I just read this in a family newsletter and
thought I'd pass it on. I'm now going to have to rescan all my originals! :-(
Now, lets turn to the differences between the
file formats TIFF (Tagged Image File Format) and
JPEG (Joint Photographic Experts Group). When
I teach scanning, I am always surprised that some
people are still scanning and saving their
familys prized photographs as JPEGs. If the purpose of
scanning your family photos is to preserve them, never save them as JPEGs!
A JPEG is a lossy compressed file. This means
that every time you save your image, part of that
image is lost. In the beginning, you probably
wont be able to detect the lost parts of the
file, but eventually you will notice
deterioration of the scanned photograph. These losses are often referred
to as JPEG artifacts. Jaggies or jagged edges
in your photo can be another sign of image
degradation. Recently, I had to re-scan some of my own
photographs done before I knew better because
of losses in the digital images. Dont get me
wrong there are uses for JPEGs. They are great for
populating websites or sending through e-mail,
but they never should be used for archiving,
retouching or restoring. All of that work should be done
on a TIFF image. Later, you can convert it to a
JPEG if needed. Also, always work, retouch, and
restore on a copy of the photo. Keep the original
photographic image stored safely away.
Lets also dispel a JPEG myth. You can open a
JPEG any number of times and nothing will happen
to it. The only time anything happens to a
JPEG is when you Save it. Saving automatically
activates the compression programming of a JPEG,
and that is when pixels are eliminated. If you
put a JPEG on a CD, DVD or flash drive and never
touch that image, you will not lose any of it.
However, if you are scanning an image and save it as
a JPEG, you have lost part of it already. So, if
you are scanning family photographs for
preservation purposes, start by using the correct file extension
when saving your scans. The best file extension at this time is still a TIFF.
It is important to mention that most digital
cameras save their images as JPEGs. So, if you
have an image shot with a digital camera and you want
to save it without eventual JPEG artifacts
showing up, I suggest changing it to a TIFF for
archiving purposes. TIFFs will use a lot of memory, but get
into the habit of taking those images off your
computer hard drive and putting them on another
storage device, such as a CD or flash drive and keep
backups. Eventually, there will be other ways to
save and archive photos, but for now a TIFF is
the only recommended way to do so.