QTR-Quadtone RIP

I am sorry that I do not monitor this site very often. Piezography has
its own Yahoo Groups; one for desktop users and one for Pro users. I
tried to upload a portion of the test file to this group just now, but
Tiff files are not supported. I will type an instruction at the end of
this message on how to obtain a portion of high resolution type example.

I have not read all the comments. But I gleamed that someone tried to
make a small type file in Photoshop at 360 or 720 dpi and both may not
be much of a challenge. Its not that the resolution is not high
enough, but that Photoshop makes very forgiving type. Its just not
much of a challenge to a print system. The files which we printed in
the demo are not made in Photoshop. It is purely vector art and most
of the type is wrapped around objects and necessarily extremely high
resolution, because so much text is required in the artwork. 

The first project we did was all of the known texts attributed to Ben
Franklin which were wrapped around all of the engraved lines of a $20
bill. The next test was the Alice in Wonderland text.

I think a test like this may not relate to the average user, but it
still demonstrates high resolution. An example of when high resolution
printing is necessary is when a photographer wishes to realize
definition from large format negatives which are drum scanned. 

At Cone Editions we typically drum scan sheet film at 1080dpi. We
never rez up or down and allow the QTR driver with a Piezography
Profiler made set of curves do the printing. Our goal in doing
something like this is to print truly tac sharp at enlargement.

This test will be lost on those who only process digital camera files
or use desktop scanners to scan film. If however, you have 4x5 or
larger film and print 20x24. Then extremely high resolution printing
would definitely benefit you. Especially, if your film is fine grain.
And fair to say, Cone Editions does an extreme amount of printing for
large format film photographers.

If you do not need to print high resolution there are still many
benefits to seven shades of ink versus using only four or the
multi-toning ink sets.

But in any event - I posted a 1/2 inch square file to the inkjetmall
website that you can download if you would like to test it against
your own process, or to try Piezography K7 with it. Just realize that
it will only be a 1/2 square when printed. And yes of course you need
a loupe to read it. That is the intention!  :)

Download at http://www.inkjetmall.com/piezoTypetest_tif.zip

And if you want to get my attention - please post a message for me at
the Piezography Desktop User Group at
http://tech.groups.yahoo.com/group/piezography3000   I usually monitor
that list on a daily basis. However, I will check on this list over
the next few days to see your results of the comparisons to this type
of text.

best regards,

Jon Cone

Jon Cone wrote, in part:

>... I posted a 1/2 inch square file ...
>  if you would like to test it ...

> Download at http://www.inkjetmall.com/piezoTypetest_tif.zip

I just tried printing this on an Epson 1400 with QTR and the Epson driver.
It's very sharp with either.  The text actually looks a little larger than
the "1 point" text I had printed earlier.

I'm not sure what QTR does with a 1080 dpi file.  I think the Epson driver
downsizes it to 720.  That might actually be a source of difference that
could affect the K3 example.  I've experimented with very high resolution
files in the past and noticed that the information thrown out by the Epson
driver (I forget what printer model) made the very high resolution file
print less well than one that was "only" 720.  That is, there may be a
difference in how the approaches treat very high res files.

At any rate, while high resolution scans are wonderful, I can't imagine
anyone wanting to deal with or needing a file in excess of 720 ppi at the
print size.  The 20,000 pixel wide panorama file I just printed was such a
nuisance to deal with and print at its full resolution that I downsized to
240 ppi for the 51 inch print.

