Create graphics that load fast, and a
still look good. Keep file size as small as possible without sacrificing
image quality.
All graphics should be in standard web native
GIF, JPEG, or PNG formats. Make sure they are RGB or index color.
Tiffs, jpegs, and EPS images that are used for print are usually in
CMYK format - these will not work on the web. These must be
converted to RGB or index color to be viewable on the web.
All graphics should be at a resolution of 72 pixels
per inch (ppi). Graphics used for print and other applications
may be at resolutions of 150 to 300 ppi. Make sure to convert them
down to 72 ppi for use on the web.
All graphics should be sized to the the width
and height that they will appear on the page. Do not shrink images
on your page. This wastes bandwidth and re sampling is often
poor. It's better to resize images in a graphics program prior to inserting
them into your document.
If you're hand coding, use HEIGHT and WIDTH attributes
with images to speed page loading and to aid assistive technologies.
Use the ALT attribute. If the graphic doesn't
convey information, use ALT with empty quotes "".
Where color is key to understanding the graphic,
use value contrast, supporting text or other alternative.
Optimize PDF files for download display (recent
versions of Distiller offer an eBook set of job options which is
convenient for those who don't want to tinker with settings).
