Digital BW, The Print

Austin-


> Hi Kevin,
>
>> 1. Does anyone know what the resolving power of the Epson printers are
>> (4 lp/mm 10lp/mm, 20 lp/mm)?
>
> Depends on the printer.  You can do the math...if it's a 720DPI 
> printer,
> that's 360lp/inch, divide that by 25.4, or 14.7 lp/mm.

Yes, I can do the arithmetic but that seems to be a theoretical 
maximum.  What if the line pairs are grey.  I thought that the 720DPI 
is 720 printer dots per inch and it takes several printer dots to make 
a grey.  Doesn't dithering reduce this number.

I have printed the 21step greayscale that someone provided (Paul 
Roark?) which has small line pair patterns on it.  At 3.6 lp/mm the 
contrast is high and the lines obvious, at 7.2 the contrast is very low 
the lines are not distinct at all.  Under a loupe the vertical lines 
are much worse than the horizontal.  In practical terms is seems to me 
that the resolving power is much less that 14.7.

It also seems to me that the printers resolution is dwarfed by every 
other upstream component and I wonder whether you could even tell the 
difference between a good lens and an adequate lens in an inkjet print. 
  Or whether, for a fixed print size, you could tell the difference 
between a 4000dpi scan and a 2000dpi scan?

>
>> 4. Do papers have a significant impact on resolution/sharpness number
>> of tones rendered and tonal transition
>
> Resolution/sharpness, yes.  Number of tones, probably minimally, and 
> tonal
> transition...not sure what you mean.

For the numerically inclined it would be interesting to construct 
MTF(like) charts for paper/printer/driver combinations.

--
Kevin