patch: Patch colour

In webmorphR: Reproducible Stimuli

Patch colour

Description

Get the median (or mean or user-defined function) colour value of a specified patch of pixels on an image. This is useful for matching background colours.

Usage

patch(
  stimuli,
  width = 10,
  height = 10,
  x_off = 0,
  y_off = 0,
  color = c("hex", "rgb"),
  func = stats::median
)

Arguments

stimuli	list of stimuli
width, height	dimensions of the patch in pixels, if <=1, interpreted as proportions of width or height
x_off, y_off	offset in pixels or proportion (<1)
color	The type of color to return (hex, rgb)
func	The function to apply to an array of L*ab color values to determine the central colour (defaults to median, but mean, min, or max can also be useful)

Details

The colour values of each pixel in the patch are converted to CIE-Lab values before using the func to calculate the central tendency of the L (lightness), a (red-green axis) and b (blue-yellow axis); see col2lab() and lab2rgb() for more details.

This excludes transparent pixels, and returns "transparent" if all pixels in the patch are transparent.

Value

a vector of hex or rgba color values

Examples

stimuli <- demo_stim()

# get colour from the upper left corder
patch(stimuli)

# get median colour from centre .1 width pixels
patch(stimuli, width = .1, height = .1, 
      x_off = .45, y_off = .45)

# get mean rgb colour from full image
patch(stimuli, width = 1, height = 1, 
      color = "rgb", func = mean)

webmorphR documentation built on June 2, 2022, 5:07 p.m.