Troy Piggins <usenet-0805@[EMAIL PROTECTED]
> wrote:
> I've had a bit of an edit of it. It's 3504x2336px full size, the
> crops are smaller obviously.
> I understand that photo quality prints are around 300ppi,
That's for 4x6 (where you get up close to see every detail)
and other formats where you want to get *really* close up.
Posters usually work out well at 150dpi --- many printers
(posters are printed, not exposed (e.g. by a laser) and
chemically developed) can't do more.[1]
Canvas has a surface structure. That structure also limits how
close you can come to the canvas and expect additional details.
> But I think he really wants this thing blown up, like 1 metre
> wide or something. I'm concerned it may come out pixelated or
> something.
> Will it?
3000 pixels at 1 metre work out to 3 pixel/mm, or ~76 dpi.
A 20/20 vision resolves reliably 1 arc minute (of black-white
contrast), or 3 pixel/mm from 1 metre distance.
For something to look pixelated, you need to be able to:
- see individual pixels as an area
- see a border where a change happens between individual
pixels.
Neither is given at 1 metre and 20/20 vision.
At 20-30cm you might see pixelation if the printer uses a nearest
neighbour interpolation (which I'd consider incompetent) and you
have hard contrasts between pixels; with smoother interpolations
(say, bicubic) you may notice some hard contrasts looking slightly
blurry, but shouldn't notice pixelation.
If you get much closer, the structure of the canvas will take over,
limiting resolution and giving the eye 'grip' even on otherwise
featureless areas, giving a stronger impression of sharpness
(you can also see that phenomenon with (artificial) film grain).
So, no, I'd not be overly concerned.
> If so, can I scale the image up and do something so that it
> doesn't print pixelated? Maybe blur it slightly to take out
> pixelation?
If you need to, ask the printer for the exact pixel size he'll use,
then upscale on your own and check on 100% view.
I'd assume the printer knew his tools and thus did the upscaling
and sharpening exactly as needed to get the best out of *his*
medium, while I'd not know.
-Wolfgang
[1] Printers may deliver very high dpi.
But even the most expensive ones only have a handful of colour
shades (e.g. black, photo-black, gray, light-gray, cyan,
light-cyan, magenta, light-magenta, yellow). So they have to
dither to get all the shades a photo has. Thus even 16x16
(==256) dpi may give just 1x1 ppi ...
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