[scribus] Placing /Scaling and file image/PDF size

jwminer at accessvt.com jwminer at accessvt.com
Fri Oct 31 17:43:55 CET 2008

Mike wrote:
>> I am still hoping for a suggestion to finding out pixel sizes of
frames *prior* to placing the image.
If I know this then I can resize very closely to the exact sizes needed
and thus cut down on the image file sizes. >>

Pixel sizes do not tell us anything about the size in inches
(centimeters, picas, whatever) of an image. There is no such thing
as a pixel size of an image frame. Your images contain a certain
number of pixels. The *resolution* depends on what size you choose
for the image--that is, if an image has 1200 pixels across and you
put it in a 3-inch frame, the resolution is 400 pixels per inch; if
you put it in a 4-inch frame, the resolution is 300 pixels per inch;
if you put it in a 6-inch frame, the resolution is 200 ppi.

If you are printing, you want about 300 ppi (or dots per inch) for
your images. If you are designing the document solely for onscreen
viewing, about 100 ppi will be fine. Anything larger just makes the
file larger than it needs to be and it will not make for a
better-looking image.

If your frames are roughly the same size, say, medium-sized
(whatever that may be), take the largest dimension and multiply it
by the size suitable for your output. So say the largest dimension
of the medium-sized frames if 5 inches and you're going to print the
document. Multiply 5 times 300 and you get a longest PIXEL size of
1500. So you resize your images so the longest side contains 1500
pixels.  If some medium-sized frames are somewhat smaller than five
inches, you can still use the 1500 pixel image. If you have some
frames that are a lot larger (say, full-page) or smaller (say, 3
inches or less on the longest side), multiply the size in inches of
the longest size by 300 (for print). Then resize your large and
small images so that the pixels for the longest size are, say 900
pixels for 3-inch or smaller frames and 3000 or 3300 for 8x10 or
8-1/2x11 pages to be printed.

To summarize, a frame has NO PIXEL SIZE. To resize images to the
correct size for a frame, multiply the longest side of the frame by
the ppi/dpi suitable for your output device (screen, printer). Make
sure you tell the program that is resizing the images that you want
resizing to be proportional. If the image itself doesn't have enough
pixels on the longest side to provide the dpi/ppi needed for quality
output, you're in trouble. Upsampling the size of a raster image
results in loss of quality.
--Judy Miner

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