is a little-understood concept in digital image manipulation. The details
of issues of resolution, print size, and display size, are explained
below. Although your software will largely manage these issues for you,
you can avoid unpleasant results if you understand the concepts.
Relative size: Be careful of the appearance of
size - it is relative! First of all, most software allows you to zoom -
make sure you're viewing your picture full-size (1:1) before you decide to
change it. Above, Paint Shop Pro is displaying at 1/2 size (1:2), which
means the picture would actually be twice as large if displayed on a web
Somewhere in your software's display (at the lower
right hand corner in Paint Shop Pro) is the exact dimensions of your picture in pixels. A pixel is
one "piece" of color - greatly enlarged, it will be a square of
one solid color. The physical size of your picture when printed is a combination of pixels vs.
resolution (measured in pixels per inch) - a
picture 576 pixels wide at 72 pixels per inch will be 8 inches
wide. However, the same picture can be printed at 4 inches wide, and the
resolution is now 144 pixels per inch - an apparently sharper, higher-quality image. Likewise, the same picture could be printed poster-size at
32 inches wide - but the resolution would be 18 pixels per inch.
Normal view vs. 6X enlargement showing
What does this mean? It means, enlarging and
shrinking your picture doesn't increase the number of pixels,
it only makes them more or less large, and hence more or less visible to
the naked eye. A "pixilated" image - one at low
resolution (see at right) will look fuzzy and
splotchy, as the pixels get larger.
This is the most visible with print. On your computer
screen, enlarging and shrinking is less problematic, since the your
computer display has fewer available resolution settings, and
pictures are usually being shrunk rather than enlarged.
Since pixels is the unit of measure of screen display on a computer, the size of a
picture on a computer (without intervention from you or software) is
dictated by pixel dimensions only. But be mindful - if someone else has the
same screen size as you do, but has the pixel resolution set to 1280X1024,
the same picture will look a lot smaller on her machine!
Sizing in Your Software:
Since Word, Publisher, PowerPoint, all give you control over image size,
it is not necessary to use your graphics program's resizing options with your
picture. The Web is another story - there, since your picture must be
squeezed through a relatively small wire, it's important for its file size to
be as small as possible. FrontPage will "Resample" pictures for
you, which works well, but resizing in your graphics program gives you more
control. Remember to save in a reduced size only as the last step, since reducing
size actually changes the resolution (reducing the number of pixels), so your
picture's quality will be reduced. Controlling color
count also helps.