qualpal 3.3.0
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Examples

Library Examples

Generate a palette from HSL color space.

#include <qualpal.h>
qualpal::Qualpal qp;
qp.setInputColorspace({ -170, 60 }, { 0, 0.7 }, { 0.2, 0.8 });
auto hsl_pal = qp.generate(5);
qualpal::Qualpal
Builder for qualitative color palette generation.
Definition qualpal.h:80
qualpal::Qualpal::generate
std::vector< colors::RGB > generate(std::size_t n)
Generate a qualitative color palette with the configured options.
qualpal::Qualpal::setInputColorspace
Qualpal & setInputColorspace(const std::array< double, 2 > &h_lim, const std::array< double, 2 > &s_or_c_lim, const std::array< double, 2 > &l_lim, ColorspaceType space=ColorspaceType::HSL)
Set input colors by sampling a colorspace (HSL or LCHab).
Five colors from the HSL color space

Select colors considering color vision deficiency:

qp.setInputPalette("ColorBrewer:Set2").setCvd({ { "deutan", 0.7 } });
auto cvd_pal = qp.generate(4);
qualpal::Qualpal::setInputPalette
Qualpal & setInputPalette(const std::string &palette_name)
Set input colors from a named palette.
qualpal::Qualpal::setCvd
Qualpal & setCvd(const std::map< std::string, double > &cvd_params)
Set color vision deficiency simulation parameters.
Four colors from ColorBrewer Set2 palette with deuteranomaly simulation

Here we design a CVD-friendly version of the "ColorBrewer:Set2" palette for a black background, selecting 3 colors.

qp.setInputPalette("ColorBrewer:Set2")
.setBackground(colors::RGB("#000000"))
.setCvd({ { "tritan", 0.2 }, { "deutan", 0.5 } })
.generate(3);
qualpal::Qualpal::setBackground
Qualpal & setBackground(const colors::RGB &bg_color)
Set the background color for palette generation.
Three colors from ColorBrewer Set2 palette with tritanomaly and deuteranomaly simulation on black background

Generate a palette from custom RGB colors:

qp.setInputRGB({
colors::RGB("#e41a1c"), // Red
colors::RGB("#377eb8"), // Blue
colors::RGB("#4daf4a"), // Green
colors::RGB("#984ea3"), // Purple
colors::RGB("#ff7f00"), // Orange
});
auto rgb_pal = qp.generate(3);
qualpal::Qualpal::setInputRGB
Qualpal & setInputRGB(const std::vector< colors::RGB > &colors)
Set input colors from a vector of RGB values.
Three colors from given RGB input

Generate a palette using a predefined palette:

qp.setInputPalette("Pokemon:Porygon");
auto palette = qp.generate(4);
Four colors from the Pokemon Porygon palette

Command Line Examples

Generate 5 colors from HSL color space:

qualpal -n 5 -i colorspace "-170:60" "0:0.7" "0.2:0.8"
Five colors from the HSL color space

Select 2 colors from hex values:

qualpal -n 2 "#ff0000" "#00ff00" "#0000ff"
Two colors from hex RGB input

Output palette as comma-delimited values:

qualpal -n 4 --output-delim comma "#ff0000" "#00ff00" "#0000ff" "#ffff00"
#ff0000,#0000ff,#00ff00,#ffff00

Analyze a palette for color difference:

qualpal analyze --input hex "#ff0000" "#00ff00" "#0000ff"
Color Difference Matrix (ciede2000 metric):
Colors analyzed: 3
Colors:
Idx      Hex  MinDist
    0  #ff0000    52.88
    1  #00ff00    83.19
    2  #0000ff    52.88

Color Difference Matrix:
        0       1       2
0     0.00   86.61   52.88
1    86.61    0.00   83.19
2    52.88   83.19    0.00

Generate palette for a dark background

qualpal -n 2 --background "#000000" "#e41a1c" "#377eb8" "#4daf4a" "#984ea3"
Two colors from given RGB input optimized for black background

Simulate color vision deficiency (CVD)

qualpal -n 4 --deutan 0.7 "#e41a1c" "#377eb8" "#4daf4a" "#984ea3"
Four colors from given RGB input with deuteranomaly simulation

Improve an existing palette and select subset

qualpal -n 3 -i palette "ColorBrewer:Set2" -b "#000000" --deutan 0.5 --tritan 0.2
Three colors from ColorBrewer Set2 palette with tritanomaly and deuteranomaly simulation on black background

A soothing pastel palette, generated from a HSL color space:

qualpal -n 5 -i colorspace "20:300" "0.3:0.7" "0.7:0.9"
A palette of pastels

Extend an existing palette:

qualpal -n 4 -i hex "#4daf4a" "#984ea3" "#ff7f00" "#ffff33" --extend "#e41a1c" "#377eb8"
A fixed palette of red and blue extended with four colors from given RGB input