Skip to contents

Optimized image resampling

Source: R/gg_annotation_raster.R
auto_image_resample.Rd

Downsample terra-based images for plotting. Uses window to set a virtual reading window on the image before calling spatSample, so only the relevant spatial ROI is read from disk. This avoids materializing a crop to disk for large ROIs while still focusing sampling on the plot region.

Usage

.auto_resample_gimage(
  img,
  plot_ext = NULL,
  img_border = 0.125,
  sample_fun = .sample_gimage,
  max_sample = getOption("giotto.plot_img_max_sample", 5e+05)
)

Arguments

img

giotto image to plot

plot_ext

extent of plot (defaults to the image extent)

img_border

numeric. Default = 0.125. If greater than 0, expand plot_ext by this fraction on each side before setting the window. See details.

max_sample

numeric. Default = 5e5. Maximum number of values to sample from the image. Globally settable with option "giotto.plot_img_max_sample"

Value

a giotto image resampled within the plot window

Details

img_border Expands the window extent used for reading the image. This prevents the image from being cut off sharply at the plot boundary, since plot extents are typically defined by centroids and polygons may hang over the edge.

See also

window, spatSample

Examples

if (FALSE) { # \dontrun{
img <- GiottoData::loadSubObjectMini("giottoLargeImage")
.auto_resample_gimage(img)
} # }