In addition to photographing Special Collections materials for ongoing digital projects, or for patron requests for publication, Digital Production Services also digitizes items to be featured in library-produced promotional publications. In 2008, a coffee pot once owned by “Dr. Bob” (Rober Holbrook Smith), a founder of Alcoholics Anonymous, was taken off the shelf and set against a simple white background to be photographed.

The photograph itself is a straightforward shot — at the time, captured using the John Hay Library’s Nikon Digital SLR camera. However, to remove the background for a publication layout, “clipping paths” were created in Adobe Photoshop. Clipping paths are a useful way to mask-out the background within a scene — in other words, clipping paths can be used to visually define the edge of an irregularly-shaped object which does not conform to a standard rectangle-based crop.

Above, L–R: detail of coffee pot digital image; detail of image with background removed via pixel-based selection; detail of image showing vector-based clipping path overlaying pixel grid; clipping-path-masked image as placed in final layout.

There are pixel-based methods of creating masks in Photoshop, although clipping paths offer a unique solution, storing resolution-independent Bézier-curved (vector-based) edges alongside the pixel-based image grid, particularly useful for layered layout designs. Curves used for clipping paths are the same vector-based curves now becoming more widely supported by web browsers, as part of the Scalable Vector Graphics (SVG) specification and HTML5’s <canvas> tag scripting. (For an example of resolution-independent, vector-based curves implemented solely via web-based technologies, see this proof-of-concept site by a Google employee.)