More on Sharpening in Adobe Lightroom 3
In the theory of sharpening, the process can be broken down into three phases: capture sharpening, creative sharpening, and output sharpening. Last week I covered sharpening in the Develop module which is the primary tool for sharpening and can handle all three phases, but Lightroom also has dedicated tools for sharpening in the Import dialog of the Library module for capture sharpening, as well as in the Print and Web modules for output sharpening.
Sharpening During Import
Digital image capture is an inherently lossy process. Reality has to be forced to fit within the confines of your pixels and how they see the world. And since each photosite on your camera's sensor only sees one primary color rather than all three there is even more loss. Fully two-thirds of your eventual image has to be guessed, or "interpolated" based on data that was captured. If a given photosite is sensitive to red light, the green and blue values that will be used to render that pixel have to be approximated from neighboring pixels. The algorithms used to do this are quite sophisticated, but still involve a lot of guess work, even if these could be legitimately described as educated guesses. Capture sharpening aims to restore some of the softness caused by inherent limitations of this technology.
To get new images into the Library module in Lightroom, you have to import them. When you do, the dialog gives you the opportunity to apply a set of pre-saved Develop settings. These settings can include color correction, black and white conversion, adding film grain, vignetting, or just about anything you might want. If Lightroom doesn't come with a preset to do what you want you can save new presets. In my opinion, most of these sorts of edits are better made directly in the Develop module, but one type of change worth considering during import is sharpening. Specifically, I'm referring to capture sharpening.
Lightroom comes with two presets for sharpening: "Sharpening – Narrow Edges (Scenics)" and "Sharpening – Wide Edges (Faces)." In an unusual twist, these names are actually fairly descriptive. If you are importing a batch of images (such as scenics) that contains a lot of detail you want to render clearly, choose the former. If you have a batch of images (such as facial portraits) that should clearly show major edges but might yield unflattering results if every imperfection shows, choose the latter. If over time you don't find either of these to your liking tweak one or the other and save it as your own Develop preset.
Regardless of how you sharpen a batch of images during import, keep in mind that Lightroom never actually changes your actual image data. Whatever choices you make at this stage remain freely editable later on when you optimize each image in the Develop module. Think of sharpening during import as a time saver to get you in the ballpark. You're not locked into anything.
Sharpening in the Print and Web Modules
After you spend time making an image look its best in the Develop module, you have to print it or export it to some format that allows you to share it with others. Unfortunately, both of these are inherently lossy processes, just like image capture. There is a degree of softening that happens during printing or saving a file to jpeg or other similar formats. Output sharpening aims to mitigate this loss, and Lightroom helps you do this with tools provided in both the Print and Web modules.
Sharpening in the Print module takes a different approach from the way sharpening works in Develop. Gone are the sliders for such abstract variables as "Amount" and "Detail." In their place are settings for Media Type as "Glossy" or "Matte" and whether you want "Low," "Standard," or "High" sharpening. Together with the selected Print Resolution in pixels per inch, Lightroom can then use these choices to calculate the sharpening needed. Note that your choice of paper type here is independent from the paper type selection in your printer driver, but generally both should be set the same. If you select "Draft Mode Printing" print sharpening is disabled.
One thing that is missing from Print module sharpening is the ability to preview what you will end up with. It would be nice if Adobe provided a window to see how your choices will affect the results, but this would be difficult since so much depends on your particular printer and paper choices. You will need to figure out what works best for your own needs. One way to do this would be to put together a test file that represents the variety of what you normally print and print it with various choices. You can use one of the print package templates to easily print a selection of images at the same time. After printing, you can set the resulting pages side by side for comparison in detail.
Lightroom also lets you "print" to a jpeg file via the "Print To:" drop-down box at the top of the Print Job settings. Media Type isn't relevant in this case so Lightroom disables that selection.
Sharpening in the Web module is even simpler. Under Output Settings, all you get is a dropdown selection for "Low," "Standard," or "High." Lightroom handles the rest for you.
Keep in mind that you don't have to apply any sharpening in Print or Web. In fact, if you sharpen in the Develop module with your target output media in mind, you probably don't want to duplicate that in Print or Web. The choice of what you use is up to you.