Scaling vs. Resampling for Printing

[One4All]

Maybe I know the answer to this question, but I'll toss it out here,
anyway. I want to make a print of a PS photo on 11x14 paper. I want
the resolution for my print to be 360 ppi/dpi. I have an Epson 1280,
so with 720 ppi/dpi max, I can use 360 (720/2) or 240 (720/3). But,
this isn't the issue. If you want to make it one & say, "Use 300 ppi/
dpi and forget about it," well, ok. Whatever.

The issue is, whatever the resolution, that's what I want for my
print. So, in Image Size in PS (I have PS ver. 8, btw), I set the
resolution to, say, 360 ppi/dpi, but the image size without resampling
is larger than 11x14 paper will accommodate. I do not want to resample
the photo, because resampling degrades the image, even though I'm
working with a duplicate of the main file.

So, in Print With Preview, I scale the photo to a size that will fit
on 11x14 paper, instead of resampling in Image Size. The resulting
print is acceptable. Does anyone care to comment on this? It seems to
me this workflow is far better than messing around with resampling. Of
course, the resampling issue could arise if I wanted to, say, print at
16x20 or larger @ 360 ppi/dpi. But, with scaling, couldn't I go to a
larger size? Couldn't I do this without resampling?

I guess what I'm asking is, at what point will scaling let you down?
At what point do you have to resample? I'm working with a 78.4 MB
file, btw, but I think specific file size doesn't matter.

 

[Arthur Entlich]

If I understand you comments correctly, you took an image that was
larger than the image print size if set to 360 ppi, so you had the
resolution be brought up until the image was the correct size, which
might have, for example ended up 404.8 ppi.

If what you are asking is how this affects print quality, the answer is
very little.

Most desktop Epson printers resample before printing to 720 dpi
regardless of the resolution you feed the spooler with. You can pretty
much ignore the old 240/360 ppi epson issue. The new drivers are so well
behaved, it makes no visible difference if you use the exact divisor or
not, because of the nature of the spooler image raster technology. The
spooler actually creates the image from a new starting point with every
few pixels, so those exact magic number make little to no difference.

The best basic formula is not to throw away resolution, so there is no
value to resample downward. Just use the native maximum resolution.
When upsampling, it is a bit more tricky, because Photoshop, for
instance has some very sophisticated algorithms which may be superior to
Epson's when major resolution changes are made. Even they can't agree
though if it is best to upsample in steps or all at once. Current
wisdom seems to suggest doing it in steps when making large changes.

But keep in mind that the Epson drivers, if you use them, will produce a
720 ppi raster before printing, so unless you are going to make your
file 720 ppi, the final say is Epson's.


Art