Leaves of Three Open Source Projects

appear identical. The only color spaces which produce \emph{different} 
interpolations are
\begin{itemize}
  \item RGB: because the interpolation is done in sRGB, not linear RGB.
  \item LAB: because LAB is a \emph{non-linear} transformation of XYZ.
  \item HSL/HSV: Because HSL/HSV are cylindrical/conical color spaces, using
  polar coordinates.
  \item OKLAB: Because, like LAB, it's a non-linear transformation of 
  XYZ.
  \item OKLCH: Because, like HSL/HSV, it's a cylindrical/conical color
  space that is \emph{also} derived from a non-linear transformation
  of XYZ (i.e., derived from OKLAB).
\end{itemize}

The same is true for color similarity (i.e., \texttt{color.dist()}): because
\texttt{xyz}, \texttt{yuv}, etc. are all linear transformations (matrix 
multiplications) of each other, their similarities will all be consistent.

\hypertarget{app-color-space-xyz}{%

\hypertarget{app-color-space-hsv}{%
\section{HSV}\label{aapp-color-space-hsv}}

\hypertarget{app-color-space-hsl}{%
\section{HSL}\label{aapp-color-space-hsl}}

\hypertarget{app-color-space-oklab}{%
\section{OKLAB}\label{aapp-color-space-oklab}}

\hypertarget{app-color-space-oklch}{%
\section{OKLCH}\label{aapp-color-space-oklch}}

\begin{prCode}
color.from('hsv', 180, 0.5, 0.5 );
color.from('yuv', 0.2, 0.5, 0.6 );
\end{prCode}

PR understands the color spaces \texttt{rgb} (\texttt{rgba} is an
alias), \texttt{hsv}, \texttt{hsl}, \texttt{xyz}, \texttt{lab},
\texttt{yuv}, and \texttt{yiq}, \texttt{ypbpr}, \texxtt{OKLAB} and 
\texttt{OKLCH} (the ``angular hue'' form of \texttt{OKLAB}). 
\texttt{from()} always returns colors with an alpha of 255. 

You can convert a sRGB color \emph{into} another color space, via 
\texttt{color.to}:
\begin{prCode}[emph={hue,sat,val}]
color.to('hsv', color`red`)  --->   [hue, sat, val]
\end{prCode}

pal.sort('order');
\end{prCode}

The sort order is optional and defaults to \texttt{"natural"}. The sort
order can be a comma-separated list of color components, e.g.,
\texttt{"r,g,b"} to mean, sort first by red, then by green, then by
blue. The color components must all come from the same color space, and
must match one of the color spaces PR knows about (RGB, HSV, HSL, etc.).


Alternatively, the sort order can be \texttt{"natural"} or
\texttt{"hilbert"}.

\begin{itemize}
\item
  In the \emph{natural} sort order, PR sorts the colors by Hue +

\texttt{xyz}     & CIE 1931 XYZ space               \\
\texttt{lab}     & CIELAB space, derived from XYZ (with D64 illuminant)  \\
\texttt{yib}     & YIB space, used by NTSC analog televisions \\
\texttt{yuv}     & YUV space, used by PAL analog televisions \\
\texttt{ypbpr}   & YPbPr space \\
\texttt{hsv}     & Hue-Saturation-Value space \\
\texttt{hsl}     & Hue-Saturation-Luma space \\
\texttt{oklab}   & OKLAB space \\
\texttt{oklch}   & OKLCH space, the ``polar form'' of OKLAB \\
\bottomrule
\end{tabulary}

See appendix \ref{app-color-space-definitions} for the full conversions 
to/from these color spaces.

Note that in \texttt{rgb} space, all components are integers in the range from