The basics

258 ADVANCED PHOTOSHOP ELEMENTS 5.0 FOR DIGITAL PHOTOGRAPHERS
EXTENDING YOUR WEB
ABILITIES
1. JPEG, or JPG, or Joint Photographic Experts Group, is a fi le format specially developed for
photographic web images. It uses a lossy compression technique to reduce fi les to as little as 5% of
their original size. In the process some of the detail from the original picture is lost and ‘tell-tale’
artifacts, or visual errors, are introduced into the picture. The degree of compression and the amount
of artifacts can be varied so that a balance of fi le size and image quality can be achieved. More
compression means smaller fi le sizes, which in turn means poorer image quality. On the other hand
less compression gives larger fi les of better quality JPEG images that can contain millions of colors
rather than the comparative few available when using GIF. The format has massive support on the
net and is the main way that photographers display their web pictures.
2. GIF, or the Graphics Interchange Format, has
had a long (in internet terms) history with web
use. It has the ability to compress images mainly
by reducing the numbers of colors they contain.
For this reason it is great for headings, logos and
any other artwork with limited colors and tonal
graduation. It can also display pictures that
contain areas of transparency and can be used
for simple ‘cell-’ based animation. This format is
not suitable for most photographic images.
How big is too big?
When you are producing your fi rst web pages
there is always the temptation to keep as much
image quality in your pictures as possible,
resulting in large fi le sizes and a long wait for
your site visitors. Use the table aside to help
you predict how long a web picture will take to
download to your recipient’s computer.
Step 1 >> Open the original image
and select the File >Save for Web
feature. Input the image size into the
New Size section, being sure to keep
the pixel dimensions less than 640 x
480. Click Apply. Set previews to 100%.
Book resources at: www.adv-elements.com
Balancing Compression and Image Quality >>
Photographers wanting to display their images on the net are caught
between the two opposing forces of image quality and image fi le size.
When Adobe created Elements they were well aware of these diffi culties
and, to this end, they have included sophisticated compression features
that give the user a range of controls over the process.
The Save for Web feature contains a Preview option that allows you to view
the original image after the compression and conversion to web format has
taken place. In addition, the dialog also displays predicted compressed
image sizes that will allow you to ensure that your web fi les are not too
cumbersome and slow to download.
File size Download Speed
14.4 Kbps
(modem)
28.8 Kbps
(modem)
56.6 Kbps
(modem)
128 Kbps
(Cable)
30KB 24 secs 12 secs 6 secs 3 secs
100KB 76 secs 38 secs 19 secs 9 secs
300KB 216 secs 108 secs 54 secs 27 secs
1000KB
(1MB)
Step 2 >> Try different fi le format,
compression setting or numbers of
colors. Determine the best balance of
fi le size and image quality. Check the
download times. Click Save to store
the image.
720 secs 360 secs 180 secs 90 secs
Step 3 >> After creating the gallery
images you can repeat the process
using smaller pixel dimensions to
generate the thumbnail versions of
the pictures. Thumbnails should be
between 60 x 60 or 100 x 100 pixels.