Filmscanners mailing list archive (email@example.com)
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
filmscanners: Re: File sizes, file formats, etc. for printing 8.5 x 11and 13 x17...
At 8:44 AM -0600 2/27/01, Marvin Demuth wrote:
>As I prepare for scanning for these size prints, it will help me, and I
>suspect others, if some of you scanning for quality 8.5 x 11 and 13 x 17
>prints from 35mm in either b & w or color will comment on:
>1. The typical file sizes you use at the printing stage and the ppi of your
>2. The file format of the file at the printing stage.
>3. How you archive your final scans used for the printing, i.e. CDs, etc.
>4. The bpi and ppi confusion.
You will probably get a number of different opinions on this,
and they may all be good.
1. In my case, I always scan at the optical resolution of the
scanner (2720 ppi with my Canon FS 2710). This gives a file of about
26.5 Mb (assuming you are using an 8-bit file).
For printing I resize to the size I want in Photoshop's Image
Size ("Resample Image" unclicked) and let the resolution fall where
it may. There have been many discussions on the "ideal" image file
resolution for Epson printers, but the consensus seems to be
somewhere between 240 ppi and 360 ppi. My tests showed that there was
some improvement in going up from 240 to 300 to 360, but that there
was no degradation of the print using odd resolutions such as 347 ppi
or 353.753 ppi. Some people have claimed that using odd values for
resolution affects the quality of their prints, but I haven't found
that to be the case.
As it happens, 360 ppi gives you about 10.3 x 7, which is the
maximum printable length on the Letter setting, and 240 ppi gives
about 10.5 x 15.5, a handy size for A3 or 11x17 paper.
2. I usually use .psd files for printing, but .tifs do as well.
3. I archive on CD-Rs. The consensus here seems to be to use
gold-dye CD-Rs for maximum file stability. Good formats again include
.psd or .tif, but TIFFSs can be read by more image programs than
4. I'm not sure what you mean. Do you mean dpi? If so, dpi is
a convention used by printers, but it is less meaningful with
printers such as Epsons, which use a random dithering pattern to lay
down ink drops. The common values of 720x720dpi or 1440 x720 dpi used
by Epson don't mean much, except that 1440 usually gives a smoother
output with less horizontal banding. It refers to a smaller
incremental movement of the paper as it goes through the printer, not
that the printer is putting out more dots of ink per inch.
Ppi is strictly a digital notation that describes the number
of pixels making up an image. For example, a raw scan from a Canon
FS2710 is 2720 ppi, but if you printed the image, it would only be
about 1x1.5 inches, the size of a 35mm frame. That makes the number
of pixels about 2600 by 3700, or about 26.5 Mb (depending on how
close to the edge it is cropped). Thsi information shows up in the
Image Size box. As noted above, this image can be resized at will -
lowering the resolution automatically increases the size it will
print. This makes no difference to how it looks on your monitor -
Photoshop for example always shows a % number at the top of the
screen. This relates to how image pixels relate to screen pixels.
This gets complicated by what resolution your monitor screen is set
to, so I'll leave it at that. For the most accurate view of your
image, use100%, as this gives one screen pixel for each image pixel.
You will find your images look better at the even divisions of 100%
(12.5%, 25%, 50%) than at the odd numbers like 33.3% and 66.7%.
I hope this isn't too confusing. I see other answers are
starting to appear, so I'll leave it here.