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Prepare an image

Source: R/utils_mapedit.R
image_prepare.Rd

This function aligns and crops the image using either base or mapview visualization. This is useful to prepare the images to be analyzed with analyze_objects_shp()

Usage

image_prepare(
  img,
  viewer = get_pliman_viewer(),
  downsample = NULL,
  max_pixels = 1e+06
)

Arguments

img

An optional Image object

viewer

The viewer option. If not provided, the value is retrieved using get_pliman_viewer(). This option controls the type of viewer to use for interactive plotting. The available options are "base" and "mapview". If set to "base", the base R graphics system is used for interactive plotting. If set to "mapview", the mapview package is used. To set this argument globally for all functions in the package, you can use the set_pliman_viewer() function. For example, you can run set_pliman_viewer("mapview") to set the viewer option to "mapview" for all functions.

downsample

integer; for each dimension the number of pixels/lines/bands etc that will be skipped; Defaults to NULL, which will find the best downsampling factor to approximate the max_pixels value.

max_pixels

integer > 0. Maximum number of cells to use for the plot. If max_pixels < npixels(img), regular sampling is used before plotting.

Value

The alighed/cropped image for further visualization or analysis.

Examples

# Example usage:
if (interactive() && requireNamespace("EBImage")) {
img <- image_pliman("mult_leaves.jpg")
image_prepare(img, viewer = "mapview")
}
#> Warning: GDAL Message 1: +init=epsg:XXXX syntax is deprecated. It might return a CRS with a non-EPSG compliant axis order.
#> Loading required namespace: leaflet.extras
#> Loading required package: shiny
#> 
#> Listening on http://127.0.0.1:6534
#> Error in UseMethod("st_transform"): no applicable method for 'st_transform' applied to an object of class "NULL"