Tips & Tricks - What's Wrong with the Sharpen Tool?

I've been using Photoshop for many years. I've written articles and recorded over 30 minutes of video on the subject of sharpening using the wealth of excellent sharpening techniques Adobe provide, so I figured I'm qualified to bring up one of the most negatively discussed and ubiquitously bemoaned tools in the existence of image editing, that's right - not just Photoshop but the whole image editing world - the Sharpen Tool. Here I plan to explain what its purpose is, what it really does do, and when and why it might come in useful.

Every image that's taken on a digital camera requires some form of sharpening, either inside the camera itself (especially relevant if you're shooting to JPEG) or in post processing using RAW files. For those not in the know, sharpening is the name given to a technique that appears to bring the image into tighter focus, just not by traditional means. There's no way of really adjusting the focus of a soft image once the photo has been taken so Photoshop has been trained over time to fake it. Instead of adding real detail, it simply adds more contrast to perceived edges in the image. It makes the lighter side of an edge lighter still, and the darker side darker still making the human eye believe it is seeing a better focused image, where as in reality it is simply seeing an image with a higher degree of contrast along the edges. This process is known as sharpening. To see a demonstration of how we pull this off, and how it works, check out my video tutorial on Basic Sharpening.

 

 

Now to answer the question. The sharpen tool allows us to paint in sharpness using a variation of the brush tool. The only thing is it doesn't work very well.

The real problem with this tool, in my humble opinion, is that there's no preview and no way of measuring how much sharpening is being applied. Take the image I've included to the right as a classic example of what the Sharpen Tool leaves behind - a random although very pretty mess! That's not desirable on artwork, and it's not setting a very high standard for photographic adjustments either, after all, adjustments are intended to make the image look better, not obliterate it.

 

Now I shouldn't leave you with the impression its all bad news. It's not. There are some circumstances where the Sharpen Tool can come in helpful, in its own charming way.

If you do plan to make use of this tool I'd recommend becoming accustomed to the strength option it offers in the options bar when the tool is active. 50% is the default value but I've found this to be too strong. Best take it down to between 10-30% and then practice practice practice. If you're using a pressure sensitive tablet then make sure you have the pressure sensitivity set to something you can work with, like I said, it will take some getting used to but if you're willing to stick at it you will reap the rewards.

Most of the artistic tools (blur tool, smudge tool, burn tool, and sponge tool) don't offer previews either; it's hard to when using a brush and sometimes defeats the purpose of the tool in the first place.

 

If you want some examples of when and where to use this tool I'd reply 'eyes'. Again, I tend to use more traditional sharpening methods but if you're in a hurry, or you've learned to own the tool, a quick click at a low strength setting can bring the eyes in a portrait shot to life. Try it yourself, but please remember to inspect the results with a high zoom ratio, too little and you'll see no benefit, too much and the eyes will appear brittle and far to crisp.

Yes. To create noise. Now that may seem like a strange use for a tool that's intended to make things clearer and sharper than before but as my demonstration testifies - if you crank up the strength you can get a rather cool noise effect. Now I'm not trying to convince you for a second that noise is going to improve images, but it can be a creative way to add an artistic effect of your own instead of using the Add Noise filter.

 

Anyway, that's my hopefully well-balanced view of the Sharpen Tool. I hope you now understand the perils and even positives of employing this tool into your own projects.