http://www.purl.org/tcl/home/man/tcl8.4/TkCmd/image.htm
Someone want to mention the Img extension and why it is so useful?
See also Buttons with image and text Images With Transparency and Plain Images Reading GIF image dimensions Reading JPEG image dimensions Reading PNG image dimensions image create photo -file ./fun.gif Tk image Dos and Don'ts -
Tk syntax help - Arts and crafts of Tcl-Tk programming - Category Command