R/render_resized.R

In rayimage: Image Processing for Simulated Cameras

#'@title Resize Image
#'
#'@description Resizes an image or a matrix, using bilinear interpolation.
#'
#'@param image Image filename, 3-layer RGB array, or matrix.
#'@param mag Default `1`. Amount to magnify the image, preserving aspect ratio. Overridden if
#'`dim` is not `NULL`.
#'@param dims Default `NULL`. Exact resized dimensions.
#'@param filename Default `NULL`. The filename of the image to be saved. If this is not given, the image will be plotted instead.
#'@param preview Default `FALSE`. Whether to plot the convolved image, or just to return the values.
#'@param method Default `trilinear`. Filters to up/downsample the image. Options: `bilinear`, `box`, `trilinear`,
#' `catmull`, `mitchell`.
#'@return 3-layer RGB resized array or matrix.
#'@export
#'@examples
#'if(run_documentation()){
#'#Plot the image with a title
#'dragon |>
#'  add_title("Dragon", title_offset=c(10,10), title_bar_color="black",
#'            title_size=20, title_color = "white") |>
#'  plot_image()
#'}
#'if(run_documentation()){
#'#Half of the resolution
#'render_resized(dragon, mag = 1/2) |>
#'  add_title("Dragon (half res)", title_offset=c(5,5), title_bar_color="black",
#'            title_size=10, title_color = "white") |>
#'  plot_image()
#'}
#'if(run_documentation()){
#'#Double the resolution
#'render_resized(dragon, mag = 2) |>
#'  add_title("Dragon (2x res)", title_offset=c(20,20), title_bar_color="black",
#'            title_size=40, title_color = "white") |>
#'  plot_image()
#'}
#'if(run_documentation()){
#'#Specify the exact resulting dimensions
#'render_resized(dragon, dim = c(320,160)) |>
#'  add_title("Dragon (custom size)", title_offset=c(10,10), title_bar_color="black",
#'            title_size=20, title_color = "white") |>
#'  plot_image()
#'}
render_resized = function(image, mag = 1, dims = NULL, filename=NULL, preview=FALSE,
                          method = "tri") {
  if(!is.null(filename)) {
    if(tools::file_ext(filename) != "png") {
      filename = paste0(filename,".png")
    }
  }
  imagetype = get_file_type(image)
  temp_image = ray_read_image(image)

  if(method %in% c("bi","bilinear")) {
    if(!is.null(dims)) {
      dims = dims[1:2]/dim(temp_image)[1:2]
    }
    temp_list = list()
    if(imagetype != "matrix") {
      for(i in 1:3) {
        if(is.null(dims)) {
          temp_list[[i]] = resize_image(temp_image[,,i], mag)
        } else {
          x1 = seq(1, nrow(temp_image), length.out = nrow(temp_image)*dims[1]);
          y1 = seq(1, ncol(temp_image), length.out = ncol(temp_image)*dims[2]);
          temp_list[[i]] = resize_image_xy(temp_image[,,i], x1, y1)
        }
      }
      temp_image = array(0, dim = c(nrow(temp_list[[1]]), ncol(temp_list[[1]]), 3))
      temp_image[,,1] = temp_list[[1]]
      temp_image[,,2] = temp_list[[2]]
      temp_image[,,3] = temp_list[[3]]
    } else {
      if(is.null(dims)) {
        temp_image = resize_image(t(flipud(temp_image)), mag)
      } else {
        x1 = seq(1, nrow(temp_image), length.out = nrow(temp_image)*dims[1]);
        y1 = seq(1, ncol(temp_image), length.out = ncol(temp_image)*dims[2]);
        temp_image = resize_image_xy(t(flipud(temp_image)), x1, y1)
      }
    }
  } else {
    method = tolower(method)
    method = switch(method, "default" = 0, "box" = 1,"triangle" = 2, "tri" = 3,
                    "trilinear" = 3,"cubic" = 3, "catmull" = 4,"mitchell" = 5, 3)
    if(is.null(dims)) {
      dims = mag*dim(image)[1:2]
    }
    temp_list = list()
    if(imagetype != "matrix") {
      for(i in 1:(dim(image)[3])) {
        temp_list[[i]] = resize_matrix_stb(temp_image[,,i], dims[1],dims[2],method)
      }
      temp_image = array(0, dim = c(dims[1], dims[2], dim(image)[3]))
      for(i in 1:(dim(image)[3])) {
        temp_image[,,i] = temp_list[[i]]
      }
    } else {
      temp_image = resize_matrix_stb(temp_image, dims[1],dims[2],method)
    }
  }
  if(is.null(filename)) {
    if(preview) {
      plot_image(render_clamp(temp_image))
      return(invisible(temp_image))
    } else {
      temp_image
    }
  } else {
    ray_write_image(render_clamp(temp_image),filename)
  }
}