library(png)
library(plotwidgets)
#' Vibrance
#'
#' @param input_img string, path of the input .png image
#' @param intensity int, intensity of vibrance enhancement, between -10 and 10, defaults to 5
#' @param display bool, if TRUE, output will be displayed. Defaults to FALSE.
#' @param output_img string, path of the output .png image
#'
#' @return a png image at the specificed out path
#' @export
#'
#' @examples
#' \dontrun{
#' vibrance("./input.png", 5, FALSE, "./output.png")
#' }
vibrance <- function(input_img, intensity=5, display=F, output_img=""){
# argument validations
testit::assert("Please provide a valid string for the input image path.", is.character(input_img))
testit::assert("Please provide a valid string for the output image path.", is.character(output_img))
testit::assert("Please provide an intensity value between 0 and 10.", intensity <= 10 & intensity >= -10)
# load input image with exception handling
tryCatch(img <- png::readPNG(input_img),
error = function (e) {
stop("There is an error loading the image.")
})
# scale pixel values from [0, 1] back to [0, 255]
img <- img * 255
#getting dimensions
height <- dim(img)[1]
#transposed matrix array to get in order of RGB
t_matrix <- aperm(img, c(3,2,1))
#empty_array for output
enhanced_img <- array(dim = dim(img))
#2 linear loops needed for vectorizing & changing to HSL format instead if
for (i in (1:height)) {
t_matrix[,,i] <- plotwidgets::rgb2hsl(t_matrix[,,i])
}
# adjusting intensity
t_matrix[2,,] <- t_matrix[2,,] * (1 + (intensity)/10)
t_matrix[2,,] <- ifelse(t_matrix[2,,] > 1.0, 1.0, t_matrix[2,,])
# returnin
for (i in (1:height)) {
t_matrix[,,i] <- plotwidgets::hsl2rgb(t_matrix[,,i])
}
enhanced_img <- aperm(t_matrix, c(3, 2, 1))
enhanced_img <- enhanced_img / 255
# display or save enhanced image
if (display == TRUE) {
graphics::plot.new()
graphics::rasterImage(enhanced_img, 0, 0, 1, 1)
}
if (output_img != "") {
tryCatch(png::writePNG(enhanced_img, output_img),
error = function (e) {
stop("There is an error saving the image.")
})
}
}
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