This will be a one-morning workshop for people with (I suspect) few computer skills, so I've tentatively ruled out Gimp - although it is certainly very powerful, I am worried my beginners would spend the whole time struggling with the interface (and asking me nightmarish questions about obscure options that I've never actually used... :-D )

Pixlr seems to use mostly 'proper' image editor terminology in common with Photoshop and Gimp, which seems like a better option than the tools that just present a bunch of buttons to apply custom filters, so would be good from that view point.

My tentative list of content goes something like:


Filesize basics, compression and formats
Composition & cropping
Using unsharp mask, saturation & histogram adjustment to improve light, colour and sharpness.
How and when to use black and white, sepia, and other effects

That seems like more than enough for a morning with a coffee break!