Worth a read ACM article "Photoshop Scalability: Keeping It Simple"
This article is worth a read if you are interested in parallel programming: "ACM Queue; Photoshop Scalability: Keeping It Simple."It is an interview in ACM discussing parallelism in Adobe Photoshop. I found it very interesting - covering the earliest uses of parallelism for what I call "convenience" instead of "performance" and how that evolved when parallel programming could yield performance boosts. The interview also talks about the methods of decomposing algorithms that have worked best for Photoshop.
Intel Threading Building Blocks (TBB) is mentioned although only briefly. Adobe did incorporate TBB in early 2010 into several of its Creative Suite 5 software applications including Photoshop.

