> My main point is that if you shoot for reproduction, you do
> indeed need 300, as that is the standard for press work.
VERY true. However, you may not need native camera resolution
to get there. Scaling engines will get you there too. When going
to press, you need 300, but the actual printed resolution is
less than half that. I've sure seen some outstanding
double-truck images that have come from 6MP (and less) cameras.
According to the math, a double-truck with bleed needs far more
than 6MP. I'm not saying that extra pixels doesn't hurt,
though.
When it comes to non-press, the scaling method makes a lot of
difference in how the final print is going to look. Printers
have a "native resolution" which is generally technology
(hardware) limited. It only makes sense to work with the grid
system and the pitch of that grid varies from brand/model to
brand/model. But this is all internal to the printer. Which
leads to the next point:
Many printers have a 300 ppi pitch. If you feed an image to it
that comes in at say 284 ppi, it will "scale" the image on the
fly. Depending on the quality of the scaling engine, it may or
may not visibly degrade the printed image quality. I use a
professional lab that has a scaling engine in the RIP which is
far superior to anything I have in my own computer. I just send
them the standard file and let them scale it to whatever print
size I ask. Another professional lab I use uses a different
type of RIP and printer and I have to do the scaling myself if I
want anything decent from them.
We have this mental image of how "things used to be" with
blowing up 2MP images up to 13x19. In those days, the best
scaling mechanism we had was BICUBIC. The pixelization and
artifacts really were nasty. Not true today. Even BICUBIC has
improved, and we don't have to scale nearly as much with the
higher pixel counts. I can guarantee you that a WELL DONE print
from a HIGH QUALITY 200 ppi image that has been scaled to 300ppi
vs natively printed at 300ppi is essentially indistuinshible
from each other. Why?
A 300 ppi printer is almost always unable to keep the dots
within the pixel bucket. There is a certain amount of bleed that
occurs with the nearest neighbors. Inks/dyes/pigments spread
(dot spread), paper fibers transport inks laterally, and even
the take up emulsion of the coated papers will move the inks
sideways. In traditional film/paper/optical enlargement, you'd
get a certain amount of lateral halation in the emulsion. By
allowing the dots to blend together, a printer is pretty much
unable to provide 300 ppi "resolution", only 300 ppi
"placement".
As proof of this, create a new image in your editor of choice
and create a fill pattern of alternating lines only one pixel
white and one pixel black. Now print this at the native pixel
pitch. (300 dpi). Can you see the lines in the print? Now
start "enlarging" this image until you can see the lines. This
will give you an idea of what the "native resolution" of the
entire imaging chain is.
AG
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