Paul
www.PaulRoark.com

Paul Roark wrote:
> Jon Cone wrote, in part:
> 
>> ... I posted a 1/2 inch square file ...
>>  if you would like to test it ...
> 
>> Download at http://www.inkjetmall.com/piezoTypetest_tif.zip
> 
> I just tried printing this on an Epson 1400 with QTR and the Epson driver.
> It's very sharp with either.  The text actually looks a little larger than
> the "1 point" text I had printed earlier.
> 
> I'm not sure what QTR does with a 1080 dpi file.  I think the Epson driver
> downsizes it to 720.  That might actually be a source of difference that
> could affect the K3 example.  I've experimented with very high resolution
> files in the past and noticed that the information thrown out by the Epson
> driver (I forget what printer model) made the very high resolution file
> print less well than one that was "only" 720.  That is, there may be a
> difference in how the approaches treat very high res files.
> 
> At any rate, while high resolution scans are wonderful, I can't imagine
> anyone wanting to deal with or needing a file in excess of 720 ppi at the
> print size.  The 20,000 pixel wide panorama file I just printed was such a
> nuisance to deal with and print at its full resolution that I downsized to
> 240 ppi for the 51 inch print.
> 
> Paul
> www.PaulRoark.com 



Drivers have improved on upsampling but few on downsampling. 
Good anti-aliasing routines could improve the output of 
downsampled images like they do in Qimage. Not only is the 
detail compromised but contrast can be exaggerated without 
the right anti-aliasing, depending on the detail/texture of 
the image content.   If you like to scan once at the highest 
resolution you can afford (equipment or third party scan) 
you will be faced with the fact that downsampling has to be 
done from time to time for smaller prints. If the driver has 
to do it or just an image editor you may encounter problems, 
you better check what the quality of anti-aliasing is in the 
program you use and whether it does the up- and dowsampling 
to the native resolution before the driver does it.

For text it has been my experience that even with a rough 
driver like the Epson 9000 one the quality of the characters 
can be very high if you let Photoshop rasterise fonts (for 
example a PDF with vector fonts dropped in Photoshop) to 720 
PPI and print that raster image. In the 9000 driver it will 
be downsampled to 360 PPI native resolution. most likely 
with a nearest neighbour routine. That's very nice for that 
content but not for photographic images. On the other hand 
Qimage doesn't do it as nicely on fonts or you switch the 
extrapolation  routine to the worst one or simply off.

Roy has always been vague about the native resolution of 
QTR. More or less writing that it doesn't exist.

-- 
Met vriendelijke groeten,  Ernst


|  Dinkla Grafische Techniek  |
|     www.pigment-print.com    |
|             ( unvollendet )            |

Hi Ernst,

I don't remember being vague about QTR.  QTR resamples all input files
to 720x720 pixels.
Then dithering is done to whatever dpi you've selected -- mostly
2880x1440 or 1440x720.
A couple printers also have 1440x1440.

The resampling to 720x720 is done by the OS on the Mac so I'm not sure
of the algorithm.
On the PC it's a bi-linear algorithm -- basically two linear
interpolations -- horizontal then
vertical.  As far as I know all the Epson drivers do either 360x360 or
720x720 resampling.
In general the smaller printers tend to do 720x720 and the larger ones
do 360x360.  If the
driver has a Finest Detail switch that gives the user a choice between
these resamplings.

----------

While I think this "small text experiments" are interesting and
definitely show some differences,
you can read too much into the results.  If you look at the actual
input files that Paul, Jon
and others are using you can see that one-point text can look very
different even before
you print it.  Anti-aliasing for text is complicated balance between
sharpness and smoothness.
Readability is also a tricky evaluation.  One eyes fill in details
much of the time. Choice
of font makes a huge difference -- some lend themselves to small type
much better than
others. The angle has an effect too.

BTW, I agree with Paul that for some reason the size of his 1pt text
is different than Jon's
1pt text.  Jon's font appears to be a simpler font, too.

BTW again, take Paul's file and just insert a 1pt Verdana, no aliasing
and the difference is
very dramatic.   (not sure why Paul did 7200dpi and reduced it).

