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The Ideal Digital Photographer's Workflow, Part 5
It may be that Stage 1 was all the sharpening you need to do before sharpening for final output. Chances are, however, that that's not the case. You'll find many instances where using the right kind of sharpening can create real drama.
The Unsharp Mask filter is a very versatile tool that can used in conjunction with many of Photoshop's other capabilities to create a variety of special effects. One of the most useful techniques is to copy your base layer, convert it to monochrome (choose Image -> Desaturate, not Mode -> Grayscale; you want to keep the overall image in RGB or Lab mode), and then Find Edges.
You can then blur the result with the Gaussian Blur filter to control the width of the edges and turn the result into a new channel. The new channel can then be used as a selection so that the Unsharp Mask filter gets applied only to the edges inside the selection. I'd give you complete instructions for doing this, but you're better off to simply go to Adobe Studio and download any of the several Actions that do it for you. Better yet, you can pay $19 for a professionally written filter and Action from Fred Miranda called Simple Sharpen that does an even more sophisticated, 16-bit version that stops the Action and gives you suggestions for making other adjustments.
You can get even more versatile and visual controls from several commercial sharpening plugins. In my opinion, it's worth collecting them all, because each produces different effect or has a different range of effectiveness. My favorites are PhotoWiz Focal Blade (see Figure 2) and Power Retouche's PR Sharpness (see Figure 3). You will notice that the interpretations seen in the preview windows for Focal Blade and PR Sharpness are quite different from one another. (A third plugin option for sharpening is the Imaging Factory's Unsharp Mask Pro.)
The resolution of your output device (whether it be offset press, inkjet printer, or the Web) is likely to be quite different from what you've been seeing on screen. That does not mean that you should have done any sharpening that you've done up until now any differently. What it does mean is that if you want the image you are going to finally present to look as detailed as possible, you are going to have to duplicate the image you have created so far and sharpen it just one more time especially for the device you are going to use to present that image. It is a very good idea to rename these images so that version contains the name and resolution of the output device and to then save those images in a directory or CD that is just for images meant to be printed.
There are two ways to accurately sharpen for printed output: experimentally or with Nik Sharpener Pro. To do it experimentally, use the Photoshop Unsharp Mask filter on several sections of the image -- each with different sharpness settings. Use a text layer to annotate the setting for each section. You can then output this "test" print. Use the USM settings that are closest to the best results. If you want to be really accurate, create another grid with settings that are closest to the best results. If you're really organized, write down the best settings for each different size of image that you're likely to produce from a given original file size.
If the above sounds like way too much work, and you figure your time is worth between $79.95 and $329.95, get one of the three versions of nik Sharpener Pro that is best suited to the type of printing you do. This program takes into account both the size of the image being sharpened and the resolution of the image to be output, and then automatically does the sharpening that will produce the best possible result.
If your output is going to be displaying the image on screen, first duplicate the image and reduce it to the size and resolution at which it is going to be shown. At the same time, convert the color from Adobe RGB '98 to sRGB. That will narrow the color gamut to more closely resemble the "average" gamut of color monitors. Now, simply experiment with the USM filter. I usually start with the same settings that I used in the rescue stage, and then keep sharpening until the result just looks either unnaturally crisp or starts to show edge artifacts (halos).
In this article, you have learned that there are, ideally, three stages at which you should sharpen your images: rescue, creative effect, and output. You have also learned the sharpening requirements for each of these stages.
Ken Milburn has been a photographer, both full- and part-time, for nearly five decades. In addition to countless articles, Ken has written 17 books on web design, Flash, Photoshop, and digital photography. His latest book, for O'Reilly, Digital Photography: Expert Techniques, was released in March 2004.
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In March 2004, O'Reilly & Associates released Digital Photography: Expert Techniques.