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

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
# 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