Roy

On Tue, Sep 2, 2008 at 8:10 AM, Ernst Dinkla <edinkla@...> wrote:
> Paul Roark wrote:
>> Jon Cone wrote, in part:
>>
>>> ... I posted a 1/2 inch square file ...
>>>  if you would like to test it ...
>>
>>> Download at http://www.inkjetmall.com/piezoTypetest_tif.zip
>>
>> I just tried printing this on an Epson 1400 with QTR and the Epson driver.
>> It's very sharp with either.  The text actually looks a little larger than
>> the "1 point" text I had printed earlier.
>>
>> I'm not sure what QTR does with a 1080 dpi file.  I think the Epson driver
>> downsizes it to 720.  That might actually be a source of difference that
>> could affect the K3 example.  I've experimented with very high resolution
>> files in the past and noticed that the information thrown out by the Epson
>> driver (I forget what printer model) made the very high resolution file
>> print less well than one that was "only" 720.  That is, there may be a
>> difference in how the approaches treat very high res files.
>>
>> At any rate, while high resolution scans are wonderful, I can't imagine
>> anyone wanting to deal with or needing a file in excess of 720 ppi at the
>> print size.  The 20,000 pixel wide panorama file I just printed was such a
>> nuisance to deal with and print at its full resolution that I downsized to
>> 240 ppi for the 51 inch print.
>>
>> Paul
>> www.PaulRoark.com
>
>
>
> Drivers have improved on upsampling but few on downsampling.
> Good anti-aliasing routines could improve the output of
> downsampled images like they do in Qimage. Not only is the
> detail compromised but contrast can be exaggerated without
> the right anti-aliasing, depending on the detail/texture of
> the image content.   If you like to scan once at the highest
> resolution you can afford (equipment or third party scan)
> you will be faced with the fact that downsampling has to be
> done from time to time for smaller prints. If the driver has
> to do it or just an image editor you may encounter problems,
> you better check what the quality of anti-aliasing is in the
> program you use and whether it does the up- and dowsampling
> to the native resolution before the driver does it.
>
> For text it has been my experience that even with a rough
> driver like the Epson 9000 one the quality of the characters
> can be very high if you let Photoshop rasterise fonts (for
> example a PDF with vector fonts dropped in Photoshop) to 720
> PPI and print that raster image. In the 9000 driver it will
> be downsampled to 360 PPI native resolution. most likely
> with a nearest neighbour routine. That's very nice for that
> content but not for photographic images. On the other hand
> Qimage doesn't do it as nicely on fonts or you switch the
> extrapolation  routine to the worst one or simply off.
>
> Roy has always been vague about the native resolution of
> QTR. More or less writing that it doesn't exist.
>
> --
> Met vriendelijke groeten,  Ernst
>
>
> |  Dinkla Grafische Techniek  |
> |     www.pigment-print.com    |
> |             ( unvollendet )            |
>
> ------------------------------------

Roy Harrington wrote:
> Hi Ernst,
> 
> I don't remember being vague about QTR.  QTR resamples all input files
> to 720x720 pixels.
> Then dithering is done to whatever dpi you've selected -- mostly
> 2880x1440 or 1440x720.
> A couple printers also have 1440x1440.
> 
> The resampling to 720x720 is done by the OS on the Mac so I'm not sure
> of the algorithm.
> On the PC it's a bi-linear algorithm -- basically two linear
> interpolations -- horizontal then
> vertical.  As far as I know all the Epson drivers do either 360x360 or
> 720x720 resampling.
> In general the smaller printers tend to do 720x720 and the larger ones
> do 360x360.  If the
> driver has a Finest Detail switch that gives the user a choice between
> these resamplings.

Roy, with all respect, I have asked questions about its 
native resolution before and never got an answer as detailed 
as you describe it here. That may have been some years ago 
but I tend to have a good memory for subjects like the one 
discussed here. Never too late though :-) Thank you.

Not so long ago a similar discussion happened on one of the 
other list where the observation was made that smaller 
prints of the same image data tend to have more density than 
larger ones. I actually think it is a shift in contrast and 
the result of aliasing. It is content related.


