Crop Image

Crops an image (or matrix) either by specifying axis-aligned limits (width_limits/height_limits) or by specifying a centered box size via center.

render_crop(
  image = NULL,
  width_limits = NULL,
  height_limits = NULL,
  center = NULL,
  filename = NULL,
  preview = FALSE
)

Arguments

image

Default NULL. 3-layer RGB/4-layer RGBA array, rayimg class, or filename of an image.

width_limits

Default NULL. Length-2 numeric (xmin, xmax) along the width (x/columns). Values in [0,1] are treated as fractions of image width; otherwise they are pixel indices. Mutually exclusive with center. If provided alone, height_limits defaults to full height.

height_limits

Default NULL. Length-2 numeric (ymin, ymax) along the height (y/rows). Values in [0,1] are treated as fractions of image height; otherwise they are pixel indices. Mutually exclusive with center. If provided alone, width_limits defaults to full width.

center

Default NULL. Length-2 numeric (height, width) for a center-crop. Values in (0,1] are treated as fractions of (image height, image width); otherwise pixels. Mutually exclusive with width_limits/height_limits.

filename

Default NULL. The filename of the image to be saved. If this is not given, the image will be plotted instead.

preview

Default FALSE. Whether to plot the cropped image, or just to return the values.

Value

A rayimg array with the cropped region.

Examples

# Left half of the image
if(run_documentation()){
render_crop(dragon,
           width_limits = c(0, 0.50),
           height_limits = c(0, 1)) |>
 plot_image()
}

# Right half of the image
if(run_documentation()){
render_crop(dragon,
           width_limits = c(0.50, 1),
           height_limits = c(0, 1)) |>
 plot_image()
}

# Top middle of the image (25%–50% height, 25%–75% width)
if(run_documentation()){
render_crop(dragon,
           height_limits = c(0.25, 0.50),
           width_limits  = c(0.25, 0.75)) |>
 plot_image()
}

# Top middle, explicit pixel coords (for a 200x200 image)
if(run_documentation()){
render_crop(dragon,
           height_limits = c(50, 100),
           width_limits  = c(50, 150)) |>
 plot_image()
}

# Center-crop: 50% height and width of the image
if(run_documentation()){
render_crop(dragon, center = c(0.5, 0.5)) |>
 plot_image()
}

# Center-crop: fixed 50x100 pixels
if(run_documentation()){
render_crop(dragon, center = c(50, 100)) |>
 plot_image()
}