vol.intensity.to.color: Convert integer intensity image to RGB color string form.

In fsbrain: Managing and Visualizing Brain Surface Data

Convert integer intensity image to RGB color string form.

Description

Convert a gray-scale image defined by intensity values in range ⁠[0, 1]⁠ to an image with identical dimensions that contains an R color string (like ⁠#222222⁠) at each position. The color strings are computed from the intensities, by taking the intensity value as the value for all three RGB channels. I.e., the output is still gray-scale, but defined in RGB space. To make it clear, this function does not apply a colormap. It only changes the representation of the data, not the resulting colors.

Usage

vol.intensity.to.color(volume, scale = NULL)

Arguments

volume

numeric array, typically a 3D image with intensities in range ⁠[0, 1]⁠. This function now also supports numeric matrices (2D images, slices) and numeric vectors (1D).

scale

numeric or character string, a scaling to apply to the values. Defaults to NULL, which means no scaling and requires the values in volume to be in rage ⁠[0, 1]⁠. You can pass a number like 255 or the string 'normalize' to scale based on the data. You can pass the string 'normalize_if_needed' to scale only if the data is outside the range ⁠[0, 1]⁠, so that data in range ⁠[0.3, 0.5]⁠ would not be rescaled to ⁠[0, 1]⁠.

Value

array (or matrix, or vector) of RGB color strings. All of them will represent gray values.

Examples

   vol.intensity.to.color(c(0.0, 0.5, 1.0));
   # output: "#000000" "#808080" "#FFFFFF"
   vol.intensity.to.color(c(20, 186, 240), scale="normalize");
   vol.intensity.to.color(c(20, 186, 240), scale=255);
   vol.intensity.to.color(c(0.0, 0.5, 0.8), scale="normalize");
   vol.intensity.to.color(c(0.0, 0.5, 0.8), scale="normalize_if_needed");

fsbrain documentation built on Aug. 23, 2026, 5:06 p.m.