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Thin Binary Image using Zhang-Suen Algorithm (Internal)

Source: R/Thinning4.R
thin_image_zhangsuen.Rd

This internal function performs image thinning using the Zhang-Suen thinning algorithm. It reduces binary images to their skeleton while preserving the structure and connectivity of the foreground pixels.

Usage

thin_image_zhangsuen(img, verbose = TRUE, select.layer = 2)

Arguments

img

A matrix, data frame, or `SpatRaster` object representing the binary image to be thinned.

verbose

Logical. If `TRUE`, prints diagnostic information such as iteration progress and pixel removal counts. Default is `TRUE`.

select.layer

Integer indicating the layer to use if `img` is a multi-layer `SpatRaster`. Default is 2.

Value

A binary matrix representing the thinned image (skeleton).

Details

- The function first prepares the image using the load_flexible_image function, ensuring binary matrix format. - Thinning is performed iteratively in two subiterations per cycle: 1. Identifying pixels to be removed based on Zhang-Suen conditions (first subiteration). 2. Refining removal decisions in the second subiteration. - The algorithm continues until no pixels are removed in an iteration or a maximum number of iterations is reached (default: 1000).

Examples

if (FALSE) { # \dontrun{
# Example usage
raster <- terra::rast(matrix(c(0, 1, 1, 0, 0, 1, 1, 0,0), nrow = 3))
thinned_image <- thin_image_zhangsuen(raster, verbose = TRUE, select.layer = NULL)
} # }