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Photographic tips

The wonders of sharpening: resolution doubling

Getting photos out of digital cameras with maximum quality means starting with an original image file which seems slightly soft and blurry. Strange, but true. I offer in evidence the below image, taken with my Konica Minolta DiMage A2 camera. This is a two-image GIF animation in optimized 256 colors, shown at 100% pixel size (cropped from a much a larger file), which has no compression artifacts (like using JPEG images might have had).

Take a close look now (it's a 340 Kb file, so it will take some time to fully display):

The soft, blurry version is what I opened in Photoshop CS2 (via Camera Raw). It is what my Konica Minolta DiMage A2 camera "saw" — except that the camera "saw" a lot more than it seems it did. For the crisply detailed version is what I managed to extract from the original file, by a deft use of both the traditional Unsharp Masking filter and, more importantly, the great, new Smart Sharpen filter in Photoshop CS2, which can sharpen without the white halos produced by the crude, old USM filter. (Of course, proper sharpening should always be tailored to the proper output device — which, in this case, is screen display, not printing.)

Take control — and look sharp!

Images from digital cameras fall into two groups: those which have been auto-sharpened by either the camera's JPEG altorithm or in the raw processing workflow, and therefore look real sharp right away, and those which have had no sharpening applied, and which therefore look soft or even slightly out of focus.

Contrary to what may seem sensible and logical, the first is Bad, the second is Good. Why?

Because only images which have not previously been (auto)sharpened can be sharpened under your own deliberate control. All auto-processing of images inside a digital camera (as when it creates JPEG files) or a raw converter means loss of control — which is Bad. And trying to sharpen previously (auto)sharpened images will only result in images with various degrees of horrible-looking artifacts — a technical term for "ugly little suckers".

Finally, sharpening is the very last process, chronologically, which you should perform on your images, right before printing them or exporting them to final display files (JPEG, GIF, PNG).

For maximum image quality, the moral is: always sharpen your images — but do it yourself and do it at the very end.

Never mind the most obvious differences, like the light ropes. Look a the very subtle textures which have been brought out in the wood on the side of the boat and on the waves and foam of the water. These very subtle textures were of course not created "ex nihilo" by the sharpening process, but were in the original raw file captured by the camera's sensors — only they were too subtle to be perceivable. However, my sharpening brought them out of hiding.

Many web reports about the DiMage A2 camera have claimed it produced "too blurry" images. Hah! I bet that most of these reports were from people who didn't know how to properly process their files (and who maybe even worked with JPEGs, not raws). But I marvel at the subtle detail which my DiMage A2 camera can really capture. And the pixel quality, even after brutal amounts of sharpening (in my special algorithm) is excellent — very lovely pixels indeed. (Yes, I am a certified "pixel peeper".)

This same principle holds for all other digital cameras, too, of course, though to different degrees.

Here is my Great Claim, which may sound crazy but which is, I believe, a profound insight: through proper post-sharpening of non-auto-sharpened digital camera files, the perceptual image resolution can be doubled.

Yes. Doubled. That's what I said: doubled!

The key word here is perceptual image resolution — not the mathematical one. The "perceptual image resolution" is the amount of detail we perceive. And that's what really matters, not brute megapixel-numbers.

If my "doubling" estimate is correct (and it is, give or take a few puny decimals), that means that a four megapixel camera's images can — when properly sharpened — yield the same degree of perceptual image resolution as an eight megapixel camera's images which have not been properly sharpened. And so my DiMage A2, with its eight mexapixels, can yield an approximate amount of perceptual image resolution as non-properly-sharpened images from the 16-megapixel professional heavyweight cameras. And those images can in turn . . .

So there. Chew on that one, Phase One.