Discussion:
Anyone know where to find a cie/it8 file for the Color Checker Passport?
(too old to reply)
Robert Bieber
2018-02-28 03:46:26 UTC
Permalink
I'm curious if anyone's had any luck building a profile with dt-chart
using a cie/it8 file for the second step in the process. I've gotten it
to work successfully by using the chart file that ships with Argyll, but
if I try to use the corresponding cie file for the next step, I get an
error message "error with the IT8 file, can't find the SAMPLE_ID column."

I'm guessing that even though the option says cie/it8 file, maybe only
it8 files are well supported?  Or maybe the one that Argyll ships with
is just malformed.  Does anyone have an idea where I might find a usable
it8 file for the ColorChecker passport?  This seems like something that
should be prominently published by the manufacturer, but the only place
I was able to find cht and cie files at all was in the Argyll distribution

Thanks,
Robby
Tobias Ellinghaus
2018-02-28 10:12:57 UTC
Permalink
Post by Robert Bieber
I'm curious if anyone's had any luck building a profile with dt-chart
using a cie/it8 file for the second step in the process. I've gotten it
to work successfully by using the chart file that ships with Argyll, but
if I try to use the corresponding cie file for the next step, I get an
error message "error with the IT8 file, can't find the SAMPLE_ID column."
I'm guessing that even though the option says cie/it8 file, maybe only
it8 files are well supported? Or maybe the one that Argyll ships with
is just malformed. Does anyone have an idea where I might find a usable
it8 file for the ColorChecker passport? This seems like something that
should be prominently published by the manufacturer, but the only place
I was able to find cht and cie files at all was in the Argyll distribution
The file ColorCheckerPassport.cie as shipped by Argyll uses "SAMPLE_LOC"
instead of "SAMPLE_ID" to refer to the colors. Just changing the line

SAMPLE_LOC XYZ_X XYZ_Y XYZ_Z LAB_L LAB_A LAB_B

to

SAMPLE_ID XYZ_X XYZ_Y XYZ_Z LAB_L LAB_A LAB_B

made it work for me. At least darktable-chart no longer complained. That being
said, the Lab values dt-chart computes from the XYZ reference numbers look off
to me. I'll have a look.
Post by Robert Bieber
Thanks,
Robby
Tobias
Tobias Ellinghaus
2018-02-28 10:53:22 UTC
Permalink
Post by Tobias Ellinghaus
Post by Robert Bieber
I'm curious if anyone's had any luck building a profile with dt-chart
using a cie/it8 file for the second step in the process. I've gotten it
to work successfully by using the chart file that ships with Argyll, but
if I try to use the corresponding cie file for the next step, I get an
error message "error with the IT8 file, can't find the SAMPLE_ID column."
I'm guessing that even though the option says cie/it8 file, maybe only
it8 files are well supported? Or maybe the one that Argyll ships with
is just malformed. Does anyone have an idea where I might find a usable
it8 file for the ColorChecker passport? This seems like something that
should be prominently published by the manufacturer, but the only place
I was able to find cht and cie files at all was in the Argyll distribution
The file ColorCheckerPassport.cie as shipped by Argyll uses "SAMPLE_LOC"
instead of "SAMPLE_ID" to refer to the colors. Just changing the line
SAMPLE_LOC XYZ_X XYZ_Y XYZ_Z LAB_L LAB_A LAB_B
to
SAMPLE_ID XYZ_X XYZ_Y XYZ_Z LAB_L LAB_A LAB_B
made it work for me. At least darktable-chart no longer complained. That
being said, the Lab values dt-chart computes from the XYZ reference numbers
look off to me. I'll have a look.
I had a look. It seems that lcms2 fails to properly parse float numbers when
the current locale uses anything else than '.' as the decimal separator. So
please make sure to run dt-chart with LANG=C. :-(
Post by Tobias Ellinghaus
Post by Robert Bieber
Thanks,
Robby
Tobias
Robert Bieber
2018-02-28 23:45:02 UTC
Permalink
That did it, thanks!
Post by Tobias Ellinghaus
Post by Tobias Ellinghaus
Post by Robert Bieber
I'm curious if anyone's had any luck building a profile with dt-chart
using a cie/it8 file for the second step in the process. I've gotten it
to work successfully by using the chart file that ships with Argyll, but
if I try to use the corresponding cie file for the next step, I get an
error message "error with the IT8 file, can't find the SAMPLE_ID column."
I'm guessing that even though the option says cie/it8 file, maybe only
it8 files are well supported? Or maybe the one that Argyll ships with
is just malformed. Does anyone have an idea where I might find a usable
it8 file for the ColorChecker passport? This seems like something that
should be prominently published by the manufacturer, but the only place
I was able to find cht and cie files at all was in the Argyll distribution
The file ColorCheckerPassport.cie as shipped by Argyll uses "SAMPLE_LOC"
instead of "SAMPLE_ID" to refer to the colors. Just changing the line
SAMPLE_LOC XYZ_X XYZ_Y XYZ_Z LAB_L LAB_A LAB_B
to
SAMPLE_ID XYZ_X XYZ_Y XYZ_Z LAB_L LAB_A LAB_B
made it work for me. At least darktable-chart no longer complained. That
being said, the Lab values dt-chart computes from the XYZ reference numbers
look off to me. I'll have a look.
I had a look. It seems that lcms2 fails to properly parse float numbers when
the current locale uses anything else than '.' as the decimal separator. So
please make sure to run dt-chart with LANG=C. :-(
Post by Tobias Ellinghaus
Post by Robert Bieber
Thanks,
Robby
Tobias
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