-- 
Met vriendelijke groeten,  Ernst


|  Dinkla Grafische Techniek  |
|     www.pigment-print.com    |
|             ( unvollendet )            |

>... (not sure why Paul did 7200dpi and reduced it).

For some reason after I manually inserted "1" in the PS Text box it was
reverting back the 6 -- the smallest type size listed.  Now it's holding at
1.  I'm also not sure why it was not cooperating when I did this earlier.
(A 5 year old Dell could be part of the answer.)

I agree these are not particularly useful tests, but it would be interesting
to see if there is any way to duplicate Jon's results with K3 ABW mode
printing.  From what I can see, any of the newer printers at 2880 with
either QTR or the Epson driver produce extremely sharp results.

Paul
www.PaulRoark.com

"Sharpness" varies in QTR: adjust ink loading according to the paper
in question. Excess ink (hoping to obtain maximum black)causes softness.


--- In QuadtoneRIP@yahoogroups.com, "Paul Roark" <paul.roark@...> wrote:
>
> >... (not sure why Paul did 7200dpi and reduced it).
> 
> For some reason after I manually inserted "1" in the PS Text box it was
> reverting back the 6 -- the smallest type size listed.  Now it's
holding at
> 1.  I'm also not sure why it was not cooperating when I did this
earlier.
> (A 5 year old Dell could be part of the answer.)
> 
> I agree these are not particularly useful tests, but it would be
interesting

> to see if there is any way to duplicate Jon's results with K3 ABW mode
> printing.  From what I can see, any of the newer printers at 2880 with
> either QTR or the Epson driver produce extremely sharp results.
> 
> Paul
> www.PaulRoark.com
>

I have also printed the file that was made available o9n the
inkjetmall website.  The resulting text is somewhat smaller than the
1pt text I created (also vector text created in a drawing program --
and also had text in different directions: normal, and at 45 and 90
degree angles).  It does appear that producing the file to 1080dpi
resolution seems to make a difference.  It is significantly different
than my initial comparison with a 360 dpi file.  Since as Roy
explained, both QTR and the Epson driver down samples to 720 dpi (I
used the "Fine Detail" setting on the Epson driver which uses 720
dpi), QTR must be doing something differently than the Epson driver.
And I don't think I am going too far out on a limb, based on my sample
print, that it does it better.  The differences are not as huge as
they are in the promotional Piezography sample print, but it is
unquestionably significantly better.  I am surprised, based on what I
saw before.  Certainly from now on, when printing, if I can send a
file to QTR at 1080dpi, I will.  See a scan of my comparison print of
the inkjetmall file here:
http://tech.ph.groups.yahoo.com/group/QuadtoneRIP/photos/view/d000?b=4&m=f&o=0

Is there any reason to believe that QTR won't produce similar results
with different inksets, such as for example, UT7 and UT-3D?  

While a test like this may be of limited value, it does suggest the
level of detail that is potentially attainable in a print.

Out of curiosity, what is the potential for expanding the QTR software
to similarly handle full color printing?


--- In QuadtoneRIP@yahoogroups.com, "Paul Roark" <paul.roark@...> wrote:
>
> Jon Cone wrote, in part:
> 
> >... I posted a 1/2 inch square file ...
> >  if you would like to test it ...
> 
> > Download at http://www.inkjetmall.com/piezoTypetest_tif.zip
> 
> I just tried printing this on an Epson 1400 with QTR and the Epson
driver.
> It's very sharp with either.  The text actually looks a little
larger than
> the "1 point" text I had printed earlier.
> 
> I'm not sure what QTR does with a 1080 dpi file.  I think the Epson
driver
> downsizes it to 720.  That might actually be a source of difference that
> could affect the K3 example.  I've experimented with very high
resolution
> files in the past and noticed that the information thrown out by the
Epson
> driver (I forget what printer model) made the very high resolution file
> print less well than one that was "only" 720.  That is, there may be a
> difference in how the approaches treat very high res files.
> 
> At any rate, while high resolution scans are wonderful, I can't imagine
> anyone wanting to deal with or needing a file in excess of 720 ppi
at the
> print size.  The 20,000 pixel wide panorama file I just printed was
such a
> nuisance to deal with and print at its full resolution that I
downsized to

> 240 ppi for the 51 inch print.
> 
> Paul
> www.PaulRoark.com
>

I wonder if the odd "overspray" is from a poor down-sampling algorithm.  If
the ABW mode test file is re-sized to 720 in Photoshop does it also exhibit
this characteristic?  The overspray looks like what I'd expect if there were
junk stuck to the head that was deflecting a nozzle.  

