that skin texture varies all over the face. The nose texture is different from the cheeks, which is different for the forehead etc. |
Completely agree.
Actually, the technique we outlined (above) DOES allow you to vary the amount of texture in different areas of the face. It also provides control over the depth and density of the texture by "painting" with a low opacity brush on a mask. Additionally, you can also play with the layer
Opacity if you desire the effect to be heavier or lighter.
(Warning: Lengthy discussion below)
There may be a bit of confusion over the terms we're using for skin texture. So, for the sake of clarity, let's try to better define what we're talking about.
Skin Texture 101
As you point out
Chris, one of the variations in skin texture is that it is "different" all over the face and you used the example of the "nose" versus the "cheeks". This is a great observation and we would
add to this that there is
also a "
commonality" for an individual's facial skin texture. Namely the "
density" of the pores (we'll define what we mean by density
below). However, we would pose the question, "WHAT" is specifically "different" about the skin texture in these various regions? The answer, we believe, is in the "depth" of the pores.
Whenever you look closely at facial skin texture (really closely), you'll notice that it is actually a diagonal criss-cross or a "lattice complex" (see the exaggerated examples below). To the naked-eye, the lattice can be made up of
strong creases or
nearly invisible ones. The "points" (nodes) where the lattice "crosses" each other is where there is a "pore." At their most discrete level, these pores are arranged in an approximate "diamond" configuration, with pores at each corner of the diamond.
Stepping back from the face, the microscopic lattice typically falls away while the pores (nodes) are still
slightly visible (although, these too are starting to fall away) and may now appear more visually
random. They're not
really random though. Notice how the pores still follow the lattice and are "stacked" in a diamond pattern?
SMOOTHNESS
When skin is seemingly "smooth" this doesn't mean the skin is without "pores!" It simply means the pores are "less visible." The
reasons for this, however, may not be so obvious. They're
less visible because, their "depth" has been diminished (not necessarily their size or density, which are fairly constant). This "smoothing" or "diminishing" can be achieved with makeup, cosmetic skin treatments and naturally, in photography, through digital manipulation.
SIZE
Some confusion ensues with the use of the term, "size." Presummably what is meant by the
actual "
size" of pores is how "large" the circle (dot) of each might be visible. From a distance these will only look like very small dots. The stronger (darker) the dots, the "deeper" the pores appears to be. But does this mean that the pores are larger or simply deeper?
In actuallity there are two factors here; the "size" of the dot and the "darkness" of it. These are two factors which can change what we perceive of the texture. Yet both of these contribute to what we could generally term as the "
depth" of the pores. So, the use of the term "size" is a bit
ambiguous to use in reference to skin texture and pores in general. Probably best to steer-clear of this term all together.
DENSITY
On the other hand, the "
distance" the
diamond points (pores) are from each other is fairly consistent from face to face. We call this
distance of the pores, "
density" to refer to their
collective visual pattern. In fact, arbitrarily varying this distance all around a face would probably look quite artificial. Whereas, keeping the pore "density" constant, while varying their "depth," is closer to what happens in reality.
Considering Angles
Of course, since a face has angles AND because photos are 2 dimensional, these distances WILL visually vary depending on what angle they're being viewed. In the reality, however, the individual's pore density is constant. It's just the angle which varies. So, some density compensation is necessary, depending on the face and angles that are visible. The more
acute the angle, the closer together the pores will appear. Yet,
too large of a variation of density in the wrong places can begin to look fake as well. Therefore,
delicate treatment is required here for a more realistic and natural texture.
Displacement maps are perhaps useful here, although, argueably more effort than would be necessary to emulate the effect.
DEPTH
So, what is "depth"? Depth (in this context) is the
strength of lightness/darkness seen in the pores and lattice complex of the texture. The darker the pores and lattice, the "deeper" the texture will appear. However, if you look closer at a pore, it has
highlights as well as
shadows. This is what truly gives the pores their feeling of "depth" since the presence of both "highlights & shadows" provide the foundation of 3D rendering.
Strength & Contrast
The strength of a highlight is in it's "lightness" and the strength of a shadow is in it's "darkenss." Whereas, the relative "depth" of these is in their "contrast" to each other. In other words, the lower the
contrast, the less "depth" is perceived. The higher the
contrast, the greater the "depth" is perceived.
On The Edge Of Shadows
Typically, the areas of the face that are in
greater shadow will appear to give the pores along the shadow's
feathered transition-edge a greater
contrast and thus a greater
depth. Therefore, increasing the visibility of pores around
shadowed regions (particularly at their
transistion-edges) gives a more realistic appearance to the texture. Obviously, the pores that are at the heart of the shadowed areas will be
too dark to see and the pores that are in the facial highlights will be too
light (i.e., "blown-out") to see. For this reason, it's simply easier to focus your efforts on those
shadow transition-edges where light is "washing over" the face and rolling into shadow.
Subtlety
On a subtle and nearly subliminial level, the "hint" of a lattice pattern over large open areas of skin, make it look more
even, blemish-free, and attractive. This means that any work a retoucher does with regard to skin "texture" must be
subtle; only hinting at it.
The Painting Advantage
This is where "painting the skin texture" using the method we outlined above (or a similar one) can provide greater control of these necessary "hints" of texture by the amount and depth through the use of a low opacity (soft) brush on a mask.
An added bonus of this technique is that this is a "non-destructive" method which allows you to go back and "add or remove" your texture
on-the-fly by simply pressing the "x" key to swap foreground and background colors (black & white) while painting.
As an alternative method, you could also have a series of skin textures (desaturated) in your
Patterns file and
Fill a layer with this pattern then follow our method from
step 4 onward.
Additionally, you could
Fill a layer with 50% gray and apply a
Pattern Overlay layer
Style using the "skin texture" pattern and set the style's blending mode to
Overlay (this gives you a real-time view of the texture over your image). You can also adjust the
Scale of the texture to better match the face (this is a big plus). Then follow
step 5 onward.
The Dior photo looks like it used a very similar technique.