In message <Marcel-1.53-0117204657-0b0ZSTv@xxxxxxxxxx>, Anthony Hilton <ajh@xxxxxxxxxxxxxxxxx> writes
Tha answer to David's question is that each dot at 600 dpi is either total toner of the colour or total nothing - the printer achieves shades by using more or fewer of the dots in an area. Printing direct from the computer the software handles this for you to the best capability of the printer.
HP Printers have "resolution enhancement technology" or RET. A quick Google just now seems to suggest that it allows the printer to put down half a dot by changing the laser power.
This is from a HP web site:"Hewlett Packard created "resolution enhancement technology"—or RET—to correct this. RET inserts smaller dots at the edges of lines to smooth the rough edges. RET does not improve the resolution but the document looks better. "
It all brings back the Computer Concepts Laser Direct, wasn't there some story about that - how they managed to get 600dpi out of a 300dpi laser engine?
HP go on to say:"Full-color laser printers tend to be much more expensive than black-and-white versions and require a great deal of printer memory to produce high-resolution images. But oh, the color! HP LaserJet printers can provide true 600 x 600 dpi output (the equivalent of 1200 dpi) with HP ImageRet 2400, for crisp text, bold graphics and vivid pictures. "
which is opaque.Given the technology in modern printers (e.g. error diffusion instead of half toning) it is hard to give a fixed value for the resolution. Gavin Crawford got it right - see if changing the resolution makes a visible difference.
One other point there's no point in scanning at a much higher resolution than the original material.
I remember when I got my first scientific calculator, I'd painstakingly write down every calculation to 10 decimal places. I just couldn't bear to throw away all that data. Eventually someone hurt my feelings by pointing out that most of those digits were rubbish - if you can only measure stuff to the nearest millimetre there's no point worrying about nanometres.
-- David Pilling email: david@xxxxxxxxxxxxxxxxxxx web: http://www.davidpilling.net post: David Pilling P.O. Box 22 Thornton Cleveleys Blackpool. FY5 1LR UK fax: +44(0)870-0520-941
