R/make_vignette_overlay.R

In rayimage: Image Processing for Simulated Cameras

#'@title Make Vignette Overlay
#'
#'@description Makes an overlay to simulate vignetting in a camera
#'
#'@param width Width of the image.
#'@param height Height of the image.
#'@param intensity Default `0.4`. `1` is max intensity, `0` is min.
#'@param radius Default `NULL`. Max of height or width, divided by 2.
#'@param radius_multiplier Default `1.3`.
#'@param color Default `black`.
#'@keywords internal
make_vignette_overlay = function(
  width,
  height,
  intensity = 0.3,
  radius_multiplier = 1.3,
  radius = NULL,
  color = "#000000"
) {
  value = array(
    0,
    dim = c(
      floor(width * radius_multiplier),
      floor(height * radius_multiplier),
      4
    )
  )
  hex_color = convert_color(color, as_hex = TRUE)
  color = convert_color(color)
  value[,, 4] = gen_ellipse(
    intensity,
    floor(width * radius_multiplier),
    floor(height * radius_multiplier)
  )
  value[,, 1] = color[1]
  value[,, 2] = color[2]
  value[,, 3] = color[3]

  tempcircle = tempfile(fileext = ".png")
  png::writePNG(value, tempcircle)
  imageval = magick::image_read(tempcircle)
  if (radius_multiplier >= 1) {
    imageval |>
      magick::image_blur(radius = radius / 2, sigma = radius / 4) |>
      magick::image_crop(sprintf(
        "%ix%i+%i+%i",
        height,
        width,
        floor((height * radius_multiplier - height) / 2),
        floor((width * radius_multiplier - width) / 2)
      )) |>
      magick::image_write(tempcircle)
  } else {
    imageval |>
      magick::image_border(
        geometry = sprintf(
          "%ix%i",
          (height - floor(height * radius_multiplier)) / 2,
          (width - floor(width * radius_multiplier)) / 2
        ),
        color = hex_color
      ) |>
      magick::image_blur(radius = radius / 2, sigma = radius / 4) |>
      magick::image_write(tempcircle)
  }
  return(tempcircle)
}