 

I noted a comment in another thread that a new printer banded with QTR but
not the Epson driver when the image was too close to the top or bottom of
the page.  This appears to usually be caused by paper transport problems.
The comment made me wonder if Epson has a dither pattern that is made to
hide this type of defect - perhaps at the cost of some sharpness, however.

 

Paul

www.PaulRoark.com <http://www.paulroark.com/>  

___________

 

  _____  

From: momoinu_dc
.
http://tech.
<http://tech.ph.groups.yahoo.com/group/QuadtoneRIP/photos/view/d000?b=4&m=f&
o=0> ph.groups.yahoo.com/group/QuadtoneRIP/photos/view/d000?b=4&m=f&o=0

.



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

Paul-

I just reprinted the, following your suggestion.  The "overspray" was
significantly reduced, but is still present.  The type, itself, was
also a bit better defined.  However, the QTR print of the full 1080dpi
file is still unquestionably superior.  What is it that QTR does
differently (and apparently, better)?

Perhaps what this does show, at the very least, is that when printing
a large file to an Epson printer, downsample to 720 dpi (or 360dpi, as
appropriate)in Photoshop, or other program, before sending it to the
printer.


--- In QuadtoneRIP@yahoogroups.com, "Paul Roark" <paul.roark@...> wrote:
>
> I wonder if the odd "overspray" is from a poor down-sampling
algorithm.  If
> the ABW mode test file is re-sized to 720 in Photoshop does it also
exhibit
> this characteristic?  The overspray looks like what I'd expect if
there were
> junk stuck to the head that was deflecting a nozzle.  
> 
>  
> 
> I noted a comment in another thread that a new printer banded with
QTR but
> not the Epson driver when the image was too close to the top or
bottom of
> the page.  This appears to usually be caused by paper transport
problems.
> The comment made me wonder if Epson has a dither pattern that is made to
> hide this type of defect - perhaps at the cost of some sharpness,
however.
> 
>  
> 
> Paul
> 
> www.PaulRoark.com <http://www.paulroark.com/>  
> 
> ___________
> 
>  
> 
>   _____  
> 
> From: momoinu_dc
> .
> http://tech.
>
<http://tech.ph.groups.yahoo.com/group/QuadtoneRIP/photos/view/d000?b=4&m=f&

> o=0> ph.groups.yahoo.com/group/QuadtoneRIP/photos/view/d000?b=4&m=f&o=0
> 
> .
> 
> 
> 
> [Non-text portions of this message have been removed]
>

That's an interesting set of tests.   The scatter look from the K3 ABW
test is a curious
phenomena.  Since this is the Epson driver I can only guess what's going on.
I highly doubt it has anything to do with resampling.  The extra dots
are just too far apart
to be mechanical spraying, or resample related IMO.  Some diffusion
dither algorithms can
produce that kind of artifact so that would be my guess.  The fact
that the text is diagonal
may help with seeing it.  My prints, all done with QTR, do not show
anything like that --
Ordered Dither which I recommend and use will not produce that kind of artifact.

At least with QTR I'd expect the different inksets, K3, K7, UT7, UT3D
to all perform similarly
in the particular test.  After all we're talking black text here.  To
through out an other idea:
it might be interesting to use a gradient of text from black to very
light gray to see where
the text clarity visibility peters out.

