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List:       gimp-print-devel
Subject:    Re: [Gimp-print-devel] Printer Tuning
From:       Robert L Krawitz <rlk () alum ! mit ! edu>
Date:       2004-11-13 0:43:57
Message-ID: 200411130043.iAD0hvKR006381 () dsl092-065-009 ! bos1 ! dsl ! speakeasy ! net
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   From: Mark Tomlinson <mtomlinson@caverock.net.nz>
   Date: Sat, 13 Nov 2004 13:37:42 +1300

   I have just spent some time tuning my Epson photo 830, and thought
   the results might be useful to some others. As I have been using
   3rd party inks rather than Epson originals, the results might not
   apply to everyone (or even anyone) else.

   The first problem was the balance between Cyan, Magenta and Yellow
   (I was only printing in 4-color at this stage). Every Epson I have
   used (genuine inks or otherwise) always seems to print greenish. By
   setting C/M/Y balance controls to 0.9/1.15/0.9, a grey scale
   printed much better. Does anyone else agree that something like
   this should be a default?

It's possible, although third party inks do tend to differ somewhat.

   Next, I added in the photo inks. The pale greys turned blue,
   indicating that the density settings for the photo inks wasn't
   right. Changing the values in photo_gen2_shades from 0.29 to 0.35
   solved this. I see that these are the settings in
   photo_gen3_shades, but don't know if (a) the 830 is in the wrong
   category, or (b) the 3rd party inks are different from the Epson
   ones.

The 830's in the right category for this purpose, I'm quite sure.
I've definitely seen differences in third party inks for this purpose.

Can you get some Epson inks and retry this tuning?

   Note that changing the balance controls doesn't require any driver
   changes - there are settings for this, whereas the photo ink
   settings require me to re-compile. As much as I don't like adding
   more and more controls, I think this is important as we are always
   likely to have errors somewhere in the drivers considering the
   number of models that are supported.

   These two tunings produced much better looking output. I can at
   last appreciate the improvements made to the color conversions. I
   tried a photo of some lavender, and the purples printed fairly
   weakly. The following change to escp2-papers.c makes it look much
   better. These are some saturation values I worked out a while ago,
   and probably aren't ideal given the new code and hue
   adjustments. In particular, I think there's a bit much in the
   yellow/green area.


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