LuAnn,
Russ is exacty right. It's the old GIGO theory/ (garbage in, garbage out).
Things always look better on your monitor, don't they?
Where I work, we always have to check to make sure that hi res images are
300 ppi. A lot of folks confuse dpi with ppi.
If i ever need to enlarge a scan, I take that into consideration when
scanning. If I want to enlarge a 3" x 5" to 6 x 10, I always double the
scan resolution to 600 dpi. My scanner won't let me dictate ppi.
If I want to enlarge a scan 4 times original size, I scan at 1200 dpi. We
output everything at 2400 dpi/ 175 lpi. That's when input vs. output
reolution comes into play.
Good luck, and watch those input resolutions.
Ray White
Neff Packaging Solutions
1700 Watterson Trail
Louisville, KY 40299
Tel: 502-491-1820 ext.330
Fax: 502-491-7701
www.neffpackaging.com
"R. D. Preston"
<preston.r.d at earthlink.net> To:
macgroup at erdos.math.louisville.edu
Sent by: cc:
owner-macgroup at erdos.math.lou Subject: Re:
MacGroup: iPhoto sharpness
isville.edu
01/05/2006 01:51 AM
Please respond to macgroup
On Jan 4, 2006, at 10:10 PM, LuAnn Johnson wrote:
>
> I edited some pictures with iPhoto, and sharpenening them just a
> little made them look clearer on the monitor. I then put 8-10 on
> one 8.5x11 page in Appleworks drawing and printed them at Wal-mart
> for a friend to use in scrapbooking. The results are horrible -
> everything is splotchy and grainy - the way it looks when I over-
> sharpen.
>
> I printed them again on my home HP printer, and they are just as bad.
>
> The pictures look perfect on my monitor, so I don't know why this
> is happening. Could it be because I shouldn't have adjusted the
> sharpening?
>
> When I've done slideshows on iMovie, I have always sharpened the
> photos just a bit, and they look much better. The pictures that
> look great in iMovie look horrible when printed.
>
> Any advice or suggestions?
>
> Thanks.
>
> Luann
>
Hello Luann,
Well, it's been a very long time since I've discussed this, but I'll
attempt it
(albeit setting myself back a at least a decade) because my photo-
application
of choice is Photoshop 3 ? now years old. However, the basics
should still
be the same. As I see your described problem, it's just the
understanding of
a key piece of the photographic/print process that you need.
<: Resolution :>
If you can, check the resolution of your photograph. If you are
starting with
a traditional photo, it is probably a continuous tone, and I'll
assume you've
scanned it in. Check the scanning software settings for resolution
reference.
Traditional photographs are continuous tone from lighter to darker
shades,
have used some sort of screen in the bulk printing process to break
up the
image so the printing presses and printers can print a facsimile of
the
photograph. Modern digital cameras refer to pixels, megapixels,
etc., which
is roughly similar to resolution, but much finer.
Many photographs found on/for computers have a 72 dpi resolution, by
default. High quality photos may (should) have a much higher res.
References:
-- "D.P.I." (dots per inch)
-- "L.P.I." (lines per inch)
-- "P.P.I." (pixels per inch)
Monitors have two kinds of resolution. There are differences, but
commonly,
monitors have a (device) pixel density of 72 ppi. This is
different from the
choices offered under the 'Displays' prefs (software), which only
changes
what you see on screen, not the device pixels themselves.
Printers print at certain resolutions, and may offer several
different choices
of available screens in different *patterns*, and possibly dpi/lpi
density to
choose from when applying to a photo to print. When you see a printer
resolution reference of 300 dpi, 600 dpi, 1200 dpi, etc., that's
the general
resolution for print output.
For decent quality output for any unaltered photo, you should have a
minimum
of 300 dpi; 150 dpi is course, but can work. If you are altering a
photo and plan
to publish by printing, your picture should probably have a minimum
600 dpi
resolution.
Internally, your photo may be a 72 dpi (course resolution), and when
sharpened,
it will have essentially made the pixels *more* course from pixel
to pixel. When
you view these pics on similar monitors/devices, they look fine.
Printing, however,
will amplify these differences, not improve them. If you are going
to publish to
CD or Web, monitors will display your images fine, but if you are
going to publish
by printing, *start* with a relatively high resolution picture (300
to 600 dpi).
If I haven't been too terribly wordy, I hope this helps.
Regards,
Russ Preston
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