[argyllcms] Re: chartread feature request / pipedream...

  • From: Klaus Karcher <lists@xxxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 08 Jul 2010 10:12:29 +0200

Graeme Gill wrote:
But I'm more interested in why you need to use this approach. Do
you think strips get misread ? Do the patch values vary a lot with
each attempt at reading ? Is the instrument moving too fast ?

Radek Doulik wrote:
I can report similar problems with i1 reading as well, and IIRC even
with DTP20. I noticed that when I was reading charts containing only
gray patches (say targen -d 0 -s 52). I have a tool to display the
measured values and sometimes some of the values are completely off. It
usually helps to reread the chart again.

First I thought it might be broken bi-directional detection, but it
happens even when running chartread with -B parameter. My (wild) guess
is that it incorrectly detects the beginning of row, might be something
else though. So when I read it second time I try to put the instrument
close to the beginning of the row.

From my experience, giving the eye-one a short rest at the beginning of each strip seems to improve the reliability significantly. (i.e press the instrument switch and then wait for approx. 1-2 sec before you start moving the instrument). Maybe this has to do with the black calibration at the beginning of the strip.

But admittedly, it's still hard to get measurements with a really high repeatability from an eye-one in strip mode: a worst case Delta E 2000 below 1 between two subsequent readings of a big chart is more exception than rule in my experience (with Argyll as well as with XRite software).

I'm excited about whether the new patch slicing algorithm can improve the repeatability.


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