[Air-L] Readings in semiotics/multimodality: Alternatives to Kress&Leeuwen?

Hi This is the second time I use Gunther Kress and Theo van Leeuwen's "Multimodal Discourse" (http://www.amazon.com/Multimodal-Discourse-Gunther-Kress/dp/0340608773) in my web design and web aesthetics class (introductory level). The students (non-natives, but quite capable users of English) keep complaining about convoluted language and dense ways of explaining. Are there alternatives to this book which cover about the same topics, and have the same depth, but are easier accessible? Or are there any additional texts which help understanding once Kress is mandatory reading? Thanks, - Daniel