Digital BW, The Print

Steve Kale wrote:

>I'd like to revisit the question of profiling these printers. In normal
>colour mode presumably the printer just operates as an 8 channel device and
>the driver does a CcMmYKlKllK separation when it receives the RGB file.  But
>how would one profile the B&W mode?  Arguably one should send a test chart
>to the printer, print it in this mode, read the patches and calculate a B&W
>Mode profile.  But I don't see how this part can be done by conventional
>profiling software.  So we can profile Colour Mode but not B&W Mode?
>
>  
>
One possibility is that they used used an (extra) edited color profile 
that has got the "unsaturated" treatment on all the renderings. Combined 
with special paper settings for B&W (but still related to the color 
paper settings for the same paper) with the most aggressive GCR black 
generation in it you will get no color ink used in the B&W print while 
the profile can be based on the color paper settings. Given the fact 
that printer can be fed with a neutral RGB file or a Greyscale file in 
B&W mode suggests that something like that is used.  I bet it actually 
makes an RGB file of the Greyscale in the driver again like the Epson 
drivers do with CMYK files already. The toner addition can overrule the 
CM so sepia etc remains possible..

Reading the information again I start to doubt whether it actually has 
linearising features in the driver. It mentions linearisation at the 
factory and combined with Atkinson like profiles that would be good 
enough for most but not for the long run and third party papers. Custom 
profiling can take care of smaller linearisation shifts in time.

Better keep QTR on your system if it isn't working nice on B&W.

Ernst