| Walter Donavan 2003-11-27, 6:13 pm |
| I'm a little rusty on this but I will take a stab at it.
Pixels per inch is one measure of resolution. Anything above 96 dpi on a PC
is wasted; PC monitors can only display 96 ppi or less. (Macs can only
display 72 ppi, which you hear that number.)
There is therefore no point in increasing ppi beyond your monitor's maximum.
Ppi is only for your screen. Windows (or Linux or whatever) controls that.
Printing is a whole 'nother matter. There the measurement is dots per inch
(dpi), which term goes back to the days of half-screen printing. X dpi = x
half screen dots per inch. 120 dpi screens, 80 dpi screens, etc., were
actual physical wire screens with mesh densities like those listed. Larger
numbers were used for glossy coffee table publications, etc.
Printing is normally done at 300 dpi, even for publication. However, it can
be done acceptably at less (uses less time and less ink), while glossy
magazines and printing photos on your inkjet use resolutions considerably
higher, which is why you will see numbers like 1600 dpi, 3200 dpi, etc.
You can set the dpi resolution of your image in an image editor such as
Photoshop. I don't know how Image Composer (IC) handles that; It is only
intended to create web graphics and therefore uses only 96 dpi. But I'm not
positive how it prints.
PhotoDraw (PD), the companion program to IC, offers three resolutions for
printing but doesn't tell you what they are. Use Tools > Options > Picture
Quality and you will see "Web," "Typical (Photographic)," and Professional
(best for printing)."
I think those labels are misleading, because Professional only goes up to
300 dpi, I believe. Web is 96 dpi and Typical is something like 180 dpi. You
can create images with the three resolutions and check the actual dpi
numbers in Photoshop, Paint Shop Pro or similar. I have done that but I
forget the exact numbers.
Anyway, to answer your question: If you increase dpi, you will increase
print resolution only, and may or may not increase image size.
There is more to it than that. PD is notorious for not doing what other
image editors do. Photoshop will adjust image size to match the new
resolution. I believe it will also adjust resolution to match image size. It
can get tricky. It is possible to force Photoshop to increase dpi without
increasing image size, but it takes a bit of work. I assume that is what you
want to do: print a higher quality image. Yes, you can do that, but at the
expense of a bigger file.
You also can't add sharpness that isn't there (usually--there are
professional tools that can do that to some degree). So increasing dpi is
usually just to keep your printer people happy, not to achieve a higher
quality image.
If you have the resolution to begin with, such as with a 5 MPixel digital
camera, of course you can print big, high-resolution prints.
--
Walter Donavan
Author of "Revelation: The Seven Stages
of the Journey Back to God"
www.revelation7stages.com
www.1stbooks/bookview/15479
"Joe Scholnick" <anonymous@discussions.microsoft.com> wrote in message
news:07e001c3a3f9$127bbff0$a101280a@phx.gbl...quote:
> I'm confused by the relationships between pixels and image
> size and resolution. Can anyone explain to me the
> relationships? Can in increase pixels per inch without
> changing the size of an image, and the resolution?
> joeskole@aol.com
|