superpixel_bbox: Bounding box for the superpixel labels

In OpenImageR: An Image Processing Toolkit

Bounding box for the superpixel labels

Description

Bounding box for the superpixel labels

Usage

superpixel_bbox(superpixel_labels, non_overlapping_superpixels = FALSE)

Arguments

superpixel_labels	a matrix. The superpixel_labels parameter corresponds to the output labels of the superpixels function
non_overlapping_superpixels	either TRUE or FALSE. If TRUE then besides the (x,y) coordinates of each superpixel-segment (matrix), the overlapping indices for each superpixel will be returned (list). See the details section for more information

Details

If the non_overlapping_superpixels parameter is set to FALSE then : the superpixel_bbox function returns the bounding box for the labels of the superpixels function. The output is a matrix which contains the min and max indices of the x-y-coordinates and the corresponding unique superpixel labels.

If the non_overlapping_superpixels parameter is set to TRUE then : the superpixel_bbox function returns besides the previously explained matrix also the overlapping indices for each superpixel. These indices can be used to overwrite pixels with a specific value (say 0.0), which might appear in two superpixels simultaneously. This feature might be useful in case a user intends to use an algorithm and the separability of superpixel-segments is of importance.

Therefore in both cases overlapping superpixels will be computed, however if the non_overlapping_superpixels parameter is set to TRUE then also a list of overlapping indices will be returned.

Examples

library(OpenImageR)


#-----------
# read image
#-----------

path = system.file("tmp_images", "slic_im.png", package = "OpenImageR")

im = readImage(path)

im = im[,, 1:3]


#--------------------
# compute superpixels
#--------------------

res = superpixels(input_image = im, method = "slic", superpixel = 200,

                  compactness = 20, return_labels = TRUE)


#-------------------------
# compute the bounding box
#-------------------------

bbox = superpixel_bbox(res$labels, non_overlapping_superpixels = FALSE)


#-------------------------------------------
# plot the bounding boxes of the superpixels ( for illustration purposes )
#-------------------------------------------


graphics::plot(1:ncol(im), type='n', xlim = c(ncol(im), 1), ylim = c(1, nrow(im)))

graphics::rasterImage( flipImage(im), 1, 1, ncol(im), nrow(im))


for (i in 1:nrow(bbox)) {

  # the order of the bounding box is c('xmin', 'ymin', 'xmax', 'ymax')
  graphics::rect(bbox[i,3], bbox[i,1], bbox[i,4], bbox[i,2], border = "red", lwd = 2)
}

OpenImageR documentation built on July 9, 2023, 5:43 p.m.