Segmentation of images based on Superpixels, Affinity propagation and Kmeans clustering

# init <- Image_Segmentation$new()

Details

sim_wL, sim_wA, sim_wB are the weights of the three channels. They keep balance so as to be consistent with human perception.

The quantity colorradius adjusts the number of clusters, and if its value is low, the number of targets would increase, which leads to more detailed segmentation results.

If the adjust_centroids_and_return_masks parameter is set to FALSE then the output kmeans_image_data will be an RGB image, otherwise it will be a black-and-white image.

colour_type parameter: RGB (Red-Green-Blue), LAB (Lightness, A-colour-dimension, B-colour-dimension) or HSV (Hue, Saturation, Value) colour.

Higher resolution images give better results.

The affinity propagation algorithm is used here with default parameter values.

By setting the sim_normalize parameter to TRUE, the affinity propagation algorithm requires less iterations to complete. However, the colorradius parameter does not have an effect if the similarity matrix is normalized.

Regarding the use_median parameter in the Rcpp I use the following steps: 1st. I compute the superpixels and extract the labels, 2nd. each superpixel label consists of multiple pixels and for these superpixels I have to compute a dissimilarity matrix therefore each superpixel must correspond to a single value, 3rd. to come to this single value for each superpixel the R user has the option to either use the 'mean' or the 'median of multiple image pixels (per superpixel)

---------------kmeans initializers----------------------

optimal_init : this initializer adds rows of the data incrementally, while checking that they do not already exist in the centroid-matrix

quantile_init : initialization of centroids by using the cummulative distance between observations and by removing potential duplicates

kmeans++ : kmeans++ initialization. Reference : http://theory.stanford.edu/~sergei/papers/kMeansPP-soda.pdf AND http://stackoverflow.com/questions/5466323/how-exactly-does-k-means-work

random : random selection of data rows as initial centroids

Methods

Image_Segmentation$new()
--------------
spixel_segmentation()
--------------
spixel_masks_show()
--------------
spixel_clusters_show()
--------------

References

https://www.ijsr.net/archive/v4i4/SUB152869.pdf , "Image Segmentation using SLIC Superpixels and Affinity Propagation Clustering", Bao Zhou, 2013, International Journal of Science and Research (IJSR)

Methods

Public methods

Image_Segmentation$new()
Image_Segmentation$spixel_segmentation()
Image_Segmentation$spixel_masks_show()
Image_Segmentation$spixel_clusters_show()
Image_Segmentation$clone()

Method `new()`

Usage

Image_Segmentation$new()

Method `spixel_segmentation()`

Usage

Image_Segmentation$spixel_segmentation(
  input_image,
  method = "slic",
  superpixel = 200,
  kmeans_method = "",
  AP_data = FALSE,
  use_median = TRUE,
  minib_kmeans_batch = 10,
  minib_kmeans_init_fraction = 0.5,
  kmeans_num_init = 3,
  kmeans_max_iters = 100,
  kmeans_initializer = "kmeans++",
  colour_type = "RGB",
  compactness_factor = 20,
  adjust_centroids_and_return_masks = FALSE,
  return_labels_2_dimensionsional = FALSE,
  sim_normalize = FALSE,
  sim_wL = 3,
  sim_wA = 10,
  sim_wB = 10,
  sim_color_radius = 20,
  ap_maxits = 1000,
  ap_convits = 100,
  ap_dampfact = 0.9,
  ap_nonoise = 0,
  verbose = FALSE
)

Arguments

input_image: a 3-dimensional input image (the range of the pixel values should be preferably in the range 0 to 255)
method: a character string specifying the superpixel method. It can be either "slic" or "slico"
superpixel: a numeric value specifying the number of superpixels
kmeans_method: a character string specifying the kmeans method. If not empty ("") then it can be either "kmeans" or "mini_batch_kmeans"
AP_data: a boolean. If TRUE then the affinity propagation image data will be computed and returned
use_median: a boolean. If TRUE then the median will be used rather than the mean value for the inner computations (see the details section for more information)
minib_kmeans_batch: the size of the mini batches
minib_kmeans_init_fraction: percentage of data to use for the initialization centroids (applies if initializer is kmeans++ or optimal_init). Should be a float number between 0.0 and 1.0.
kmeans_num_init: number of times the algorithm will be run with different centroid seeds
kmeans_max_iters: the maximum number of clustering iterations
kmeans_initializer: the method of initialization. One of, optimal_init, quantile_init, kmeans++ and random. See details for more information
colour_type: a character string specifying the colour type. It can be one of "RGB", "LAB" or "HSV"
compactness_factor: a numeric value specifying the compactness parameter in case that method is "slic"
adjust_centroids_and_return_masks: a boolean. If TRUE and the kmeans_method parameter is NOT empty ("") then the centroids will be adjusted and image-masks will be returned. This will allow me to plot the masks using the spixel_masks_show method.
return_labels_2_dimensionsional: a boolean. If TRUE then a matrix of labels based on the output superpixels in combination with the Affinity Propagation clusters will be returned
sim_normalize: a boolean. If TRUE then the constructed similarity matrix will be normalised to have unit p-norm (see the armadillo documentation for more details)
sim_wL: a numeric value specifying the weight for the "L" channel of the image (see the details section for more information)
sim_wA: a numeric value specifying the weight for the "A" channel of the image (see the details section for more information)
sim_wB: a numeric value specifying the weight for the "B" channel of the image (see the details section for more information)
sim_color_radius: a numeric value specifying the colorradius (see the details section for more information)
ap_maxits: a numeric value specifying the maximum number of iterations for the Affinity Propagation Clustering (defaults to 1000)
ap_convits: a numeric value. If the estimated exemplars stay fixed for convits iterations, the affinity propagation algorithm terminates early (defaults to 100)
ap_dampfact: a float number specifying the update equation damping level in [0.5, 1). Higher values correspond to heavy damping, which may be needed if oscillations occur in the Affinity Propagation Clustering (defaults to 0.9)
ap_nonoise: a float number. The affinity propagation algorithm adds a small amount of noise to data to prevent degenerate cases; this disables that.
verbose: a boolean. If TRUE then information will be printed in the console (spixel_masks_show method)

