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Fills a Connected Component with a Given Color.

Source: R/transform.R
floodFill.Rd

floodFill fills a connected component starting from a seed point with a specified color.

Usage

floodFill(
  image,
  seed = c(1, 1),
  color = "white",
  lo_diff = 0,
  up_diff = 0,
  connectivity = 4
)

Arguments

image

An Image object.

seed

A 2-element vector indicating the x and y coordinates of the seed point from where to start the filling.

color

A value or vector of any kind of R color specification compatible with col2bgr representing the color of the border (default: "white").

lo_diff

Maximal lower brightness/color difference between the currently observed pixel and one of its neighbors belonging to the component, or a seed pixel being added to the component (see Details). It can be a single value or a vector of the same length as the number n of channels in image. If it is shorter, its elements will be recycled. If it has more, only the first n elements will be used.

up_diff

Maximal upper brightness/color difference between the currently observed pixel and one of its neighbors belonging to the component, or a seed pixel being added to the component (see Details). It can be a single value or a vector of the same length as the number n of channels in image. If it is shorter, its elements will be recycled. If it has more, only the first n elements will be used.

connectivity

The connetivity neighborhood to decide whether 2 pixels are contiguous. This parameter can take two values:

  • 4: the neighborhood of a pixel are the four pixels located above (north), below (south), to the left (west) and right (east) of the pixel.

  • 8 (the default): the neighborhood of a pixel includes the four 4-neighbors and the four pixels along the diagonal directions (northeast, northwest, southeast, and southwest).

Value

This function returns the number of pixels that were filled and modifies image in place.

Details

The connectivity is determined by the color/brightness closeness of the neighbor pixels. The pixel at (x,y) is considered to belong to the repainted domain if:

  • in case of a floating range:

    • image[x',y'] - lo_diff <= image[x,y] <= image[x',y'] + up_diff

  • in case of a fixed range:

    • image[seed$x,seed$y] − lo_diff <= image[x,y] <= image(seed$x,seed$y) + up_diff

where image[x′,y′] is the value of one of pixel neighbors that is already known to belong to the component. That is, to be added to the connected component, a color/brightness of the pixel should be close enough to:

  • Color/brightness of one of its neighbors that already belong to the connected component in case of a floating range.

  • Color/brightness of the seed point in case of a fixed range.

See also

connectedComponents

Author

Simon Garnier, garnier@njit.edu

Examples

dots <- image(system.file("sample_img/dots.jpg", package = "Rvision"))
floodFill(dots, color = "green")
#> [1] 128564