QTR-Quadtone RIP

Roy Harrington wrote:

>
>I don't know for sure what this AMC is but here's my guess.  The major issue to
>deal with to get smooth results is the physical variation of the 180 jets/ink.  That's
>a lot of jets and manufacturing tolerances can go so far.  The major solution has
>been the weaving methods (as above).  As long as you vary which jets are used on
>a line there's less chance the one jet that is off (bigger or smaller) will show to the eye.  
>
>My guess is that in the factory they just measure all the jets to see the variation.
>This sounds complicated but the auto nozzle check does much of what you need.
>Each patch is printed with only one nozzle so you can measure the density of each
>patch to get an idea of the nozzle variation.  Then you burn into the firmware a
>table of the variations.  At print time, you give a "big" nozzle a little less voltage and
>a "small" nozzle a little more voltage.  Overall you ought to be able to reduce the
>variation of nozzle dropsizes.  Just a guess but it fits the description.
>  
>

The text more or less implies it is done on the fly while printing.

>  
>
>>Joseph Holmes has this on screening of the new Pro models:
>>
>>8) The screening technology has been overhauled for color, to 
>>accommodate the improved precision of the new print head. The screening 
>>for the Advanced Black & White mode is of course all new and does an 
>>amazing job of creating consistent coloration throughout the tone scale 
>>and superb smoothness on photographic papers (e.g. Premium Luster). 
>>Smooth results on rag papers are much easier to achieve.
>>
>>
>>Ernst
>>    
>>
>
>The B&W mode obviously uses less color inks just like QTR has always done.
>Smoother is by far a result of having and using the light-light-black ink.
>These ARE very good improvements and worth touting for in the 
>standard Epson driver.
>  
>
I think Joseph is a bit more involved than he admits in his review. This 
is the first report of a 9800 user, quite frank in its details and with 
Epson's approval . There's some analogy  in the use of cmY composite 
greys along the Kkk ink core (as observed by Paul Roark) to the Small 
Gamut inks invented by Joseph and made by Lyson.  The order of the 
printer heads has changed too compared with the from left to right usual 
order of KCMcmY that has been a 10 ? years old convention, the order for 
the 9800 now is Light Light Black, Light Magenta, Light Cyan, Light 
Black, then on the right end Black, Cyan, Magenta, Yellow. So when 
Joseph writes that the screening technology is overhauled for color I 
tend to believe that and I think he got that information first hand.

It will not make a difference to QTR one would think but possibly one of 
the other dithering methods may suite the changed pattern of weaving 
better or a new one will fit the changes better. Robert Krawitz probably 
will check what actually has changed in the lay down of the inks. The 
Gimp-print solution for that has always been made for color printing in 
the first place. You will best know whether that could be improved for 
B&W but most likely it is good enough as it is.

http://www.josephholmes.com/news.html

Ernst