Graphics Programs Reference
In-Depth Information
Preparing any content for
web use is concerned with
balancing quality and file
size. This is especially true
when placing your pictures
on the Internet. Too high
quality will mean that your
photos will take a long time
to display, too little and they
will download quickly but be
of poor quality.
Most of the web features in Photoshop Elements automatically handle the process of opti-
mizing your photos so they are suitable for viewing on the Net, but there will be times when
you may need to save an image in a web-ready format yourself. So let's look at the process
that you can use to optimize photos manually.
Both JPEG formats, as well as GIF and PNG8, make small files by using 'lossy' compression
algorithms. This means that image quality and information are lost as part of the compres-
sion process. In simple terms, you are degrading the picture to produce a smaller file. Too
much JPEG compression, in particular, and the errors or 'artifacts' that result from the qual-
ity loss become obvious.
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The compression technology built into the GIF format makes files smaller by reducing the number of colors in
your pictures to a maximum of 256 (8-bit color). This means that GIF images are small and fast to display but
the lack of colors makes them unsuitable for use with photographs. (1) Original 3.53 Mb picture containing
16.7 million colors. (2) Detail of original. (3) Detail of the same file converted to GIF format so that it is
0.43 Mb in size and contains 32 colors only.
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