Photoshop: a few online resources
PDFs:
How to create Masks and Use Channels.
How to optimize files, from our in-class tutorial.
Creating transparent gifs and matte effects.
Adjusting images and a jpg mask.
Links:
GrafX Design
This site includes some slightly outdated, but still useful, tutorials on using Photoshop to create Web graphics. Rembember that you have ImageReady at your command as well when you're reading these!
Finally, you can also get a list of other resources that are available from Adobe at their Photoshop training page.
