rasterpic

rasterpic is a tiny package with a single goal: to transform an image into a terra SpatRaster object (see ?terra::SpatRaster).

Installation

Check the documentation for the development version at https://dieghernan.github.io/rasterpic/dev/.

You can install the development version of rasterpic with:

# install.packages("pak")
pak::pak("dieghernan/rasterpic")

Alternatively, you can install rasterpic using the r-universe:

# Install rasterpic in R.
install.packages(
  "rasterpic",
  repos = c(
    "https://dieghernan.r-universe.dev",
    "https://cloud.r-project.org"
  )
)

Example

You can create custom maps with several spatial input classes:

• sf classes: sf, sfc, sfg or bbox.
• terra classes: SpatRaster, SpatVector and SpatExtent.
• stars classes: stars.
• A numeric coordinate vector of the form c(xmin, ymin, xmax, ymax).

The main function, rasterpic_img(), is an S3 generic. The methods for extent-like inputs use the object extent, and vector methods can also mask the image to the object shape.

An example using an sf object:

library(rasterpic)
library(sf)
library(terra)

# Use the flag of the United Kingdom.
img <- system.file("img/UK_flag.png", package = "rasterpic")
uk <- read_sf(system.file("gpkg/UK.gpkg", package = "rasterpic"))

class(uk)
#> [1] "sf"         "tbl_df"     "tbl"        "data.frame"

# Rasterize the image.
uk_flag <- rasterpic_img(uk, img)

uk_flag
#> class       : SpatRaster
#> size        : 400, 800, 3  (nrow, ncol, nlyr)
#> resolution  : 5398.319, 5398.319  (x, y)
#> extent      : -2542183, 1776472, 6430573, 8589900  (xmin, xmax, ymin, ymax)
#> coord. ref. : WGS 84 / Pseudo-Mercator (EPSG:3857)
#> source(s)   : memory
#> colors rgb  : 1, 2, 3
#> names       :   r,   g,   b
#> min values  :   0,  14,  35
#> max values  : 255, 255, 255

# Plot with ggplot2 and tidyterra.
library(tidyterra)
library(ggplot2)

autoplot(uk_flag) +
  geom_sf(data = uk, color = alpha("blue", 0.5))

We can also adjust other parameters and modify the alignment of the image with respect to the object:

# Align, crop and mask.
uk_flag2 <- rasterpic_img(uk, img, halign = 0.2, crop = TRUE, mask = TRUE)

autoplot(uk_flag2) +
  geom_sf(data = uk, fill = NA)

Supported image formats

rasterpic can parse the following image formats:

• png files.
• jpeg/jpg files.
• tiff/tif files.

Citation

Hernangómez D (2026). rasterpic: Convert Digital Images to SpatRaster Objects. doi:10.32614/CRAN.package.rasterpic. https://dieghernan.github.io/rasterpic/.

A BibTeX entry for LaTeX users is:

@Manual{R-rasterpic,
  title = {{rasterpic}: Convert Digital Images to {SpatRaster} Objects},
  doi = {10.32614/CRAN.package.rasterpic},
  author = {Diego Hernangómez},
  year = {2026},
  version = {0.4.0.9000},
  url = {https://dieghernan.github.io/rasterpic/},
  abstract = {Create SpatRaster objects, as defined by the terra package, from digital images using a spatial object as a geographic reference. Supported inputs include objects from the sf, terra and stars packages. The main function is an S3 generic, so other packages can provide methods for additional spatial classes.},
}