Now Satisfied with the Rainbow colors for the noteheads.

[darkijah]

After some hours testing and printing out on my ink printer, this is the 
colors I have landed on for now. Adjusted and tuned and all.
All colors and notes should now be easy to distinguished :) Here is the 
whole file for now for colors, the colors can be seen by itself as there 
are some notes activated. They are usually turned off while including 
the script for whatever notesheet one is making for colors. So far so 
good :)

\version "2.22.1" \language "english" % Color
%{Jehovah's Rainbow to recall the destruction of the world wide flood,
Notes with Colors for Learners depending on Pitch or names,
Low to highest vibration: C=Red D=Orange E=Yellow F=Green G=Lightblue 
A=Blue B=Violet
the function used in this example even makes it possible to distinguish 
enharmonics.%}

%Association list of pitches to colors ♭C# ♭D# ♭E# ♭F# ♭G# ♭A# ♭B#:
#(define color-mapping(list
(cons (ly:make-pitch 0 0 FLAT) (rgb-color 1 0 0))
(cons (ly:make-pitch 0 0 NATURAL) (rgb-color 1 0 0))
(cons (ly:make-pitch 0 0 SHARP) (rgb-color 1 0 0))

(cons (ly:make-pitch 0 1 FLAT) (rgb-color 0.953 0.471 0.125))
(cons (ly:make-pitch 0 1 NATURAL) (rgb-color 0.953 0.471 0.125))
(cons (ly:make-pitch 0 1 SHARP) (rgb-color 0.953 0.471 0.125))

(cons (ly:make-pitch 0 2 FLAT) (rgb-color 1 0.804 0))
(cons (ly:make-pitch 0 2 NATURAL) (rgb-color 1 0.804 0))
(cons (ly:make-pitch 0 2 SHARP) (rgb-color 1 0.804 0))

(cons (ly:make-pitch 0 3 FLAT) (rgb-color 0 1 0))
(cons (ly:make-pitch 0 3 NATURAL) (rgb-color 0 1 0))
(cons (ly:make-pitch 0 3 SHARP) (rgb-color 0 1 0))

(cons (ly:make-pitch 0 4 FLAT) (rgb-color 0.298 0.855 0.988))
(cons (ly:make-pitch 0 4 NATURAL) (rgb-color 0.298 0.855 0.988))
(cons (ly:make-pitch 0 4 SHARP) (rgb-color 0.298 0.855 0.988))

(cons (ly:make-pitch 0 5 FLAT) (x11-color 'blue))
(cons (ly:make-pitch 0 5 NATURAL) (x11-color 'blue))
(cons (ly:make-pitch 0 5 SHARP) (x11-color 'blue))

(cons (ly:make-pitch 0 6 FLAT) (rgb-color 0.6 0 0.9))
(cons (ly:make-pitch 0 6 NATURAL) (rgb-color 0.6 0 0.9))
(cons (ly:make-pitch 0 6 SHARP) (rgb-color 0.6 0 0.9))))

%Compare pitch and alteration (not octave).
#(define (pitch-equals? p1 p2)(and
(= (ly:pitch-alteration p1) (ly:pitch-alteration p2))
(= (ly:pitch-notename p1) (ly:pitch-notename p2))))

#(define (pitch-to-color pitch)
(let ((color (assoc pitch color-mapping pitch-equals?)))(if color(cdr 
color))))

#(define (color-notehead grob)(pitch-to-color(ly:event-property 
(event-cause grob) 'pitch)))
% script end------------------------------------------------------

% (Rød-c red) (Orange-d orange) (Gul-e yellow3) (Grøn-f green4) (Blå-g 
blue) (Mørkeblå-a darkblue) (Violet-b violet)
% \override Beam.color = #(x11-color "medium turquoise")
% \override Accidental.color = #(rgb-color 1 0.3 0.3)
% \override NoteHead.color = #(rgb-color 0.5 0.5 0.5)
% \override Stem.color = #(rgb-color 0.8 0.8 0)
%instrument = \markup \with-color #green "Instrument"
% \markup { \with-color #red contain }

%Colors used From other note program where you had some few colors to 
choose from.
  %{Red%}       % #(rgb-color 0.898 0.098 0.141)
  %{Orange%}    % #(rgb-color 0.953 0.471 0.125)
  %{Yellow%}    % #(rgb-color 0.996 0.875 0)
  %{Green%}     % #(rgb-color 0 0.616 0.239)
  %{Teal%}      % #(rgb-color 0.298 0.855 0.988)
  %{Blue%}      % #(rgb-color 0.20 0.286 0.62)
  %{Violet%}    % #(rgb-color 0.694 0.325 0.62)

%{teal%} % #(rgb-color 0 0.502 0.502)

% (cons (ly:make-pitch 0 4 FLAT) (rgb-color 0.273 0.669 0.666))
%(cons (ly:make-pitch 0 4 NATURAL) (rgb-color 0.273 0.669 0.666))
%(cons (ly:make-pitch 0 4 SHARP) (rgb-color 0.273 0.669 0.666))




\layout { \context { \Staff
\remove "Time_signature_engraver"
\override TimeSignature #'stencil = #point-stencil }}

\score { \new Staff \relative d' { \cadenzaOn
\override NoteHead.color = #color-notehead \override NoteHead.font-size 
= #6
cf c cs df d ds ef e es ff f fs gf g gs af a as bf b bs cf c cs}}

\score { \new Staff \relative d' { \cadenzaOn \easyHeadsOn \override 
NoteHead.font-size = #6
\override NoteHead.color = #color-notehead
cf c cs df d ds ef e es ff f fs gf g gs af a as bf b bs cf c cs}}

\relative { \cadenzaOn \override NoteHead.color = #color-notehead  
\override NoteHead.font-size = #6
c d e f g a b c d e f g a b c d e f g a b c }

\relative { \cadenzaOn \override NoteHead.color = #color-notehead 
\easyHeadsOn \override NoteHead.font-size = #6
c d e f g a b c d e f g a b c d e f g a b c}


\score { \new Staff \relative d' { \cadenzaOn \easyHeadsOn \override 
NoteHead.font-size = #6
\override NoteHead.color = #color-notehead
d ds e es f fs g gs a as b bs c cs \bar "" \break d ds e es f fs g gs a 
as b bs c cs \bar "" \break d ds e es f fs g gs a as}}



\version "2.22.0"
lyricrevert= { \revert LyricText.color }
lyricRed = { \override LyricText.color = #red }

verse = \lyrics
{
      Black text \lyricRed Red Text \lyricrevert Black Text
}

\score {
  <<
    \new Staff \new Voice=tune \relative c'' { a4 a a a | a a2. }
    \lyricsto tune \verse
  >>
}