Preface Real World Sharpening


For the past fifteen-plus years, I've labored in the vineyards of Photoshop, coaxing pixels to do my will. In that time, I've seen huge advances in the handling of tone and color. When I started doing digital imaging, getting the image to look the same on two different monitors was a major breakthrough, and matching the print to the screen appearance was the stuff of which science fiction was made. Nowadays, it tends to be the rule rather than the exception.

We've made gargantuan strides in the handling of tone and color, but when it comes to control of detail, which is what this book is really about, we're still in 1991. It's just about impossible to make two different displays render image sharpness the same way, and predicting print sharpness from the display is an exercise fraught with pitfalls and perils. In fact, we're back in the days of, "If you want to know what it will look like when you print it, print it, then look at it."

As a result, sharpening (and the equally important other side of the coin, noise reduction and smoothing) tends to be an ad hoc practice. We flail around until we get something that looks decent on the display and hope that that appearance will somehow be transferred to the printed piece.

Photoshop CS2 offers many powerful features for handling image detail. But how do you know what to aim for? This book contains a plethora of different sharpening tricks and techniques, but perhaps the most important contribution it tries to make is to provide you with an analytical framework that lets you think about sharpening in a new way. When we sharpen, we have to take at least three things into account:

  • The relationship between image detail and system noise that's imposed by the capture mediumwe want to sharpen image details but we don't want to exaggerate film grain or digital noise.

  • The requirements of the image contentthe wrong kind of sharpening can exaggerate texture we'd rather downplay, or even obscure detail instead of emphasizing it.

  • The needs of the print processwhen we translate pixels into marks on paper (or canvas, or any other substrate on which we care to print) we inevitably introduce some softness for which we try to compensate by sharpening.

    The huge problem is that these needs often contradict one another.

The Sharpening Workflow

The solution is the sharpening workflow. By treating each demand separately, we can assure that all are addressed optimally. To some, this may smack of heresy. Doesn't everyone know that you can only sharpen an image once? I hope that this book demonstrates that multipass sharpening is not only feasible, but optimal. It's simply impossible to address all the conflicting needs of image source, image content, and output process in a single round of sharpening.

That said, multipass sharpening demands care and attention. Blasting images with multiple hits of sharpening can easily create a hideously oversharpened mess, which is why the conventional wisdom dictates that you only sharpen once. The techniques described in this book will allow you to sharpen images safely, and optimally.

The sharpening workflow confers another benefit. By separating sharpening for output from the other sharpening processes, it creates use-neutral master images that you can easily repurpose for different output processes, at different sizes and resolutions.

Sharpening and the Display

One of the hardest sharpening lessons to learn is that what you see on your computer screen can be highly misleading. But the screen display is often all you have to rely on for your judgments.

Some display technologies render images much more sharply than othersthe same image almost invariably looks sharper on an LCD display than it does on a CRT. Display resolution also has an impact. I've gone to some lengths to debunk the polite fiction that computer screens display images at 72 pixels per inch, and have even given instructions that will let you determine the real resolution of your display, which is the one that really matters.

But the most important lesson of all is that good sharpening for print can often look terriblereally, hideously, horribly badon screen. Learning the relationship between what you see on your display and what shows up on hard copy is a vital skill to acquire.

Objective Realities

Some parts of the sharpening equation are determinate. Human visual acuitythe ability to discern fine detailshas limits that are rooted in the physiology of the eye. The same visual properties that we exploit to produce the illusion of continuous tone from dots of four colors of ink also have a direct bearing on sharpening.

Print sharpening is also a determinate process. Any given print process will always translate pixels into dots in the same way, regardless of image source or image content, so for any print process, there's a right answer in terms of sharpening. (Of course, there's also a very large number of wrong ones.)

Creative Capacities

But sharpening is also a creative tool. We use sharpening to emphasize important detail (and sometimes we use blurring to suppress irrelevant, distracting detail), to make a point, to tell a story, to invoke an emotion, to provide an illusion of three-dimensionality in our two-dimensional photographs.

The sharpening workflow has a place for creativity too. But it's important to know when to be creative, and when to go by the numbers!

Who Needs This Book?

If you work with images that are destined for hard copy, and you aren't totally confident about all your sharpening decisions, my hope is that you'll find this book beneficial. No matter whether you make your own prints, send them out to an online printing service, or deliver commercial work destined for offset press, the sharpening workflow can help you get the most out of your images.

