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Just really getting started on this ...

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gnuplot
octave

You might be able to install octave and gnuplot from your OS distribution. I used Ubuntu OS for this HOWTO, this also means the csv,txt,m and gnuplot files only have linefeeds and not carriage returns, use an appropriate text editor



A chromaticity diagram is a uniform two dimensional color gamut at a specific level of light. These calculations are at 100% light but any level from 0-1 can be used in the specific program as long as they are used consistently throughout the process.

XYZ tristimulus values can be found at http://cvrl.ioo.ucl.ac.uk/cmfs.htm

The CIE calculations and RGB color space primaries/calculations are from https://en.wikipedia.org/


Some basic concepts and planckian white point chromaticities from Olaf Schultz's o.schultz@enhydralutris.de awk work http://www.enhydralutris.de/Diverses/plotCIEwithGnuplot.tgz also found down further on my main page


You can download the all files from the following github to complete the HOWTO


Open a terminal, at the command prompt type octave and following these instructions


octave


octave:1>XYZ_to_xy;


Open another terminal, at the command prompt type the commands


gnuplot


gnuplot>load "visual_xy_locus.gnuplot"


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gnuplot>load "visual_xy_locus_and_line_of_purples.gnuplot"


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gnuplot>load "visual_xy_locus_and_line_of_purples_labels_planck.gnuplot"


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gnuplot>load "visual_xy_locus_and_line_of_purples_labels_planck_spaces.gnuplot"


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octave>XYZ = xy_to_XYZ_points(1);


octave>RGBlinear = XYZ_to_RGBlinear_points(XYZ);


octave>RGB = RGBlinear_to_RGB_points(RGBlinear);


octave>RGBintegers = RGB_to_RGBintegers_points(RGB);


octave>RGBhex = RGBintegers_to_RGBhex_points(RGBintegers);



gnuplot>load "visual_xy_locus_and_line_of_purples_labels_planck_spaces_sRGB_color.gnuplot"


The primary corners and neutral axes don't seem visually pure and aren't in gimp image editor, I'll do the reverse calculation from RGB to xy after this forward calculation plot


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The primary corners and neutral axes didn't seem visually pure and weren't in gimp image editor, here is the reverse calculations and plot, they look like they are supposed to, I don't know why the forward calculations don't, maybe I didn't adjust XYZ for white point before the forward calculations, you'll have to switch to the reverse_xy directory.


octave>makeRGB();


octave>RGB_to_rgb();


octave>rgb_to_rgbLinear();


octave>rgbLinear_to_XYZ();


octave>XYZ_to_xyz();


octave>xy_and_RGBhex();



gnuplot>load "reverse_xy_sRGB.gnuplot"


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