The 1080ppi issue may be because it theoretically gives a thinner
line.  Many of the 720
files show a lot of ink which tends to bleed over.  At 1080 I suspect
the resampling will
end up with a lighter gray so you get less ink on the paper.

Roy

On Wed, Sep 3, 2008 at 6:51 AM, momoinu_dc <LotusM50@...> wrote:
> I have also printed the file that was made available o9n the
> inkjetmall website.  The resulting text is somewhat smaller than the
> 1pt text I created (also vector text created in a drawing program --
> and also had text in different directions: normal, and at 45 and 90
> degree angles).  It does appear that producing the file to 1080dpi
> resolution seems to make a difference.  It is significantly different
> than my initial comparison with a 360 dpi file.  Since as Roy
> explained, both QTR and the Epson driver down samples to 720 dpi (I
> used the "Fine Detail" setting on the Epson driver which uses 720
> dpi), QTR must be doing something differently than the Epson driver.
> And I don't think I am going too far out on a limb, based on my sample
> print, that it does it better.  The differences are not as huge as
> they are in the promotional Piezography sample print, but it is
> unquestionably significantly better.  I am surprised, based on what I
> saw before.  Certainly from now on, when printing, if I can send a
> file to QTR at 1080dpi, I will.  See a scan of my comparison print of
> the inkjetmall file here:
> http://tech.ph.groups.yahoo.com/group/QuadtoneRIP/photos/view/d000?b=4&m=f&o=0
>
> Is there any reason to believe that QTR won't produce similar results
> with different inksets, such as for example, UT7 and UT-3D?
>
> While a test like this may be of limited value, it does suggest the
> level of detail that is potentially attainable in a print.
>
> Out of curiosity, what is the potential for expanding the QTR software
> to similarly handle full color printing?
>
>

momoinu_dc wrote:
> Paul-
> 
> I just reprinted the, following your suggestion.  The "overspray" was
> significantly reduced, but is still present.  The type, itself, was
> also a bit better defined.  However, the QTR print of the full 1080dpi
> file is still unquestionably superior.  What is it that QTR does
> differently (and apparently, better)?
> 
> Perhaps what this does show, at the very least, is that when printing
> a large file to an Epson printer, downsample to 720 dpi (or 360dpi, as
> appropriate)in Photoshop, or other program, before sending it to the
> printer.
>

A year ago I have done several tests with the Qimage 
resolution test target on my Z3100 to check what 
downsampling can do to a print. By changing the size of the 
target image in Photoshop to some sizes smaller and the last 
was a 1200 PPI target, both dimensions halved. That way no 
resampling on the file itself happens in Photoshop so you 
get higher resolution targets without changing their image. 
Printed 1:1, two targets at the same time, one rotated 90 
degrees to see whether paper transport resolution differed 
from head transport resolution. Gloss paper. Qimage was used 
to print and the downsampling to native resolution was done 
either by Qimage or the Z3100 driver with Qimage's 
extrapolation settings off. Some with anti-aliasing on in 
Qimage when Qimage did the downsampling. Some with 
anti-aliasing off. In general all the prints were different 
to one another. Shifts to higher contrast (due to aliasing), 
moir\ufffd building and with the Z3100 driver downsampling, 
disappearence of complete hatched areas where other hatched 
areas became black (aliasing again), etc. Most of that is 
solved by using anti-aliasing routines but the quality of 
the routines differ a lot per application as Bart van der 
Wolf samples already showed a long time ago. Mechanical 
resolution of head or paper transport had little influence. 
The finest line hatches in the 1200 PPI target disappeared 
with Qimage's AA routines and downsampling but the resulting 
gray was equal in tone to the gray of the hatched areas 
where the lines were sharp. No contrast shifts.
The targets are not normal photographs but lines, small text 
etc. However you will see similar things happen in 
photographs depending on the content, texture (grass, corn, 
textile, whatever), scanned grain, etc.

