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Digital BW, The Print

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Re: [Digital BW] QTR/Linux with UltraTones/2200: gray ramp question

2003-11-15 by Carl Schofield

David,

The Ultratone profiles you have were made before the dot size weighting  
change.  You might want to re-check the partitioning with the full  
calibration procedure.

Carl
On Friday, November 14, 2003, at 05:50  PM, David Wroblewski wrote:

> Sorry to be taking up so much bandwidth on the group while
> converting my 2200 from UltraChomes to UltraTones. I'm almost
> there, but I have a question about getting that last few percent
> of precision out of my setup before I start seriously burning through
> ink and paper. To be clear, this QTR on Linux, with a Epson 2200.
>
> Background: I've installed the UltraTone carts, cleaned & checked
> the nozzles until they are firing perfectly. I have the toner-curve.raw
> file with the correct bit order for Linux. I've installed Carl's 2200
> UT curves, and relinearized them, but did not do the calibration
> procedure from scratch, only entered the new linearization data.
>
> Problem: The output is wonderful, and ALMOST perfect. What prevents
> it from being perfect is that when I print 21step.tif I see a tiny
> discontinuity in the gray ramp, located at a slightly different spot
> for each curve (cool, warm, sepia, neutral), somewhere between 50%
> and 60%. On neutral it is barely visible; on warm, I can spot it with
> a quick scan.
>
> A while back I modified the 2200 dot size transition point in my QTR  
> code
> to be 0.45 when I saw a similar, but far more pronounced, problem using
> the Epson UltraChomes. The change made the resulting UltraChrome gray  
> ramp
> absolutely 100% perfectly smooth, without any discontinuity. I'd like
> to get to the same place with UltraTones, since I know it is possible.
>
> Questions:
>
> - Should I be recalibrating from scratch instead of just relinearizing?
>   I would think that wouldn't be necessary, otherwise how can we share
>   curves? I don't think I recalibrated with Carl's UC curves.
>
> - Might the optimal dot size transition point vary between ink sets on
>   the same device? I haven't tried changing it yet, but I would be
>   happy to do so if that's the problem. Simple enough.
>
> - Is my expectation wrong, that the ramp should be totally smooth?
>   I have no evidence this is image-affecting, though I could posit an
>   image in which it might visibly manifest. It would tell me
>   a lot if, for example, other folks who've been through this said,
>   "Yeah, that happens, don't sweat it. Shut up & print." Or the  
> opposite.
>
> Thanks for all advice. I'm soooo close to nirvana....
> david
>
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>
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