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Installment
1: Image Size
When
dealing with what can effectively be called "pictures",
or basically anything that is not made up of text, the "size"
of that imagery can be looked at in three different ways:
- The
dimensions of the image on the computer screen.
- For
example: 400 pixels wide by 300 pixels high. As many
of you may know, every image on computer screens is
measured in pixels. Every computer screen is set at
a particular screen resolution, be it 800 x 600 pixels,
1024 x 768, or larger. Therefore, if a computer screen's
resolution is set at 800 pixels wide by 600 pixels high,
a 400 x 300 pixel image will take up half the width
of the screen. By the same token, when projected in
a presentation, that image will take up half the screen
it is projected on, because projectors project what
is on the computer screen.
- The
dimensions of the image when printed.
- However,
that same 800 x 600 pixel image might only be 1 inch
wide by 1/2 inch high when printed, because measurements
in pixels are designed for the "electronic environment"
only. The web, onscreen presentations, video, multimedia,
etc. Outside of the "EV", everything is measured
in inches. So if it looks "big" onscreen,
that doesn't mean that size is going to transfer to
print the same way. For instance, have you ever downloaded
a picture from the web, printed it, and it was tiny?
Thats why. Just because it's big and visible onscreen
doesn't mean it will be the same on paper.
- The
actual file size of the image, or "how much memory
it takes up"
- Now
it gets really complicated....we've talked about "size"
from the standpoint of print (inches) and the standpoint
of the EV (pixels). Now we are going to talk about
size from a standpoint that actually has nothing to
do with measurements at all.
Have
you ever recieved a file via email that took forever
to download? Or one that completely locked up your email?
It was probably a file that carried LOTS of memory with
it. namely, a 5,6,7,20,30, megabyte file.
One
Media Center staffer has experienced a career high
Powerpoint presentation file size of 80MB. It was
later optimized to 1.5MB with no image quality loss.
A
rule of thumb (for the electronic environment - web,
PPT, multimedia - especially):
MB
= Not Good. (Note:
Video is different. Video files tend to be big. The
"nature of the beast"...but that is a whole
different ballgame)
One
of the first things we at the Media Center do when
beginning a project (and especially one that is going
to be used in an electronic environment) is we check
the file sizes of all the imagery we are putting into
it. File sizes that are approaching 1MB are immediately
flagged for optimization* Not a good thing to rush
to finish a job, and then realize past deadline that
it can't be emailed or used on the web because it
is too big.
("Like that great picture that was used in
"that" Powerpoint presentation...turns out
it was 4000 pixels wide by 2500 pixels high, and 5
feet wide by 4 feet high. Made a great poster...Oh,
wait, there were five of them in that presentation...no
wonder it was 20MB")
*Optimization:
An
electronic process that takes High-Resolution imagery and
essentially "trims the fat" from the imagery, thereby
lowering the resolution of the imagery without compromising
image size or quality. While the process has limits, it can
be used very effectively.
The bottom
line here is that the more high-resolution imagery you add
to a file, the bigger the file is going to be from a memory
use standpoint, and on the web, it just won't work.
However,
we are not saying lots of imagery should not be used in presentations
and on the web - the more the better, but what we are saying
is that imagery should be checked for file size first,
or better yet, contact the Media Center and we can handle
that for you.
Or answer
any other technical questions you may have. Thats why we're
here.
NOTE:
All of the imagery seen on this website was originally high-resolution
imagery, however, the entire memory use of this entire site
is less than 1500k
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