Three Stages of Sharpening with Aperture

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.