pastel random -n 20 | pastel sort --by luminance
pastel list | pastel sort --by chroma

Also, add a --reverse/-r flag.

Think about whether we still need the --sort option on pastel list.

Which computes contrast, color difference, etc.

in the interactive version, we could show a-colored text on a b-colored background. Also, show two color panels (like in pastel color) directly next to each other.

To print the color in rgb(…), hsl(…), #rrggbb etc format

• hue, chroma, luminance
• LCh
• Lab
• name - format as closest matching X11 name

e.g.:

pastel random -n 1000000 | pastel format hex

e.g.: print #RRGGBB with red, green, and blue components

We distinguish 3 modes:

• no color
• 8 bit mode (\x1b[38;5;167m)
• 24 bit mode, aka "true color" (\x1b[38;2;255;0;127m)

Note that we ignore the 16-color ANSI mode, as we can't really predict how the 16 colors look like.

We choose the mode in the following way:

• If --mode=24bit or --mode=8bit => use the given mode.
• Otherwise, if the output goes to a non-interactive terminal => use no color mode
• Otherwise, if PASTEL_MODE=8bit, use 8 bit mode
• Otherwise, if PASTEL_MODE==24bit or COLORTERM==truecolor or COLORTERM==24bit => use 24 bit mode
• Otherwise, use 8 bit mode and show a warning.

Further literature: https://gist.github.com/XVilka/8346728

• do we have to include the code to enable ANSI codes on Windows? This does not seem to be required on Windows 10?
• Make sure that we don't show the "COLORTERM" warning. PowerShell is not going to set this for us.
• pastel pick => any supported tools?

In non-interactive mode, pastel should simply print the color as #rrggbb string in order to allow for things like this:

echo salmon | pastel darken 0.2 | pastel saturate 0.1

pastel darken 0.1 red | pastel mix RGB green | pastel saturate 0.1

• input
• output

For example

pastel random | pastel set luminance 0.4

we could even think about replacing saturate, lighten, etc. with:

pastel modify saturation +0.3
pastel set saturation 0.5
...

… otherwise, this does not work:

pastel show blue | pastel desaturate 1.0 | pastel saturate 1.0

our current choice for orangered #ff4500 is not great :-/

Basically like a "reactive" web page: choose a smaller output width if the terminal width is too small to display the full canvas width.

.. this should work even if we are in interactive mode.

To do things like:

pastel darken 0.2 red

# okay, let's compare it to the original color:
pastel darken 0.2 red | pastel show red -

Check other sources for more "named" colors:

• CamelCase variants of named colors? SandyBrown? https://www.youtube.com/watch?v=HmStJQzclHc
• consistently use both "gray" and "grey"
• Matplotlib color "names": 'b', 'g', 'r', 'c', 'm', 'y', 'k', 'w'
• https://xkcd.com/color/rgb/
• https://github.com/tajmone/name-that-color#colors-names

e.g.:

pastel list | pastel sortby luminance | head -n20 | pastel darken 0.2
pastel random 20 | pastel show

Provide a way to:

• Show the 24-bit ANSI code for a given color
• Show an approximated 8-bit ANSI code for a given color
• (Show the best-matching ansi16 color)

Use cases:

pastel paint red "ERROR: ..."
pastel paint red --bold "ERROR: ..."
pastel paint black --on yellow "WARNING: ..."

pastel red | pastel lighten 0.2 | pastel paint - "ERROR: ..."

echo "$(pastel ansi salmon)colored text$(pastel ansi reset)"

Reading input is currently really slow:

▶ pastel random -n 1000 > colors
▶ hyperfine 'pastel format hex < colors'
Benchmark #1: pastel format hex < colors
  Time (mean ± σ):     313.8 ms ±   5.9 ms    [User: 309.8 ms, System: 3.5 ms]
  Range (min … max):   307.8 ms … 327.9 ms    10 runs

The main reason is that we compile the regexes in each iteration:

Using the similar_colors function.

There are many ways to generate random colors. Sampling uniformly in RGB space is probably not very interesting as it will likely produce a lot of dull, grayish and brownish colors.

