10. Sharpness, Detail, and Noise Reduction

The human visual system depends to a great degree on recognizing edges. Our eyes pass information to our brain, where every detail is quickly broken down into whether it is or is not an edge. (Millions of years of evolution have developed our brains to ignore most of what’s going on in our field of vision and instead focus immediately on moving edges that might turn out to be a hungry tiger.) An image may have great contrast and color balance, but without good edge definition, you simply see it as less lifelike.

No matter how good your camera or scanner and how crisp your original may be, you always lose some sharpness when an image is digitized. Images from scanners and digital cameras always need ...

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