Hi and welcome to this video about the Advanced Local Contrast Enhancer Panel version 3 for
Photoshop.
Also known as ALCE, which is the Italian word for elk.
Have you ever heard an elk call?
Next time you're out in the bush, you'll know.
ALCE is about Local Contrast, which in turn is about Contrast, and aren't we all familiar
with this concept?
Of course, we are. Contrast involves a Difference.
Example: I'm in Contrast with my neighbor because his dogs poo where they shouldn't.
Different attitudes towards private property, and manners you should know by the age of nine
You can have Contrasting views about food, politics, education, sex, whatever, but in
the realm of 2D images, where pixels are the only characters that play the game,
if you want to spot a "difference" you've got to look at pixels values.
Of course, I mean the brightness in each one of their channels.
So if you look at this tiny image made of two pixels only, there's a lot of Contrast,
because the two guys here are certainly different.
Conversely, this other picture, mmm not so, right?
Low Contrast.
Back to more meaningful images, you can build Contrast following the same idea:
forcing pixels to be different. How do you do?
Stretching their values apart, i.e. letting the picture fill the entire, available,
tonal range slots.
Mh??
Example: this image doesn't have any true white and black point.
If you push the lightest areas towards white, pull the darkest areas towards black,
and let everything else in the middle fall into its own place in the universe,
you're going to get: more Contrast.
You're making pixels "more different".
And we call this Global Contrast, because:
A) We live in a globalized world,
or B) the Adjustment acts upon the entire image.
Come on.
Now, let's say that we want to focus on just a portion of the image, a circle of this
particular radius.
Same as before, we can inject Contrast pushing the lightest areas towards white, and pulling
the darkest areas towards black - perhaps not completely, with a grain of salt.
We know the trick now – much better than the original.
But what happens if we now uncover
the whole picture?
Surprise surprise, it is a huge mess – and with good reasons: you're feeding the entire
image with food that's palatable only for a very peculiar region of it.
Bad times.
And, of course, if you let the circle visit different "locations", you'll find out that
each one of them benefits from a different adjustment.
Moreover, depending on whether the encompassed region is big or small, even the same location
may require a different adjustment, based on the features included in the circle.
In other words, Localized Contrast is a matter of finding a way to make targeted adjustments
to image regions of specified extent
all over the place
Easier said than done – especially if you think about literally rolling a circular selection
throughout the entire picture.
Which is not at all how ALCE works, but you get the idea.
Time to see the Panel in Action.
You have one main parameter which is, guess what, a Radius, that is to say the Local...ness
of the Contrast boost
If the radius is small, the area of interest is small too, and we talk about a "More Local",
"Less Global" contrast.
Conversely, if the radius is high, the adjustment is "Less Local", and "More Global".
At the extremes, a 1-pixel radius ALCE is very much like, and in some circumstances
even better than, traditional sharpening. And at a full-scale radius, ALCE tends to
Global Contrast.
This is the Intensity of the effect, that you can adjust to taste.
My advice is to play with the Radius while keeping the Intensity at the maximum level:
it helps to assess the Radius that fits your image and your intents.
Then, if needed, you can always dampen the Intensity if it looks like too much.
Now comes FAQ number one – what could "a fitting Radius" possibly mean?
Take this image as an example: do we want a large Radius, a small Radius, or something
in between?
Generally speaking, the Radius must suit the kind of detail you want to boost.
This portrait has appealing features that span some large areas, so if you remember
the circle-of-radius-whatever thing I told you about a minute ago...
It all boils down to finding a Radius that "resonates" with the image features you want
to enhance.
Like so.
If you use a smaller radius, mmmh, it brings to attention tiny features in the skin that
are either distracting or plain ugly when boosted – but hey, you'll be the judge.
Intensity: to taste, I'm loud here for demonstration purposes only.
In this picture, conversely, the main features are smaller, and so should theoretically be
the radius that is going to boost them.
Please note that when I mention "big" or "small", I refer to the radius compared to the actual
image size: if your starting point is a billboard-sized 300ppi image thousands of pixels wide, a radius
of 10 pixels is a tiny nothing.
Downsample to a gallery thumbnail and all of a sudden 10 pixels become quite a lot.
Big or small, relativity is the key word!
ALCE is as easy as it gets in the beginner's hands, but it is a nuclear bomb if you know
your channels blending, masks, colorspaces and the entire, usual color correction arsenal.
I'm not going to cover advanced techniques here because there already is a 90 minutes,
specific, multipart, HD video series that goes through them in excruciating detail:
check that out here, it is a true retouching masterclass, and it's brought to you ALCE
lovers for free.
Yet there's more that I'd like to tell you about ALCE right now.
As a routine, it is incredibly awesome if you apply it in multiple rounds: increasing
the radius, decreasing the intensity.
Uh?
Yeah I know.
This comes from a technique called octave sharpening – a mouthful, but pretty neat
nonetheless.
ALCE 3 features, and automates something equivalent in the Local Contrast domain, so without further
ado, let's press this plus button and oh!
A new handler appears.
You can drag it and you see that a second radius is set.
Mind you, when dealing with multiple radii, auto-preview is disabled, so you have to click
the run button to check the result.
So what's the panel doing?
It applies the first radius, which is the smallest one, at this intensity, then on top
of it, it runs a second extra ALCE round with this other radius, bigger, at this intensity
here.
And you see that the result is different and remarkably interesting. You can add up
to four sliders, and if you want to have them evenly spaced, press the AUTO button – middle
handlers will be automatically positioned. Move one yourself to break the symmetry or
just uncheck the AUTO for full manual control.
You see that the intensities of each round are predefined, but they can be changed according
to your taste, and tests.
Be aware that multiple rounds of ALCE can reach ludicrous levels of contrast pretty
soon if you keep the Intensities high, so my advice is to start low, and then just
play and have fun.
Also note that now the Intensity slider's got a new name, it's Global Intensity; it's
basically mixing the multiple rounds result with the original, unprocessed image.
Octave ALCE, or what you wanna call it, is a relatively new field: I've done lot of
experiments myself in the past, but it's always been like an advanced technique known and
mastered by very few people.
The new Interface of ALCE 3 integrates the multiple rounds routine and makes really easy
to test and tweak it, so I'm confident that Octave ALCE is now ready for the limelight.
You may have noticed, though, that the smallest radius comes first, so all the rounds are
applied in an ascending order.
This leads to the best results in my opinion, but what if you wanna change it?
This brings me to the topic of Preferences, this button here, where you can define the
Panel's settings – on top, the default intensities for each round, then the radii order: ascending,
from smallest to biggest, or descending, the reverse.
At the bottom, live preview – that, again, works only for single radius ALCE.
Besides Preferences, in the footer you can find the product HomePage.
If you're stuck, here's the manual, it opens a PDF that contains basically what I've told
you here, plus it has some real world examples too.
If you need support, or just want to say hello, here you can find me.
ALCE 3 works internally with a C++ plug-in which computes the image data with 32bits
precision, and it also works with 8, 16, and 32bits HDR images, on Photoshop from version
CC onwards, both Mac and PC.
If you want to record ALCE into an Action for Batch purposes, why not, this button does
exactly so.
I hope you'll enjoy ALCE 3.
I've worked on a lot more Photoshop extensions that you can find here on my website.
Thank you for watching,
bye bye.
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