To write some image data (image) to a file (outfile) in TIFF format all you have to do is type the following for grey scale: IDL> tiff_write, outfil, image For 256 element (pseudo) color, use: IDL> tiff_write, outfil, image, red=r, green=g, blue=b where the optional parameters red, green and blue are used to save the color table characterized by the byte arrays (r, g, b - see TVLCT for details about obtaining them).
To make full (24 bit) color TIFF format files see the documentation for TIFF_WRITE (i.e. use the DOC_LIBRARY utility on TIFF_WRITE).