Sampling in HSL space with a restricted range on saturation and lightness could be more interesting if we are interested in more vivid colors.

Using Lab or LCH space could be even better because we are now sampling "correctly" with respect to perceived color distances.

We could probably add an argument to the pastel random command for the sampling strategy.

Actual use cases:

• Convert colors to a different format (pastel format hsl ff8000)
• Quickly preview a given color (pastel color "rgb(255,50,127)")
• Pick a color from a palette, show it in all kinds of different formats (pastel pick)
• Pick a color somewhere from the screen (pastel pick)
• Use pastel paint to print colorized text from shell scripts (with automatic mode detection) ==> actually try this (how to switch off colors?)!
• Generate a distinct colors for a plot/map/... (pastel distinct -n 5)
• Generate a gradient of colors (pastel gradient pick pick | pastel format hex)
• Sample from a predefined color scale (pastel sample magma 0.3)

Some ideas for cool demos / snippets:

(see https://www.colourlovers.com/colors/most-loved/all-time/meta for some cool colors 😄)

# basics
pastel show 0077ff
# https://www.colourlovers.com/palette/1930/cheer_up_emo_kid
pastel color 556270 4ecdc4 c7f484 ff6b6b c44d58


pastel show salmon
pastel show salmon | pastel darken 0.2
pastel show salmon | pastel darken 0.2 | pastel desaturate 0.5

my_color=$(pastel show salmon | pastel darken 0.2 | pastel desaturate 0.5)

pastel show red blue green

pastel random
pastel random | pastel format
pastel random -n 30 | pastel sort-by hue | pastel format
pastel random -n 100 -s lch_hue | pastel sort-by hue | \
  xargs -L1 -I{} pastel paint black --on "{}" "        "

pastel random -s gray | pastel mix cyan | pastel format

(pastel gradient ffffcc fd8d3c;
 pastel gradient fd8d3c 800026) | \
  xargs -L1 -I{} pastel paint black --on "{}" "  " -n
echo


pastel gradient -n 20 -s hsl pick pick  | pastel format hex


bg="hotpink"
fg="$(pastel textcolor "$bg")"

pastel paint "$fg" --on "$bg" "well readable text"

Integration with other Unix tools:

• seq:

  LANG=en seq 0 0.04 1 | sed -e 's/^/gray(/' -e 's/$/)/' | pastel format hex

• xargs, xargs -L1
• head, tail
• sed
• sort

Other points:

• Warning about supported terminals (truecolor & unicode)

Literature:

• https://ciechanow.ski/color-spaces/
• https://en.wikipedia.org/wiki/Line_of_purples
• https://en.wikipedia.org/wiki/Impossible_color
• https://en.wikipedia.org/wiki/SRGB
• https://en.wikipedia.org/wiki/Lab_color_space
• https://www.youtube.com/watch?v=HmStJQzclHc
• https://www.w3.org/TR/SVG11/types.html#ColorKeywords

pastel paint -n black --on red --bold "   ERROR!   "
echo " A serious error"

pastel paint -n black --on yellow --bold "  WARNING!  "
echo " A warning message"

pastel paint -n black --on limegreen --bold "    INFO    "
echo -n " Informational message with a "
echo -n "highlighted" | pastel paint -n default --underline
echo " word"

... to force color output (e.g. -f/--force-color).

• input
• output

see

pastel random -s uniform_rgb -n $(insect '255*255*255') | pastel format hex | grep 000000

See https://developer.mozilla.org/en-US/docs/Web/CSS/color_value for all details and test cases

• hexadecimal RRGGBB (#ff0000)
• hexadecimal RGB (#f00)
• rgb(0, 0, 255)
• rgb(0%, 50%, 100%)
• hsl(120, 100%, 75%)
• hsl(…,…,…) in all variations
  • With and without ° sign
  • Negative angles
• predefined color names
• CSS Level 4 predefined names (rebeccapurple)

optional:

• CSS Color Level 4: space-separated rgb(R G B[ A]) - only a draft
• gray(0.3)
• gray(30%)
• rad instead of degrees
• turns instead of degrees