Although Tcl/Tk is widely distributed in engineering and graphical applications, its use in imaging and visualization is recent. In this paper, we described a new gray-scale widget and its use in visualization of large data sets. Although it relies on a interpreter, its speed compares favorably with typical X-Motif self-contained applications, as we implemented an efficient management of data and colors. Designing high level commands and combining hypertools helps perform tedious tasks automatically, thus increasing the interaction efficiency. We plan in the near-future to enhance our image processing library and to port the code to Windows and Mac. The Tcl7.5 sockets will also be used to develop distributed visualization applications for the Internet.