DPI for magazines?

  • Thread starter Thread starter Just Allan
  • Start date Start date
J

Just Allan

Hi folks!

I want to scan some colour craft magazines for my wife and archive
them on CD-R. These will then be printed out as she needs them. Does
anyone know what resolution magazines are printed at - or maybe I
should say... the most appropriate resolution to scan them at?

Thanks for reading...

Allan.
 
If you are scanning whole pages the resulting files can be quite large and
slow to scan and print. You will probably decide to scan at the "lowest
acceptable resolution". the question is who gets to decide what's
acceptable? The answer is to experiment. Choose a typical page (with/without
photo?) then do some test scans and prints at various resolutions eg 75,
100, 200, 300 dpi. Write the dpi settings on the prints as it's easy to mix
them up if they are the same.Your wife will probably prefer 300dpi but you
may prefer 100 dpi or lower if you are doing the scanning :-).

Sometimes you get banding effects when scanning images from magazines. These
can sometimes be eliminated/improved by changing resolution (higher or
lower) or by applying a filter afterwards to slightly blur (soft focus) the
image. If you need a program to manipulate images it's hard to beat
Irfanview which is "free" from http://www.irfanview.com/

Hint: If possible configure your scanner S/W to create filenames that match
the page numbers in the magazine (Page001.jpg, Page002.jpg etc) or consider
using a renumbering program.

Colin
 
Thanks for your reply... I have a HP Scanjet 4100C - which is
defaulting to a scan of 150 DPI (but it seems to do that with
everything). I tried 600 DPI, but it seemed it was going to take
decades to scan each page. There's lots of sewing images in the
magazines with single thread details etc... Would 300 be ok you
think? I vaguely remember reading once that magazines are printed at
a fairly low resolution, but I can't remember what that figure was.

Allan.
 
Just Allan said:
Thanks for your reply... I have a HP Scanjet 4100C - which is
defaulting to a scan of 150 DPI (but it seems to do that with
everything). I tried 600 DPI, but it seemed it was going to take
decades to scan each page. There's lots of sewing images in the
magazines with single thread details etc... Would 300 be ok you
think? I vaguely remember reading once that magazines are printed at
a fairly low resolution, but I can't remember what that figure was.
Click to expand...

It's easy to confuse printing and scanning resolution. Photos for
print miught be scanned at 150 or 300 dpi. But the plates they're
printed from are made at, say, 1270 dpi. Partly that's because you
need to superimpose the patterns of the 4 ink colour separations. When
scanning colour if you hit some resonance with the dot pattern you get
banding. But solid colours, especially text, you want to scan at as
high a dpi as possible.

For small jobs you really want to to the images and text separately,
and OCR the text, and combine into a PDF. But this is hard to automate
and tedious to do by hand.

Whatever you do, it would be very convenient if you can put a whole
issue inot a single PDF file. (PDFs can store JPEGs as well as several
other formats in multi-page files.)
 
For small jobs you really want to to the images and text separately,
and OCR the text, and combine into a PDF. But this is hard to automate
and tedious to do by hand.

Whatever you do, it would be very convenient if you can put a whole
issue inot a single PDF file. (PDFs can store JPEGs as well as several
other formats in multi-page files.)
Click to expand...

Yep, good points - thanks!
 
Would 300 be ok you
think? I vaguely remember reading once that magazines are printed at
a fairly low resolution, but I can't remember what that figure was.
Click to expand...

I believe magazines are printed at 180lpi, not sure how that translates
into dpi.

300dpi is enough. However, the best would be to scan at 600dpi. Run a
descreen filter or blur/smart blur/minor Gaussian blur (to get ride of the
Morie patterns), then down sample back down to 300dpi. This method will
give you the best quality.

If the above method is too time consuming, then just scan at 300dpi and run
a descreen filter.
 
On Fri, 26 Mar 2004 15:57:23 GMT, CWatters wrote:

=>Sometimes you get banding effects when scanning images from magazines. These
=>can sometimes be eliminated/improved by changing resolution (higher or
=>lower) or by applying a filter afterwards to slightly blur (soft focus) the
=>image.

....or use a scanner such as the HP4270 which "descreens"
the image - eliminates those little dots that make up the
magazine or newspaper image. This does a better job than
the filters available in "free" image processing programs
bundled with Windows or scanners, but no matter which
method you use, you will get a more or less blurry image.

Secondly, keep in mind that because the magazine images are
halftones, a photocopier will usually always produce a
better image (albeit in b/w) than a scanner (you will have
to experiment with the light/dark control, though.) A
photocopier will always do a much better job on line
drawings. I'd use a scanner only if the colours were
essential -- and there is of course no guarantee that what
your scanner scans and your prints will have the same
colours as the source.

Finally, why bother? The printout will cost you upwards of
50cents a page/image, so the magazine itself is massively
cheaper....
 
I believe magazines are printed at 180lpi, not sure how that translates
into dpi.

300dpi is enough. However, the best would be to scan at 600dpi. Run a
descreen filter or blur/smart blur/minor Gaussian blur (to get ride of the
Morie patterns), then down sample back down to 300dpi. This method will
give you the best quality.

If the above method is too time consuming, then just scan at 300dpi and run
a descreen filter.
Click to expand...

That's the kind of expertise I was hoping for - thank you!
 
Finally, why bother? The printout will cost you upwards of
50cents a page/image, so the magazine itself is massively
cheaper....
Click to expand...

It's the only issue in an 80-volume set, that we can't buy anymore.
 
Lucas Tam said:
I believe magazines are printed at 180lpi, not sure how that translates
into dpi.

300dpi is enough. However, the best would be to scan at 600dpi. Run a
descreen filter or blur/smart blur/minor Gaussian blur (to get ride of the
Morie patterns), then down sample back down to 300dpi. This method will
give you the best quality.
Click to expand...

The above might be good for photos but not text or line art. There
really isn't a single setting that works for both. To do it right you
really need to treat these separately.
 
(e-mail address removed) (Alan) wrote in
The above might be good for photos but not text or line art. There
really isn't a single setting that works for both. To do it right you
really need to treat these separately.
Click to expand...

Ah true - the descreen and downsample is used only to remove morie
patterns. I assumed the magazines he'll be scanning contained a mixture
of text + pictures.

It won't hurt to use the above method on pure text, just that it'll be a
waste of time.

Typically for text, I scan at 300dpi (or even 600dpi), black and white.

I find greyscale occasionally picks up the white paper as grey and it
takes too much effort to tweak each page.
 
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