[argyllcms] Re: eye-one pro Rev A/Rev D IR calibration?
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Wed, 30 Jun 2010 23:01:10 +1000
Klaus Karcher wrote:
There seems to be a second (dark) calibration at the beginning of each
strip, maybe with different integration times (Graeme mentioned
something like this when we met in Munich, but I can't remember the
details).
For reflective strip readings, that is the dark reference. It ensures
the same integration time, but I guess it also improves thermal tracking, and
may compensate somewhat for mechanical effects as well (ie. if the guide
spaces the instrument slightly from the media, the resulting light leakage
will get subtracted out.)
When I compare the dark current values obtained from the initial
calibration with the (assumed) dark readings at the beginning of the
strip (213...233), band 3 catches my eye as it seems to be an extreme
outlier (a "hot pixel"?) -- see
<http://digitalproof.info/argyll/eye-one_IR_calibration/offsets.pdf>
Hmm. Perhaps the sensors are only qualified over the official wavelength
range.
... but in the strip dark calibration, bands 1...4 get out of line:
<http://digitalproof.info/argyll/eye-one_IR_calibration/boxplot_strip_dark_cal.pdf>
More conformation that they shouldn't be used I think.
- my failed attempt to interpret the raw data correctly (10 bands out of
127, strip calibration removed):
<http://digitalproof.info/argyll/eye-one_IR_calibration/10_bands.pdf>
I'm not sure. All I can suggest is adding some printf's to output
the raw floating point values from within the driver.
Graeme Gill.
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