This is not a book for Photoshop beginners, but neither is it a book only for Photoshop experts. Some of the techniques described herein use fairly esoteric Photoshop features with which you may or may not be familiar. Don't let that put you off. I've yet to encounter a piece of software that was smarter than its users, and Photoshop is no exception. Almost all the techniques in this book are nondestructivethey don't touch your original pixelsso you can't do any harm to your images by trying them.

How the Book Is Organized

I've tried to present all the information you need to build your own sharpening workflow in a logical manner.

The first two chapters look at the technical underpinnings of sharpening. Chapter 1, What Is Sharpening?, looks at the fundamental nature of sharpeningwhat it does, and how it works. Chapter 2, Why Do We Sharpen?, discusses the need for sharpening, and all the factors we need to address when we sharpen.

Chapter 3, Sharpening Strategies, provides an overview of the sharpening workflow, and shows how it addresses each sharpening phase. Chapter 4, Sharpening Tools and Techniques, is the tactical complement to Chapter 3. It describes the various tools and techniques that the sharpening workflow employs.

Chapter 5, Putting the Tools to Work, shows how to use the tools and techniques described in Chapter 4 to satisfy the goals outlined in Chapter 3 by building a sharpening workflow from initial sharpening, through creative tweaking, all the way to final output.

Chapter 6, Case Studies, shows examples of the sharpening workflow in action, dealing with different types of images from different sources, to demonstrate the flexibility and power the workflow offers.

A Word to Windows Users

This book applies to both Windows and Macintosh. But I've been using Macs for over 20 years, so all the dialog boxes, menus, and palettes are illustrated using screen shots from the Macintosh version. Similarly, when discussing the many keyboard shortcuts in the program, I cite the Macintosh versions. In every shortcut cited in this book, the Command key translates to the Ctrl key and the Option key translates to the Alt key. I apologize to all you Windows users for the small inconvenience, but because Photoshop is so close to being identical on both platforms, I picked the one I know and ran with it.

A Necessary Disclaimer

Much of the material in this book is an outgrowth of work that I did in the process of developing a commercial sharpening tool, PhotoKit Sharpener, from PixelGenius LLC. I'm proud of PhotoKit Sharpener, but while it embodies all the philosophy and many of the techniques I've described here, it isn't what this book is about. I recognize that automated solutions based on someone else's presets, no matter how well thought-out, aren't for everyone.

Image Credits

I'm indebted to Jeff Schewe for the use of his striking copyright image which appears in multiple locations in Chapters 5 and 6, and for his JPEG images in Chapter 2; to Seth Resnick, for the portrait of me that appears on page 94; to Stephen Johnson, for the portrait of me that appears on page 216; and to Christiane Reitz for the scary cat picture featured in Chapter 6. All the other images, such as they are, are my own.

Thank You!

I couldn't have written this book without help. My first votes of thanks go to Pam Pfiffner at Peachpit Press for provoking me into writing the book, and to Thomas Knoll, for creating Photoshop and thereby giving me something to write about.

Victor Gavenda, my editor, made my prose look polished; production virtuoso Lisa Brazieal turned my virtual creation into a manufactured reality; Liz Welch corrected my many typos and inconsistenciesany that remain are entirely my fault. Karin Arrigoni provided the index to make sure that everyone can find the information they need.

Thanks to my pals and partners in Pixel Genius LLCMartin Evening, Seth Resnick, Andrew Rodney, and Jeff Schewe, for being the finest bunch of people with whom it has ever been my pleasure and privilege to work, and for challenging me to put what I thought I knew about sharpening into practice. An even bigger vote of thanks goes to the late Mike Skurski, who passed away in October 2005, and without whom I would never have been able to produce a successful software product. We all miss you. And thanks to the Pixel Mafiayou know who you are!

And as always, I thank my lovely wife, Angela, for being my best friend and partner, for supporting me in all my activities, and for making my life such a very happy one.

Bruce Fraser

San Francisco, June 2006




Real World(c) Image Sharpening with Adobe Photoshop CS2(c) Industrial-Strength Production Techniques
Real World Image Sharpening with Adobe Photoshop CS2
ISBN: 0321449916
EAN: 2147483647
Year: 2007
Pages: 71
Authors: Bruce Fraser

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