Quote:
Originally posted by Choder
I've always wondered what would happen if you took a photo of a photo, I'll bet you could make it huge again?
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An analog enlargement of an alalog pic. Yes, of course you can do that, but you'd just be enlarging grain in the photo. And no analog rendition of an analog subject (whether enlarging or reducing) can add detail. In fact, it always costs you detail and is always worse (in the sense of being less accurate) than the original.
As for a digital photo, suppose I shoot a photo of a car, and the license plate is rendered by 500 pixels, allowing me to see the numbers on the plate. Now I drastically reduce the photo so that only 20 pixels are used. I think you can see that you can't render the 6 or 8 numbers in a plate with only 20 pixels (block out 20 squares on a piece of paper and try it). What has been lost is called "information." I think you can also see that if you blow that 20 pixel area back up to 500 pixels again, there will be no numbers there. It will just be a larger illegible blotch. The information is gone.