Digital BW, The Print

I use QTR 2.5.1.0 with an Epson 2200 and matte paper. I've printed so 
far with 280 dpi (a 3018x20010 pixel file printed on a letter size 
paper to about 10.76x7.17") and noticed a slight loss of contrast as 
compared to using the Epson driver. To compensate for this loss of 
contrast I've applied and S-curve with 3 points on the curve: 64/58, 
128/128 and 192/198. So far so good.

When I print with 305 dpi I notice a greater loss of contrast that 
would require a more aggressive S-curve. I would expect the same 
tonality across a wide range of dpi's. What is happening? Would 
switching to the newer QTR 2.5.2.1 resolve this problem?

Somewhere, sometime ago, I read that Epson printers want to print only at
the canonical resolutions of 2800 dpi and it divisors, i.e., 2800, 1440,
720, 360, 180.  When any other resolution is chosen, the driver resamples to
one of the canonical values.  According to this theory, choosing two
different resolutions to print the same image could result in different
resampling paths, therefore different, tonal results.  I have absolutely no
idea whether this is myth or fact.

Furthermore, even if true, since you are using QTR rather than the Epson
driver, it would seem not to apply.  I throw this out not so much as to
solve your problem as to fish for additional information from this very
knowledgeable group.

Harry


On 9/30/07 2:02 PM, "Frans Waterlander" <frans2001@...> wrote:

> I use QTR 2.5.1.0 with an Epson 2200 and matte paper. I've printed so
> far with 280 dpi (a 3018x20010 pixel file printed on a letter size
> paper to about 10.76x7.17") and noticed a slight loss of contrast as
> compared to using the Epson driver. To compensate for this loss of
> contrast I've applied and S-curve with 3 points on the curve: 64/58,
> 128/128 and 192/198. So far so good.
> 
> When I print with 305 dpi I notice a greater loss of contrast that
> would require a more aggressive S-curve. I would expect the same
> tonality across a wide range of dpi's. What is happening? Would
> switching to the newer QTR 2.5.2.1 resolve this problem?
> 
-- 

Harry F. Lockwood




[Non-text portions of this message have been removed]

1) Do we know that the "canonical" dpi are controlled
by the printer driver? 

I had thought, for no good reason, that factor was in
hard-wired, irrespective driver.

2) When DPI drops below a certain point I lose certain
tones (including fine details)...this doesn't actually
increase contrast but causes a "punchy" effect, good
for tiny prints...

Black Only does something similar. IMO its coarseness
(abandons tonality between dots) can chop the tonal
spectrum without increasing overall contrast...

...like taking the highs out of music without changing
the mid and bass: sounds great in an old car's AM
radio, less great on a fine system. 

...Black Only and low DPI can make unsharp
images/files seem acceptable in small prints by simply
terminating resolved information before the softness
sets in.

JK