The vast majority of photographic images benefit from sharpening. Before you decide how and when to sharpen images, you need to decide why you’re sharpening them. The goal is to enhance detail rendition without producing distracting visual artifacts. You’ll find many conflicting philosophies and their accompanying strategies for sharpening images. The seemingly conflicting advice can be hard to reconcile.
Should you sharpen once or multiple times? Should you sharpen differently for different subjects? Should you sharpen differently for different sizes? Should you sharpen differently for different presentation materials or supplies? Should you view your files at 100% or 50% screen magnification?
Capture source, output device, substrate or presentation device, presentation size, subject and artistic intention all play a role in sharpening. The characteristics and solutions for many of these factors can be objectively defined for everyone; at least one of these factors—perhaps the most important, your artisti vision—only can be decided individually.
So, if sharpening is a complex subject, how do you simplify your sharpening workflow to one that’s practical without compromising quality?
Bruce Fraser and Jeff Schewe offer the best advice in their definitive volume on sharpening, Real World Image Sharpening with Adobe Photoshop, Camera Raw, and Lightroom, which is highly recommended reading for every photographer. Instead of sharpening your images for you, they teach how to sharpen.
Their philosophy of sharpening is perhaps the soundest in the industry. They recommend that images be sharpened in a progression of three stages: once for capture sharpening, a second time for creative sharpening, and a third and final time for output sharpening. The objectives and methods of each of these stages vary considerably. When mastered, the whole process can be streamlined to achieve sophisticated results in minimum time.
Capture sharpening is something almost all images can benefit from. It compensates for inherent deficiencies in optical and capture systems. All lenses and sensors have deficiencies. They don’t all have the same characteristics or deficiencies.
General parameters for ideal sharpening settings can be determined for all images created with the same lens/chip combination. You can speed your workflow by determining settings for a best starting point. You may need to modify these settings somewhat to factor in additional considerations, such as variances in noise (ISO, exposure duration, temperature), noise-reduction settings and the frequency (or frequencies) of detail in an image.
Capture sharpening needs to be determined visually, while previewing an image on a monitor at 100% screen magnification, the magnification that most precisely displays low-frequency detail such as texture and noise.
Capture sharpening is best done during RAW file conversion. It must always be done after scanning of analog originals.
Capture sharpening typically is done globally and uniformly to all areas of an image, but on-the-fly masking routines are recommended to reduce or remove sharpening effects from low-frequency (smooth) image areas.
When performing capture sharpening, err on the conservative side and avoid producing unwanted artifacts. Don’t fall prey to the temptation to fix unwanted sharpening artifacts you could produce at this first stage of sharpening in subsequent stages of image editing; you’ll get better results if you don’t produce unwanted sharpening artifacts at all.
Noise-reduction practices will impact sharpening practices; reduce noise before sharpening.
Creative sharpening is potentially the most high-impact stage of sharpening. Even so, not all images need to be creatively sharpened. In high-productivity workflows, this stage of sharpening is typically abandoned, as it can’t be automated. Creative sharpening is generally reserved for images that merit additional care and consideration. The decisions made at this second stage of sharpening largely are subjective and based on the visual preferences of the individual doing the sharpening, not the characteristics of the tools used to produce an image.
The goal of creative sharpening is to give an image a specific look and feel. Creative sharpening can prioritize image information, guiding a viewer’s eyes in more specific ways, and enhance qualitative aspects of images to produce stronger responses. Used consistently, creative sharpening can produce a distinctive style to viewers. (Creative blurring also may be used in combination with creative sharpening to make the effect seem even stronger by comparison.)
Creative sharpening is done after RAW conversion (or scanning), typically in Photoshop, employing additional image layers to produce the most sophisticated results. Creative sharpening is most frequently applied selectively, varying the amount and/or type (Unsharp Mask, Smart Sharpen, High Pass, etc.) of sharpening in different regions of an image.
Capture sharpening needs to be determined visually, while previewing an image on a monitor at 100% screen magnification, again, the magnification that most precisely displays low-frequency detail such as texture and noise.
Creative sharpening may need to be removed and reapplied if an image file is dramatically up-sampled, as the resampling process can make sharpening artifacts not visible at smaller scales more pronounced at larger scales.
When performing creative sharpening, there are essentially no rules. Only the image source and the software you use to enhance it will determine the limits of how far you can go. If there are limits to how far you should go, those limits are only determined by consensus; in general, most viewers don’t want to be distracted unnecessarily by sharpening artifacts—unless they’re presented for a good reason. During creative sharpening, you can leverage any and all sharpening techniques. Creative sharpening can be as simple or as sophisticated as you choose or are able to choose. Increasing your skills will lead to enhancing your expression. The final determining factor during creative sharpening is that it creates a desired visual appearance.
Output sharpening benefits printed images. Images intended for display on monitors rarely need to be sharpened for output, unless they’re substantially resized. Output sharpening is intended to compensate for image softening due to characteristics of the output device, such as dot gain on inkjet printers, and varies with both the type of printer and substrate used and, in some cases, environmental factors such as humidity. Output sharpening typically also factors in 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 is best done when viewing images at a screen magnification of 50%, the screen magnification that best displays medium-frequency detail such as contours. Previewing an image at 50% m
agnification is an imprecise, but practical way of compensating for the differences in between display (so many phosphors or diodes per inch) and printer (so many dots per inch, 2880 for Epson printers). 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 and on varying substrates. Checking a file at 100% magnification for unwanted artifacts in high-frequency detail is recommended before committing to print.
As previewing output sharpening on monitors is imprecise, precise output sharpening must be confirmed with printed samples. The settings used to achieve optimum results in a representative image or selection of images then can be used for all images printed to the same output conditions. Output sharpening can be automated.
There are many competing solutions for output sharpening; automate it in Lightroom; automate it in Photoshop with plug-ins like Nik Software’s Sharpener Pro or Pixel Genius’ PhotoKit Sharpener; automate it with your own Actions in Photoshop. Using a preexisting solution reduces the testing necessary to create your own and brings to bear the expertise of experts in the field in your images. Though each solution requires a little testing before implementing, any one of them delivers better results than not performing output sharpening.
Output sharpening is one of the last things, if not the very last thing, you do to enhance an image file.
While there’s an ideal three-stage sharpening workflow, there’s no one ideal magic setting for sharpening all images. Many considerations must be weighed throughout the process. So, if anyone ever asks you, “What are the ideal settings for sharpening an image?” quote Jeff Schewe: “ƒ/8.” In other words, there are none. While some parts of the process can be automated, others cannot. You have to use your eyes and make some decisions. The more educated you are about what to look for in images and how to use the tools you make them with, the better the chances that your images will look the way you want them to look. You even may learn to see more clearly in the process. Sharpening images is both a science and an art.
What To Look For When Sharpening
Try to maximize:
Try to minimize:
In most cases, you want to produce a compelling appearance without producing artifacts that are distracting to the visual experience.
Depending on how it’s applied, sharpening can enhance or reduce the perception of clarity, texture, depth, contour, tone, saturation and relatedness between elements, as well as produce a variety of energetic qualities all of which may lead to a variety of emotional associations on the part of the viewer. Sharpening should clearly present your relationship to your images and subjects. Sharpening will change the way people view your images and their responses to them. Sharpening not only is a technical consideration, but it’s also an aesthetic one.
John Paul Caponigro, author of Adobe Photoshop Master Class and the DVD series R/Evolution, is an internationally renowned fine artist, an authority on digital printing and a respected lecturer and workshop leader. Get over 100 Lessons with his free enews Insights at www.johnpaulcaponigro.com.