Sharpening Images With Photoshop

This article was originally posted in response to a query on the Nature Photographers Network web site with regard to “capture sharpening”.

Being new to digital photography, my post prompted some educational responses. I’ve included some links to books and articles at the end of this post that I found with some follow-on research. I should point out that the most significant information information about sharpening workflow is that it is typically broken up into three parts:

  • Input
  • Creative
  • Output

The bulk of this article is about “output” sharpening.

Anyway, I had read a few articles about sharpening images in Photoshop recently and while they were very helpful in figuring out how to use the sharpening filters available in Photoshop, I found that making an adjustment to my workflow had the biggest impact in the final output.

As I’ve become more serious about my photography hobby recently, one of the biggest issues I’ve struggled with is sharpening images for web consumption. I see thousands of marvelous images every week and felt like mine didn’t compare in terms of clarity, which seems like a pretty basic attribute of a good landscape photograph. I had assumed that because I wasn’t using professional equipment I just wasn’t going to get the clarity I wanted. While that’s probably still true, I’ve found that for the web, I can work around that.

My workflow had been to use the “Clarity” control in the ACR (Adobe Camera Raw) utility then as soon as I open the image in Photoshop sharpen it. The “Clarity” control made discernible changes to the image whereas the Sharpening did not. This worked better than not sharpening but when I reduced the image size and exported it as a JPEG, it didn’t look great; just “better” than they did as a RAW image file.

(The term “capture sharpening” or “input sharpening” refers to using the sharpening controls in ACR to sharpen the RAW file. This sharpening is subtle, requires viewing the image at full resolution.)

I decided to experiment with the steps I used and some of the settings applied. What I came up with is using a different algorithm for sizing down and doing the sharpening after all other adjustments are done and before I export as a JPEG.

The last couple of steps that I use are:

  • Flatten the image
  • Resize the image (select “bicubic sharper” from the dropdown menu)
  • Change the Mode (under the “Image” menu) to “Lab”,
  • Click the “Channels” tab and select the “Lightness” channel
  • Apply the sharpening filter
  • Change the Mode back to RGB
  • “Save-As” a JPEG

The sharpening filters are under the “Filter” menu item in Photoshop. I typically use the Unsharp Mask filter (amount 100-300 [depending], radius .5, masking: default). Sometimes Unsharp Mask seems to be a big harsh so I use Smart Sharpen (amount: 100, radius .5, select “Remove Gaussian Blur” and check the “More Accurate” box). If I’ve sharpened in an earlier step, I will use only Smart Sharpen but put the level at 30-50. Sometimes there will be a bit too much sharpening, so after using one of the sharpening filters, an option becomes available under the “Edit” menu that allows you to “fade” the effect; I usually set that to 50-90. Note that for all sharpening I have the “Lightness” channel selected and that includes when I use the “Fade…” feature.

After I’ve done the sharpening, I press “ctrl+shift+~” which switches on all channels and turns the color back “on”. If I see that I need to adjust the sharpening, the I can press “crtl+1” to select the “Lightness” channel again. Then I’ll either readjust the sharpening or take the “Fade Unsharp Mask” route described above.

I have found that by doing all color and tone adjustments, resize, then sharpening at the very end of post, the results are far, far better than when I was sharpening at the beginning or middle of processing.

Note that saving as a JPEG for the web can ruin the sharpness so you’ll need to experiment to get everything setup just right for great web images.

The most informative article I read was one by Bruce Fraser here and a more recent follow-on article by Conrad Chavez, here.

Also Bill Pelzmann from NPN who is substantially responsible for my new understanding of the art of sharpening recommended Real World Image Sharpening with Adobe Photoshop, Camera Raw, and Lightroom (2nd Edition).

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