QTR-Quadtone RIP

I'm printing on EPSG with Daniel Staver's PKN-GLOP curves and getting 
very fine lines in shadow areas. I'm printing on an Epson 2100 with 
MIS UT inks (and using PKN obviously).

I believe the banding is present throughout the print but only 
visible in shadow areas. So the net effect is a very fine, almost 
scratch like pattern of horizontal lines that are parallel to the 
movement of the print head and appearing in the deep shadows.

Print head nozzle checks are consistently fine (although cannot check 
the Y obviously as it has GLOP). I've tried reducing the ink limit of 
the GLOP but this has no effect. 

I've seen this now with two different images and am stumped. Does 
this ring any bells for anyone?

Printing tiff files processed out of Qimage and using 1440 
better/ordered in QTR. Not running absolutely latest version of the 
GUI - I think 2.2 f for QTR and 2.3.? for the GUI...

Best,

Dave Meddings

There was some discussion on the BWPrinting list of possible deficiencies in
the dither algorithm used by Gimp Print (part of QTR). One suggestion was to
add some Gaussian noise to the shadows.

Tom Moore

> -----Original Message-----
> From: QuadtoneRIP@yahoogroups.com [mailto:QuadtoneRIP@yahoogroups.com] On
> Behalf Of David Meddings
> Sent: Monday, October 31, 2005 5:30 AM
> To: QuadtoneRIP@yahoogroups.com
> Subject: [QuadtoneRIP] Banding with semi-gloss printing
> 
> I'm printing on EPSG with Daniel Staver's PKN-GLOP curves and getting
> very fine lines in shadow areas. I'm printing on an Epson 2100 with
> MIS UT inks (and using PKN obviously).
> 
> I believe the banding is present throughout the print but only
> visible in shadow areas. So the net effect is a very fine, almost
> scratch like pattern of horizontal lines that are parallel to the
> movement of the print head and appearing in the deep shadows.
> 
> Print head nozzle checks are consistently fine (although cannot check
> the Y obviously as it has GLOP). I've tried reducing the ink limit of
> the GLOP but this has no effect.
> 
> I've seen this now with two different images and am stumped. Does
> this ring any bells for anyone?
> 
> Printing tiff files processed out of Qimage and using 1440
> better/ordered in QTR. Not running absolutely latest version of the
> GUI - I think 2.2 f for QTR and 2.3.? for the GUI...
> 
> Best,
> 
> Dave Meddings
> 
> 
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
>

OK good to know you are back from Shanghai Daniel.

Thanks to you and Tom for some suggestions which I'll try.

All the best,

Dave Meddings

Just had a chance to test a few sheets of Cranes new Museo Max paper.

Fairly unscientific, but:

I am finding this a very nice paper.

Close to as sharp/crisp as Arches Infinity which, imo is one of the best in
that regard.

The texture is on the verge of being too much for me, but not quite (might
be an issue with lots of smoothy sky area in prints) - close to the Epson
Watercolour - maybe not quite as much

Other than that it does give very nice blacks - it has to be one of the best
couple of papers (using Epson UC inks but with MIS ebony black via QTR).

Best of all I find it has a very neutral paper base. It is very slightly on
the warm side, but it probably gives the most "neutral" b&w/grey of any
paper. I can't detect any tendency towards the horrible "magentarism" that
many paper base/coatings give under mixed light, nor any tendency towards
green - even with straight Quad inks. For me, along with the nice blacks
that neutral nature of the paper is a big plus.

I only got six sheets to try, so I can't do much more testing, but this
paper is in the top two or three for me along with Arches Infinity
(smoother) and Dourian Fine Art by Red River (some OBA's). (if only it had
slightly less
texture it would possibly be #1).

It's not the magic bullet or a quantum leap - but as far as blacks go, it
appears one of the best.

For now it's only available in rolls and larger sheets - smaller sizes are
supposed to be in the pipeline

Also there are colour profiles on the Crane site, which I haven't' tried
yet)

tim a


tim

> I'm printing on EPSG with Daniel Staver's PKN-GLOP curves and 
> getting very fine lines in shadow areas. I'm printing on an 
> Epson 2100 with MIS UT inks (and using PKN obviously).
> 
> I believe the banding is present throughout the print but 
> only visible in shadow areas. So the net effect is a very 
> fine, almost scratch like pattern of horizontal lines that 
> are parallel to the movement of the print head and appearing 
> in the deep shadows.

This happens to me when using any one of the lower quality 1440dpi
resolutions. Have you tried all the various quality combinations at 1440dpi
to see if some of them are better than others?

I'm back from Shanghai by the way. I'll post updated curves when I get back
to the office tomorrow.

--
Daniel Staver
http://daniel.staver.no

Quick followup on my own issue:

Trying various dithering algorithms with 1440 super or 1440 (both at 
the better setting) had no effect.

Printing at 2880 got rid of microbanding but introduced major bronzing

Adding 12.5% monochromatic gaussian noise to the shadows and printing 
at my normal settings solved the problem.

So thanks to Tom Moore and indeed it looks as if there is an issue in 
the gimp printing side of things.

David Meddings

--- In QuadtoneRIP@yahoogroups.com, "David Meddings" <meddings@f...>
wrote:
>
> Quick followup on my own issue:
> 
> Trying various dithering algorithms with 1440 super or 1440 (both at 
> the better setting) had no effect.
> 
> Printing at 2880 got rid of microbanding but introduced major bronzing
> 
> Adding 12.5% monochromatic gaussian noise to the shadows and printing 
> at my normal settings solved the problem.
> 
> So thanks to Tom Moore and indeed it looks as if there is an issue in 
> the gimp printing side of things.

Very much so. The gimp print drivers will exhibit microbanding
whenever the total ink density (just all all 7 channel curves) exceeds
100%. This is easy to do with a glop curve, since we're typically
adding glop at anywhere from 10-25% to curves that might have an ink
limit at 80%, or black boost up to 100%.

I'm working on a driver with a layering concept as part of GRIP (if
GRIP ever hits the point of being a useful public beta). The glop
would go on an "aligned" layer so glop droplets always end up on top
of colored ink droplets.

gimp print always interleaves ink, nothing ever really overlaps, and
you cannot exceed 100% coverage (inks just displace each other, which
can be a really, really weird looking effect when glop displaces black).