When I look at a small image, I can see what it is. If I blow the image up, for some reason the perception of what it is gets muvh worse. This is true of Windows icons, for example, and especially true of reduced text that just looks random if you enlarge it.
A similar phenomenon happens with some optical illusions where you have to squint, or hold the picture at arm’s length, or even across the room, to see what it is.
Why would something become less clear when you get more information? (I know, blowing up a digital image does not give you more information, it just makes the existing information bigger–but it doesn’t look like the same thing only bigger, it looks like a blur.)
Basically, human vision is oriented around picking up on lines or line detection, and it’s quite good at interpolating the missing or jagged parts of lines if they are small. However, as it gets bigger, your brain does less filling-in and actually looks at what’s presented on the screen, a bunch of square dots that come together to look like something.
So, when it’s small, your brain fills in the missing info, but at large sizes, it stops doing so much. That’s why, for me, going in any closer than 100% on a computer image can actually “show” less information than a zoomed in one. Hope this helps and is a little less glib than Reeder’s.
But blowing it up does give you more information. All the straight lines or pixel artifacts that were lost near the ability of the human eye to resolve become impossible to ignore when you enlarge a chunky image. The brain likes to interpret images as smooth objects, but it doesn’t automatically reduce acuity to achieve that end.
Thanks, Squink, that link is exactly the phenomenon I’m talking about and I think your explanation is quite sane. Close up that image looks like nothing in particular but across a room it’s Lincoln, no two ways about it.