In Printing Preferences, choose the Layout tab, then click on the 'Advanced' 
button. 
advanced.jpg (37.8 K)
Under Document Options you will find the Bitmap Format selections. 
format.jpg (177.8 K)
Here you can specify the type of TIFF format that you want to use. 
TIFF Black/White Group 4, multi-strip TIFF Black/White Group 4, single strip 
(default), 24-bit Color Packbits (True Color) , 8-bit Color Packbits 
(256 Colors), 4-bit Color Packbits (16 colors) ,
(LZW support available on Request). 24-bit color requires an enormous 
amount of memory. If your system does not have sufficient memory to create 
the color output file, it automatically reverts to black and white output. 
For color output, minimize the memory requierment, use a lower resolution, 
or use the 8-bit color. The 4-bit color mode is specially useful for Excel 
spreadsheets that have charts or graphics.