Rvision (version 0.6.0)

simpleBlobDetector: Simple Blob Detector

Description

simpleBlobDetector implements a simple algorithm for extracting blobs an Image object. A blob is a region in an image that differs in properties (e.g. brightness, color) from surrounding regions.

Usage

simpleBlobDetector(
  image,
  min_threshold = 50,
  max_threshold = 220,
  threshold_step = 10,
  min_repeatability = 2,
  min_dist_between_blobs = 10,
  filter_by_area = TRUE,
  min_area = 25,
  max_area = 5000,
  filter_by_color = TRUE,
  blob_color = 0,
  filter_by_circularity = FALSE,
  min_circularity = 0.8,
  max_circularity = Inf,
  filter_by_convexity = TRUE,
  min_convexity = 0.95,
  max_convexity = Inf,
  filter_by_inertia = TRUE,
  min_inertia_ratio = 0.1,
  max_inertia_ratio = Inf
)

Arguments

image

An Image object.

min_threshold

A numeric value representing the starting thresholding value (see Note; default: 50).

max_threshold

A numeric value representing the ending thresholding value (see Note; default: 220).

threshold_step

A numeric value representing the step size to go from min_threshold to max_treshold (see Note; default: 10).

min_repeatability

A numeric value representing the number of threshold values a blob has to be detected at to be considered stable (see Note; default: 2).

min_dist_between_blobs

A numeric value representing the minimum distance in pixels between pixel group centers from several binary (thresholded) images above which they are considered as distinct blobs (default: 10).

filter_by_area

A logical indicating whether blobs should be filtered based on their area in pixels (default: TRUE).

min_area

A numeric value representing the smallest acceptable area for blobs (in pixels). Blobs smaller than this value are discarded (default: 25).

max_area

A numeric value representing the largest acceptable area for blobs (in pixels). Blobs larger than this value are discarded. (default: 5000).

filter_by_color

A logical indicating whether blobs should be filtered based on color (default: TRUE).

blob_color

An integer between 0 and 255 representing the color of the blobs. 0 will select dark blobs, 255 will select bright blobs (default: 0).

filter_by_circularity

A logical indicating whether blobs should be filtered based on circularity (default: FALSE).

min_circularity

A numeric value representing the smallest acceptable circularity for blobs. Blobs with smaller circularity than this value are discarded. (default: 0.8).

max_circularity

A numeric value representing the largest acceptable circularity for blobs. Blobs with larger circularity than this value are discarded. (default: Inf).

filter_by_convexity

A logical indicating whether blobs should be filtered based on convexity (default: TRUE).

min_convexity

A numeric value representing the smallest acceptable convexity for blobs. Blobs with smaller convexity than this value are discarded. (default: 0.95).

max_convexity

A numeric value representing the largest acceptable convexity for blobs. Blobs with larger convexity than this value are discarded. (default: Inf).

filter_by_inertia

A logical indicating whether blobs should be filtered based on their inertia ratio (default: TRUE).

min_inertia_ratio

A numeric value representing the smallest acceptable inertia ratio for blobs. Blobs with smaller ratio than this value are discarded. (default: 0.1).

max_inertia_ratio

A numeric value representing the largest acceptable inertia ratio for blobs. Blobs with larger ratio than this value are discarded. (default: Inf).

Value

A data frame of class blob with the following columns:

• "id":a unique identifier for each blob in the image.

• "x":the x coordinate of each blob in the image.

• "y":the y coordinate of each blob in the image.

• "size":the diameter of the circle containing the blob.

See Also

Image, isBlob

Examples

# NOT RUN {
dots <- image(system.file("sample_img/dots.jpg", package = "Rvision"))
blobs <- simpleBlobDetector(invert(dots), min_threshold = 25, max_threshold = 220,
                            filter_by_area = TRUE, min_area = 200, max_area = Inf,
                            filter_by_color = FALSE)

# }