Exercise: Sharpening For Print
Take an image that you have processed as the reference standard, with some edge detail and some smooth areas but do not apply any software sharpening.
Make three further versions, each with a different degree of sharpening. Make sure that the weakest of the three is quite close in on-screen appearance to the unsharpened original, and that the strongest is noticeably aggressive.
Print all four images at full size. Next, with neutral white lighting next to the computer screen, compare these prints with each other and the 100% magnification images on-screen.
Write down the differences you see.
I always find these sorts of exercises don’t give definitive results unfortunately. I’m never sure quite what to expect but I really wasn’t expecting the printed results I did.
I normally perform any image sharpening in the RAW editor, rather than in the processing pane, so that noise, clarity, vibrance and saturation issues can be addressed at the same time, and I find it preferable to have the image as processed as possible before taking it across. However, for this exercise I opened the image into the processing pane and performed my sharpening there.
The original unsharpened image didn’t look too bad and the printed image was very similar in appearance. When I sharpened by 25% I couldn’t detect any change on-screen and the printed images showed no visible change either. With sharpening raised to 100% the on-screen image showed a marked change in the pixel size (larger) at 100% magnification and the printed image looked sharper in the detail. At 200% sharpening the on-screen image was definitely sharper in the detail at normal resolution, but very pixellated at 100% magnification but the printed image was very much darker, too dark to be acceptable. I tried a fourth sharpening resolution at 130%, but the on-screen image appeared no different to the previous 200% change, and neither did the printed image.
Sharpening always seems to introduce noise, and in this case the amount of noise that was introduced made the image go much darker, a phenomenon I’ve not seen before or not been aware of why it occurred.
I finally processed the image the way I normally would and was able to control the masking, detail masking, radius and the amount of sharpening, much better. This produced an image that I was very happy with, although I perhaps could have added a little more brightness.
Sharpening clearly has beneficial effects on the image, but I also believe that its necessary to perform the sharpening within the RAW editor where better control over a wider range of variables is available to produce the final, optimised image.