Output Sharpening

March 29, 2012 | Leave a Comment |

Image source, frequency of detail, subject, personal preference, output device, substrate or presentation device, and presentation size all play a role in sharpening. The art of sharpening gives you precise control over various image characteristics—contrast, saturation, contour (halo and line), texture and noise. It’s best applied in three stages: capture, creative and output.

While there’s an art to sharpening, which provides extraordinary creative freedoms, some aspects of sharpening are best automated, such as output sharpening.

Output sharpening is used to compensate for the softening of detail that a specific device produces. Ink on paper, whether applied with an offset press or an inkjet printer, is notably susceptible to this. When drops of ink hit paper, they deform on impact and spread more or less based on the absorption characteristics of the substrate. This is called dot gain; the dots gain size. Dot gain varies with the type of printer, ink and substrate used. It also can be impacted by environmental factors such as humidity. Output sharpening typically also factors in file resolution and the scale of the final product, which is used to determine an ideal viewing distance—though the actual viewing distance is usually variable.

Output sharpening primarily benefits printed images. Projected images also can benefit somewhat. Images displayed on monitors rarely need to be sharpened for output, as they’ve already been sharpened based on the display device, during capture and creative sharpening.

There’s always a mismatch between the quality of image detail when displayed on a monitor and when printed. Comparatively low-resolution monitors can’t precisely preview what a print will look like on a high-resolution output device, much less precisely preview detail on many different output devices, with varying resolutions or on a variety of substrates with varying amounts of dot gain. So, the image on screen only can approximate, but not precisely display, the sharpness of the printed piece. (In the future, we expect algorithms to be devised to simulate this on screen.) In the end, you make the image on screen look too sharp, knowing it will soften when printed. How sharp do you make it? It depends on your printed proofs. You have to test various sharpening settings, make test prints and compare the results to determine optimum sharpening routines for a given printer and substrate combination. In addition, you should factor in the scale of the final printed piece.

Once determined, the settings used to achieve optimum results in a representative image or selection of images then can be used for all images printed with the same output conditions. You can write an Action to perform an optimum sharpening routine repeatedly. In short, after some initial testing, output sharpening can be automated.

Output sharpening can be complex and tedious. Most photographers would do well to enlist help from the experts to get the job done. There are many competing solutions for output sharpening; automate it in Lightroom or automate it in Photoshop with plug-ins like Nik Sharpener Pro or PixelGenius PhotoKit Sharpener or your own Actions. Using a preexisting solution reduces the testing necessary to create your own settings and brings to bear the considerable knowledge of experts in the field to your prints. Though each of these solutions requires a little testing before implementing, any one of them delivers better results than not performing output sharpening.

Pixel Genius’ PhotoKit Sharpener

NIK’s Sharpener Pro

Lightroom 4 Print Module

Until there’s a truly objective way of determining output sharpening, you’ll have to do a little testing yourself, but the amount of testing you’ll need to do will be minimal when you use automated solutions. Why do automated solutions require a little testing? Because individuals, no matter how objective they try to be, have preferences for image sharpening characteristics, which may or may not mirror your own preferences. They have to make judgment calls and so will you. But when testing their solutions, your task is much easier. You simply raise or lower the opacity of the sharpening layers their routines create, make test prints, determine your preferred opacity, and use that setting for all of your prints. (In Lightroom, you test the four settings: None, Low, Medium and High.)

Output sharpening is the second to last thing you do to enhance an image file before printing it. As a final step, you’ll probably want to carefully inspect an image at 100% magnification to make sure sharpening hasn’t accentuated any minor flaws. If it has, retouch them. And print.

Almost all images can benefit from output sharpening. (Notable exceptions are images with extremely smooth or low-frequency detail, such as minimalist soft-focus fields.) With a little testing, you can determine optimum output sharpening routines for your images and taste, and automate the process, saving you time and delivering better and more consistent results.

What do I use for output sharpening most often? Lightroom.

You can find the do-it-yourself output sharpening routine I recommend on Digital Photo Pro.

Find more sharpening resources here.

Learn more in my digital photography and digital printing workshops.

Category: Sharpening
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