Too often I see statements (LL forum) that one can drop any 
file resolution above say 240 PPI on modern printer drivers 
and it will make optimal use of the data ...... It just 
isn't true. In upsampling nor in downsampling.

http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/down_sample.htm
http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/example1.htm

Qimage targets:

http://www.ddisoftware.com/qimage/quality/

read the article as well there.

As explained above I used the targets in a different way as 
well, sending a 600 PPI target to the printer where the 
driver requested 300 PPI as the native resolution for the 
selected quality setting, sending a 1200 PPI target to the 
printer where the driver requested 600 PPI as the native 
resolution for the selected quality setting.

On small text: if you have anti-aliased fonts for a given 
resolution you will get worse font description when the 
resolution is changed again for that bitmap with fonts. So 
do the rasterisation + anti-aliasing of the vector font at 
the native resolution of the printer with the font size it 
will get in print. Or do it at a resolution twice that of 
the native resolution for really small text (cards etc), 
even a nearest neighbour downsampling will do then. Odd 
sampling ratios make text worse.


-- 
Met vriendelijke groeten,  Ernst


|  Dinkla Grafische Techniek  |
|     www.pigment-print.com    |
|             ( unvollendet )            |

I took up Roy's suggestion that "it might be interesting to use a
gradient of text from black to very light gray to see where the text
clarity visibility peters out."  I did this a few days ago, but
unfortunately haven't had time to post the results until now.

I put a gradient over the 1 point test file to produce all those
shades of gray. I loaded the file to the "Tools" section of the QTR
group webpages.  You can find it here:
http://f1.grp.yahoofs.com/v1/MLTDSAfDErB-gCkHjxMi9KKEOpzpcM4SpgAUohEKbLvO59AXVZskddTJ9UG0j0h3gXN8aRc7F_ht3d4AQmSsCXlFmmCNuWs/Tools/piezoTypetest-gradient.jpg

Printing the file yielded a new set of results.  The QTR-K7 print on
matte paper was clearly superior to the 4800-K3-color ink print on the
same paper.  100% crops of scans of the prints only tell part of the
story, so I've posted the scan of the entire half inch print area in
the "Photos" section.  You can find them here:
http://tech.ph.groups.yahoo.com/group/QuadtoneRIP/photos/browse/5453?c= 
The K3-color ink prints appears to have produced a color cast around
transition of middle gray tones, and some fine banding is evident.  I
wanted to see what Epson's Advanced Black and White (ABW) could do
with this, but since the driver with the 4800 apparently does not
allow ABW to be used on matte paper (does anyone know why this is?), I
printed the test file on semi-gloss paper. Quite frankly, this was the
best print -- better than the QTR-K7 inks -- but I attribute that, at
least in part, to the semi-gloss paper.


--- In QuadtoneRIP@yahoogroups.com, "Roy Harrington" <roy@...> wrote:
>
> That's an interesting set of tests.   The scatter look from the K3 ABW
> test is a curious
> phenomena.  Since this is the Epson driver I can only guess what's
going on.
> I highly doubt it has anything to do with resampling.  The extra dots
> are just too far apart
> to be mechanical spraying, or resample related IMO.  Some diffusion
> dither algorithms can
> produce that kind of artifact so that would be my guess.  The fact
> that the text is diagonal
> may help with seeing it.  My prints, all done with QTR, do not show
> anything like that --
> Ordered Dither which I recommend and use will not produce that kind
of artifact.

> 
> At least with QTR I'd expect the different inksets, K3, K7, UT7, UT3D
> to all perform similarly
> in the particular test.  After all we're talking black text here.  To
> through out an other idea:
> it might be interesting to use a gradient of text from black to very
> light gray to see where
> the text clarity visibility peters out.
> 
> The 1080ppi issue may be because it theoretically gives a thinner
> line.  Many of the 720
> files show a lot of ink which tends to bleed over.  At 1080 I suspect
> the resampling will
> end up with a lighter gray so you get less ink on the paper.
> 
> Roy