Posted by Elizabeth on 12/06/05 10:46

"Onideus Mad Hatter" <usenet@backwater-productions.net> wrote in message
news:5m67p15cdtbapilvd39kilrgpgkfvi9d1u@4ax.com...

> Apparently Oldami is the kind of dumbass who thinks you can resize a
> raster image to any size and it'll retain the same quality. Free
> cl00, kiddie, even if you up yer res, it's still 72 pixels per inch,
> altering the res essentially just changes the size of the pixels, but
> it's STILL 72, you fucking moron. What, do you think your computer
> can just MAKE UP pixels that don't exist? LOL

Your *computer* can't do much of anything. But your computer, running
Photoshop, most certainly CAN, and DOES, "make up pixels that don't exist."
Just what is it you think is happening when you "upsize" an image ?
Depending upon who you care to listen to, the process is known as
extrapolation or interpolation (interpolation is probably the more accurate,
though perhaps less intuitively correct, term) and what's going on is that
PS, though the use of some fairly sophisticated linear sampling algorithms,
is essentially making guesses/approximations on what pixels WOULD be in the
gaps created by expansion of the image boundaries had such been of the
target bounds originally.

If you think about the problem, you'll understand why degradation, while
inevitable, is really quite variable, depending upon the nature and density
of the source information, choice of algorithm, and extent of interpolation
... moreover, if you think beyond PS, there are more sophisticated signal
processing systems which can do an even better job of "making up pixels" ...
not a knock on PS ... but as good as it is, it's still a mass market, albeit
professional grade, product that has to run on all kinds of off-the-shelf
hardware configurations ... high end medical imaging systems, for one, have
no such constraint and can use adaptive interpolation techniques with even
better results .. but that stuff requires a LOT of processor cycles

You need to think about PS and related processes (printing) in more
operational terms. You have a lot of energy; it's just a little unfocused.

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