QTR-Quadtone RIP

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


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