Digital BW, The Print

Hi David,

Glad to see things are getting better.  I've got a hunch about 
the hitches in the gray ramp:  the 2200 printer has two dotsizes
for 1440x720 resolution.  The gimp-print software has to transition
from one dotsize to the next smoothly and it does this based on a weighting
of the dotsizes.  I have a feeling that gimp-print hasn't had a very accurate
way to measure this weighting, because they've changed it several times
for the 2200.  Below is the code that has this weighting -- the 0.661 is
the important value.  The value should probably be lower, in GP I've seen
it go to 0.56, then 0.50.  I've worked with Carl a bit trying to get a way to
measure it accurately and on his machine 0.46 seemed best.  You can
just edit the source file, recompile and install rastertoprinter-quad.
This will require a re-measurement for the profile.

Roy


---------file: RasterSrc/main/print-escp2-data.c ------------

/***************************************************************\
*                                                               *
*            ULTRACHROME (2100/2200, 7600, 9600)                *
*                                                               *
\***************************************************************/

static const stp_simple_dither_range_t standard_4pl_pigment_dither_ranges[] =
{
  { 0.661, 0x1, 0, 2 },
  { 1.00,  0x2, 0, 3 }
};

DECLARE_INK(standard_4pl_pigment, 1.0);

--------------------



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "David Wroblewski" 
<dawroblewski@y...> wrote:
> Hi all, 
> 
> First a quick update, then a question:
> 
> I've got Roy's QTR software up and cooking under redhat 9.
> Thanks to Roger Sopher and Roy for help and preliminary
> installation notes. Installation was almost painless--we 
> discovered one idiosyncrasy with configuring the CUPS printing
> system, which involved changing some processing rules; I've
> created a file of additional CUPS MIME rules that resolve 
> the issue for me, which Roy and Roger now have.
> 
> I'm driving an Epson 2200 loaded with standard UC inks.
> 
> To get started, I'm printing tif's from Linux using the
> qtcups utility, and the output is lovely. So far, I've sunk
> about a buck (3 blank CD's used to burn the RH9 ISO images)
> and 30 hours of sweat equity into this project. Not a dongle
> in sight, either. :-) I'm using a worthless old PII 333 MHz 
> PC to run RH9. 128 MB memory, 6GB HD.
> 
> Now my question: 
> 
> When I print the 21Step image using the curve EEM_2200-cool I 
> see two very distinct hitches in the continuous ramp, one above
> the 60% patch and one above the 90% patch. After running my first
> calibration series last night, I got the same thing in my own
> profile, shifted to slightly different positions.
> 
> Except for the discontinuity at those two points, the ramp
> looks great, cool and smooth with delicate highlights and a 
> velvety black at 100%. 
> 
> Am I doing something wrong? Do others see this? The settings I 
> used were:
> 
> Dither: Adaptive Hybrid
> Image Type: Photograph
> Ink Type: Seven Color Photo
> Resolution 1440x720 Highest Quality. 
> Blend Curves 1 and 2: 100-0
> Quadtone Rip Curve 1: EEM_2200-cool
> 
> -David