Method `spixel_masks_show()`

Usage

Image_Segmentation$spixel_masks_show(
  delay_display_seconds = 3,
  display_all = FALSE,
  margin_btw_plots = 0.15,
  verbose = FALSE
)

Arguments

delay_display_seconds: a numeric value specifying the seconds to delay the display of the next image (It displays the images consecutively). This parameter applies only if the display_all is set to FALSE (spixel_masks_show method)
display_all: a boolean. If TRUE then all images will be displayed in a grid (spixel_masks_show method)
margin_btw_plots: a float number specifying the margins between the plots if the display_all parameter is set to TRUE (spixel_masks_show method)
verbose: a boolean. If TRUE then information will be printed in the console (spixel_masks_show method)

Method `spixel_clusters_show()`

Usage

Image_Segmentation$spixel_clusters_show(
  spix_labels,
  color_palette = grDevices::rainbow,
  parameter_list_png = NULL
)

Arguments

spix_labels: a matrix. I can retrieve the "spix_labels" parameter by setting the "return_labels_2_dimensionsional" parameter to TRUE in the "spixel_segmentation" method (spixel_clusters_show method)
color_palette: one of the color palettes. Use ?grDevices::topo.colors to see the available color palettes
parameter_list_png: either NULL or a list of parameters passed to the ?grDevices::png function, such as list(filename = 'img.png', width = 100, height = 100, units = "px", pointsize = 12, bg = "white", type = "quartz")

Method `clone()`

The objects of this class are cloneable with this method.

Usage

Image_Segmentation$clone(deep = FALSE)

Arguments

deep: Whether to make a deep clone.

Examples


library(SuperpixelImageSegmentation)

path = system.file("images", "BSR_bsds500_image.jpg", package = "SuperpixelImageSegmentation")

im = OpenImageR::readImage(path)

init = Image_Segmentation$new()

num_spix = 10           # for illustration purposes
# num_spix = 600        # recommended number of superpixels

spx = init$spixel_segmentation(input_image = im,
                               superpixel = num_spix,
                               AP_data = TRUE,
                               use_median = TRUE,
                               return_labels_2_dimensionsional = TRUE,
                               sim_color_radius = 10)
#> Warning: The input data has values between 0.000000 and 1.000000. The image-data will be multiplied by the value: 255!


#...........................
# plot the superpixel labels
#...........................

plt = init$spixel_clusters_show(spix_labels = spx$spix_labels,
                                color_palette = grDevices::rainbow,
                                parameter_list_png = NULL)
#> Warning: device support for raster images unknown, ignoring 'raster=TRUE'

# plt


#....................................................
# create a binary image for a specified cluster label
#....................................................

pix_values = spx$spix_labels

target_cluster = 3                               # determine clusters visually ('plt' variable)

pix_values[pix_values != target_cluster] = 0     # set all other values to 0 (background)
pix_values[pix_values == target_cluster] = 1     # set the target_cluster to 1 (binary image)

# OpenImageR::imageShow(pix_values)

Segmentation of images based on Superpixels, Affinity propagation and Kmeans clustering

Details

Methods

References

Methods

Public methods

Method new()

Usage

Method spixel_segmentation()

Usage

Arguments

Method spixel_masks_show()

Usage

Arguments

Method spixel_clusters_show()

Usage

Arguments

Method clone()

Usage

Arguments

Examples

Method `new()`

Method `spixel_segmentation()`

Method `spixel_masks_show()`

Method `spixel_clusters_show()`

Method `clone()`