[argyllcms] Re: [Possible bug in Spyd2.c] Inconsistant readings from Spyder3

  • From: Roger <graxx@xxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 06 Mar 2009 07:43:19 -0500

Keep in mind that any relatively inexpensive emissive instrument is going to
have problems in reading extreme low light, that's the hallmark of
inexpensive. I was once told by Danny Rich that, what we're asking is for
the instrument to read practically no light -- very difficult to detect few
photons reliably. So, personally, anything below 1 cd/m2 I tend to take with
a grain of salt. BTW, for those who are interested in the EyeOnePros, I was
told that if they are held about 5 cm off the screen, a) they won't exhibit
any thermal drift whatsoever and b) the readings will not be significantly
different from those obtained by contact measurements.

But thank's for your code modification for the Spyder3.


> Hello again!
> As I wrote in the last post I have found a possible bug in Spyd2.c.
> Spyder3 has problems with reading a very dark patch and can sometimes
> return garbage:
> To confirm the bug try reading a completely black patch a few (10?)
> times with spotread and you will see that the results are something
> like (for X axis):0.2, 0.19,0.2, 0.17 [so far OK], 0.01 [Stupid
> reading!],
> 0.2, 0.19 [etc.]. The problem is IMHO caused by too small reading time
> in spyd2.c. When I

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