% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/render_alpha_outline.R
\name{composite_alpha_outline_image}
\alias{composite_alpha_outline_image}
\title{Composite Alpha Outline Image}
\usage{
composite_alpha_outline_image(halo_image, source_image)
}
\arguments{
\item{halo_image}{RGBA outline image used as the compositing backdrop.}

\item{source_image}{RGBA source image, padded to the same dimensions as
\code{halo_image}, used as the compositing foreground.}
}
\value{
A \code{rayimg} RGBA image containing the source composited over the
outline.
}
\description{
Internal helper that composites the original source image over
the generated outline using source-over alpha compositing. The outline is the
backdrop and the source image is the foreground. Colors are treated as
straight, non-premultiplied alpha, using
\code{Ao = Af + Ab * (1 - Af)} and
\code{Co = (Cf * Af + Cb * Ab * (1 - Af)) / Ao}. Fully transparent output pixels
are forced to black to avoid carrying arbitrary color values.
}
\keyword{internal}
