The majority of commercially available image processing and data visualization systems employ a dataflow paradigm. Users select modules from a menu and wire them together using an interactive flow chart editor.

I will describe an alternative paradigm based on spreadsheets. Cells in such a spreadsheet contain graphical objects such as images, volumes, or movies. Cells may also contain graphical widgets such as buttons, sliders, or movie viewers. Objects are displayed in miniature inside each cell. Formulas for cells are written in a programming language that includes operators for array manipulation, image processing, and rendering. Formulas may also contain control structures, procedure calls, and assignment operators with side effects.

Compared to flow chart visualization systems, spreadsheets are more expressive, more scalable, and easier to program. Compared to numerical spreadsheets, spreadsheets for images pose several unique design problems: larger formulas, longer computation times, and more complicated intercell dependencies. We describe an implementation based on the Tcl programming language and the Tk widget set, and we discuss our solutions to these design problems. We also point out some unexpected uses for our spreadsheets: as a visual database browser, as a graphical user interface builder, as a smart clipboard for the desktop, and as a presentation tool.