mapToColors: Map intensity values to colors

In neuroim2: Data Structures for Brain Imaging Data

Map intensity values to colors

Description

Convert intensity values (e.g., a 2D slice) into a color representation for plotting and overlays.

Usage

mapToColors(
  imslice,
  col = heat.colors(128, alpha = 1),
  zero_col = "#00000000",
  alpha = 1,
  irange = range(imslice),
  threshold = c(0, 0)
)

Arguments

imslice	A numeric vector or array of intensities.
col	A vector of colors used as a lookup table.
zero_col	Color used for exactly-zero intensities (defaults to transparent).
alpha	Global alpha multiplier applied to all colors when alpha < 1.
irange	Intensity range used to normalize values before mapping to col.
threshold	Optional length-2 numeric vector. If diff(threshold) > 0, values within [threshold[1], threshold[2]] are set to transparent.

Value

If alpha == 1, returns a character vector/array of colors. If alpha < 1, returns an array with an added RGBA channel (last dimension length 4).

neuroim2 documentation built on April 16, 2026, 5:07 p.m.