six degrees of definition | adding dimension in Aperture 3

Did you see what I did there? I switched separation with definition. Clever huh?

Alright, all kidding aside: this article is about using the Definition brush in Aperture 3. Notice I specified Definition brush and not Definition adjustment — I’ll get to that in a sec.

First, what does Definition do exactly? Well, Aperture’s user manual says You use the Definition Quick Brush adjustment to add clarity and reduce haze without adding too much contrast to the area of the image the adjustment is brushed on. Now that’s clear isn’t it? Clear as in “devoid of haze”…

Purple Haze jokes aside, that minimal explanation really doesn’t do justice to the importance and power of this brush. What it really enables you to do is bring out details in a very targeted manner. The effect of which is a sort of sharpening but without the abruptness. Essentially we’re talking about micro contrast, which in Nik parlance would be Structure and in Adobe’s Lightroom Clarity. While each have their own specific effect, their overall goal is the same: increasing the illusion of focus and dimension.


Taken to extremes Definition can get seriously tacky. You know: bad HDR tacky. So its strength — IMHO — resides in how it’s used. Also, If you’re expecting to bring an out of focus part of your image back into focus, forget it. It will look bad and artificial, especially under close examination.


You’ve probably seen (and used) the Definition slider that’s part of the Enhance brick. It’s just a simple slider that controls the amount of Definition you wish to add. It’s also a global adjustment, unless you choose to paint in the entire brick — but you’re then bundling all the Enhance adjustments in a single mask which may or may not be the best solution.

While I sometimes use that Definition slider for a minimal amount of punch on certain images (BW pictures usually gain the most from this), I’ve developed a workflow that pretty much exclusively uses the Quick Brush version. There are three very important reasons for this:
1) On the brush you also get Radius control. This is huge. More on this coming up.
2) With the brush you can have multiple instances of Definition — and only Definition.
3) It goes to eleven. No seriously, it has a higher strength value.


If you’ve read some of my other Aperture tutorials you already know how important multiple instances are to my workflow. In case you haven’t, here’s the gist of it: Aperture 3 allows all of its adjustment bricks (except obvious ones like Exposure, RAW Fine Tuning, crop etc) to be duplicated. You do this by clicking on the gear or cog icon on the brick itself and choosing Add a new whatever-brick. This opens up tremendous possibilities as it effectively creates layer masks and allows you to control where and how adjustments will be applied to your picture.

With this in mind, take a look at the following picture of your’s truly:

Nothing wrong with it. Good focus, reasonable sharpness and detail. Weird looking guy but whatev… Done.

Not so fast.

Looking at this picture I know certain areas will benefit from added Definition. I also know that it won’t be one size fits all. So let’s add a first Definition Quick Brush. This will be my micro details brush.
Wait, what? Right… I need to talk about radius.

As I said earlier, the advantage of the Quick Brush version over Enhance is the added Radius control. It defines the spread of the effect, which in real life means the size of the details that will be affected. For example, accentuating pores on the skin or grain in metal: small radius. Making clouds look more intense: larger radius. This is something you’ll have to play around with but eventually you’ll start knowing instinctively what to use. And it’s a slider so… fiddle with it.

I’ve developed a certain routine for adding definition. I usually start off with an instance that has a very small radius, add a second with a larger radius and sometimes finish off with very slight punch of the global Enhance brick Definition. The key is to identify what areas will benefit from each instance. It’s all about zones. But there’s one rule as far as I’m concerned: do not touch out of focus areas. The idea is to enhance what’s already there, not invent focus.


So here’s my first Definition instance. I’ve set the radius to 7.84 and the strength to its maximum of 2 in order to really see the effect while I’m painting it in.

Btw, If you’re new to Aperture 3 and are wondering how to get that slider to go past 1: it doesn’t. To get higher values you need to place your mouse in the value box and drag left or right (yes, some bricks - like White Balance - go below minimum as well). Not intuitive in the least but until Apple changes it, that’s how you do it.

I’ve decided to apply the brush to the glasses, eyelashes and a tiny bit of hair. Here’s the resulting mask:

And here’s the picture after adjusting the strength slider. It’s subtle but it’s definitely (Ha!) there.

I now create a new instance of the Definition adjustment and set its radius to 30. Same deal with the strength slider. This time I apply it to the folds in the hoodie. Here again is the mask:

And the picture:

Bonus tip: You can use the Apply to Entire Photo menu item in the Quick Brush to get a quick preview of an adjustment and identify which areas will benefit from it. Sometimes you’ll even realize it might be easier to just brush away the effect. There’s no right or wrong way here.

This time I think I'll also add a tiny bit of general definition as well, using the Enhance brick.

And just to give you an idea of the importance of using the right radius in the right area, here's the same picture with reversed radius settings:

Notice how dark the eyelashes are. I know the web version probably doesn't do it justice but experiment on your own and you'll see what I mean.


Beyond providing some added punch, the use of Definition is another way of creating drama and dimension in a picture. It can also force the viewer into perceiving a photo differently by leading the eye in a certain way. The difference is often barely perceptible and yet…

I leave you with a few more before and after examples.