Laura Shoe created a helpful blog post for Lightroom users in which she discussed Lightroom’s approach to sharp­ening. In many ways, Aperture handles image adjust­ments much like Lightroom, but they do differ a fair amount in how they deal with sharp­ening. This article is intended to “translate” Laura’s discussion for Aperture users. And I’ve written about sharp­ening in Aperture before, so you may want to check that out first.

Laura points out that many follow the advice of Bruce Fraser and Jeff Schewe in their book Real World Image Sharpening and apply sharp­ening in three stages: Capture, Creative and Output. Capture sharp­ening is used to offset the inherent blurring effects of digital capture devices such as cameras and scanners. Creative sharp­ening lets the image adjuster make overall, or more commonly localized, sharp­ening changes. The last step, output sharp­ening, is done at output and should take into account the output medium, the output device, as well as the intended viewing distance.

The RAW Fine Tuning Adjustment Brick

Capture Sharpening

These concepts apply equally to any image adjustment software. It is the execution that is different. Let’s start at the beginning of the process with capture sharp­ening. Aperture’s capture sharp­ening is done in the RAW Fine Tuning adjustment brick.

You’ll see the two control sliders. Sharpening (how much of a sharp­ening effect should be applied) and Edges (what in the image should be considered an edge and be sharpened). A setting of 0 Sharpening creates no sharp­ening while a setting of 1 provides the maximum effect. For Edges a setting of 0 means nothing should be considered an edge and 1 means almost every­thing is an edge and should be sharpened.

Something to note here is that Aperture is very gentle in its appli­cation of sharp­ening in general. And this is espe­cially true of RAW Fine Tuning sharp­ening. Its a very subtle effect. Also true is that sharp­ening effects are best viewed at 100%—so use the loupe or the Zoom To Actual Size commend in the View menu.

Because capture sharp­ening is meant to offset the soft­ening effect of the image capture device, one set of sharp­ening para­meters will be “right” for any given device. Aperture lets you set those para­meters as defaults for each device inde­pen­dently by using the Save As Camera Default command under the gear menu of the RAW Fine Tuning adjustment brick.

Creative Sharpening

The Edge Sharpen Adjustment Brick

First a comment. Aperture version 3 offers two adjustment bricks for creative sharp­ening—Edge Sharpen and Sharpen. The Sharpen brick is left over from earlier versions for compat­i­bility, but I advise against using it because the Edge Sharpen brick is so much better and more powerful. Forget there is a Sharpen brick.

The Edge Sharpen brick offers three control sliders. Again there is the Sharpening slider as well as the Edge slider. Both work the same way as the matching sliders do in the RAW Fine Tuning brick. But now there is the added slider for Falloff (the amount of sharp­ening done on the second and third of Aperture’s three pass sharp­ening tech­nique). A setting of 0 Falloff means that no sharp­ening is applied during the second and third sharp­ening passes while a setting of 1 means that 100% of the first pass sharp­ening effect is applied on the second pass and 100% of the amount of the second pass is applied in the third. This is pretty clever because a setting on 0.5 means that 50% of the first pass sharp­ening effect is applied on the second pass and 50% of the amount of the second pass is applied in the third. Said another way, the third pass would use 25% of the first pass effect.

Output Sharpening

Printers and paper will both cause a slight blurring of the image on output . Also, images are meant to be viewed a different distances; you’d rarely expect someone to look at a 30″ x 40″ print up close, but a 3″ x 4″ web image will be seen from just a foot or two. Therefore some sharp­ening is often needed at this stage.

The Image Adjustment Brick of the Print Dialog

Aperture has an Image Adjustment brick in the print dialog box to control print sharp­ening. Unfortunately it does not have sharp­ening controls in its export controls.

For printing the sliders change names to Amount (just like the Sharpening slider else­where) and Radius (the distance, in pixels, that Aperture uses to evaluate sharpness). Frankly, it makes no sense to me that the print sharp­ening controls should be named differ­ently and have different effects than in the Edge Sharpen adjustment brick.

Here a setting of 0 for Radius means there will be no sharp­ening while a setting of say, 3 would mean that sharp­ening would be applied up to 3 pixels away from an edge. If you want to judge the sharp­ening effect on screen, use the loupe tool next to the Amount and Radius sliders.

If you want to apply sharp­ening for exporting files formats such as JPEG or PNG, you’ll need to get the free export plug-in BorderFX. It, too, has Amount and Radius sliders.

In General

Sharpening is a very subjective adjustment, and double so for capture and creative sharp­ening. So you’ll have to apply the effects to your own taste an creative vision. But a good thing to remember is that less is often more for sharp­ening. Don’t over do it. And Aperture will help with that as all of its controls, but espe­cially its RAW Fine Tuning sharp­ening, are subtle.