> I received a couple of QR codes from my friend in Japan (from
> my address book entry in her phone, a couple of emails, etc) and the size
of the
> PNG file she sent me was roughly 120 pixels by 120 pixels - is that a
> common size?
I dunno if there is such a thing - the DoCoMo QR code creator offers various
sizes, and creators can adjust the size non-destructively in a graphics tool
for magazine page or poster presentations.
> What kind of camera resolution is usually good
> for reading that back?
Depends on the optics (i.e. to present a large code area onto the image
sensor; more is better of course) - I think this was covered before with the
'macro' discussion. I'd say roughly (in theory) the sensor's pixel count
ought to be at least double the dots effectively being imaged (under ideal
conditions - large code image presented, no hand movement, good focus etc).
Of course that doesn't happen so you've got 600k or mega-pixel sensors..
> Is it also correct that the printing is typically
> expected on a 400dpi printer?
It needn't be. Due to the blocky nature of the code, you could get away with
less (say 150dpi) if it were the only thing you are printing - test before
releasing - that's a must. Usually 300dpi or higher is done since the code
is part of a regular page layout. BTW if you're including it in a mag page
(or other 'busy' surrounding content), it's very important to have a
sufficient white space surrounding the code.
Regards
Michael.
Received on Tue Jul 12 10:01:17 2005