Image Segmentation

Basic image segmentation like connected components labelling, blob extraction and fuzzy c-means

image_connect(image, connectivity = 4)

image_split(image, keep_color = TRUE)

image_fuzzycmeans(image, min_pixels = 1, smoothing = 1.5)

Arguments

image

magick image object returned by image_read() or image_graph()

connectivity

number neighbor colors which are considered part of a unique object

keep_color

if TRUE the output images retain the color of the input pixel. If FALSE all matching pixels are set black to retain only the image mask.

min_pixels

the minimum number of pixels contained in a hexahedra before it can be considered valid (expressed as a percentage)

smoothing

the smoothing threshold which eliminates noise in the second derivative of the histogram (higher values gives smoother second derivative)

Details

• image_connect Connect adjacent pixels with the same pixel intensities to do blob extraction

• image_split Splits the image according to pixel intensities

• image_fuzzycmeans Fuzzy c-means segmentation of the histogram of color components

image_connect performs blob extraction by scanning the image, pixel-by-pixel from top-left to bottom-right where regions of adjacent pixels which share the same set of intensity values get combined.

See also

Other image: _index_, analysis, animation, attributes(), color, composite, defines, device, edges, editing, effects(), fx, geometry, morphology, ocr, options(), painting, transform(), video

Examples

# Split an image by color
img <- image_quantize(logo, 4)
layers <- image_split(img)
layers
#> # A tibble: 4 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 PNG      640    480 sRGB       TRUE         0 72x72  
#> 2 PNG      640    480 sRGB       TRUE         0 72x72  
#> 3 PNG      640    480 sRGB       TRUE         0 72x72  
#> 4 PNG      640    480 sRGB       TRUE         0 72x72  

# This returns the original image
image_flatten(layers)
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 PNG      640    480 sRGB       TRUE         0 72x72  

# From the IM website
objects <- image_convert(demo_image("objects.gif"), colorspace = "Gray")
objects
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 GIF      256    171 Gray       FALSE        0 72x72  

# \donttest{
# Split image in blobs of connected pixel levels
if(magick_config()$version > "6.9.0"){
objects |>
  image_connect(connectivity = 4) |>
  image_split()

# Fuzzy c-means
image_fuzzycmeans(logo)

logo |>
  image_convert(colorspace = "HCL") |>
  image_fuzzycmeans(smoothing = 5)
}
#> # A tibble: 1 × 7
#>   format width height colorspace matte filesize density
#>   <chr>  <int>  <int> <chr>      <lgl>    <int> <chr>  
#> 1 GIF      640    480 HCL        FALSE        0 72x72  
# }