R: Add Overlay

add_image_overlay {rayimage} | R Documentation

## Add Overlay

### Description

Takes an RGB array/filename and adds an image overlay.

### Usage

    add_image_overlay(
      image,
      image_overlay = NULL,
      rescale_original = FALSE,
      alpha = NULL,
      filename = NULL,
      preview = FALSE
    )

### Arguments

`image` | Image filename or 3-layer RGB array.
`image_overlay` | Default `NULL`. Either a string indicating the location of a png image to overlay over the image (transparency included), or a 4-layer RGBA array. This image will be resized to the dimension of the image if it does not match exactly.
`rescale_original` | Default `FALSE`. If `TRUE`, function will resize the original image to match the overlay.
`alpha` | Default `NULL`, using overlay's alpha channel. Otherwise, this sets the alpha transparency by multiplying the existing alpha channel by this value (between 0 and 1).
`filename` | Default `NULL`. File to save the image to. If `NULL` and `preview = FALSE`, returns an RGB array.
`preview` | Default `FALSE`. If `TRUE`, it will display the image in addition to returning it.

### Value

3-layer RGB array of the processed image.

### Examples

    #Plot the dragon
    plot_image(dragon)

    #Add an overlay of a red semi-transparent circle:
    circlemat = generate_2d_disk(min(dim(dragon)[1:2]))
    circlemat = circlemat/max(circlemat)

    #Create RGBA image, with a transparency of 0.5
    rgba_array = array(1, dim=c(nrow(circlemat),ncol(circlemat),4))
    rgba_array[,,1] = circlemat
    rgba_array[,,2] = 0
    rgba_array[,,3] = 0
    dragon_clipped = dragon
    dragon_clipped[dragon_clipped > 1] = 1

    add_image_overlay(dragon_clipped, image_overlay = rgba_array,
                     alpha=0.5, preview = TRUE)

[Package rayimage version 0.5.1 Index]