On Wed, 2012-04-25 at 16:25 -0500, Daniel Smith wrote:
> So, the 144 would be basically twice the web resolutio of 72 to make
> for better resampling on resize, or no relation?

Well, if by Web you mean World Wide Web, no, no relation; there are 72
points to the inch in printing, and a lot of printing setups in practice
are optimised to work best with multiples of 72dpi when making a
half-tone screen for each colour - the ink is either on or not-on at
each location ad the RIP in the printer (or a separate box in your case,
probably) turns each pixel in the image into a rough circle of lots of
device dots, fewer dots for less colour.

Slightly longer answer -
The hardware device might be 1440 device dots per inch, but at 144dpi
that gives a 10x10 square of little dots for each pixel, so only 100
colour levels are possible. That's likely to be enough for printing on
fabric, though.  At 72 or 75 lines per inch (ppi, or dpi from the image
perspective) on a 1440dpi printer you get 19 or 20 dots on a side, so
around 400 levels, and although that's more than 8-bit colour can
represent, it gives the RIP more felxibility in the shape of the clumps
of dots.


Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/

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