Applies the Sobel-Feldman Operator to detect edges. The operator is based on convolving the image with a small, separable, and integer-valued filter in the horizontal and vertical directions.
Arguments
- img
An image or a list of images of class
Image.- sigma
Gaussian kernel standard deviation used in the gaussian blur.
- threshold
The theshold method to be used. If
threshold = "Otsu"(default), a threshold value based on Otsu's method is used to reduce the grayscale image to a binary image. If any non-numeric value different than"Otsu"is used, an iterative section will allow you to choose the threshold based on a raster plot showing pixel intensity of the index. Alternatively, provide a numeric value to be used as the threshold value.- thinning
Logical value indicating whether a thinning procedure should be applied to the detected edges. See
image_skeleton()- plot
Logical value indicating whether a plot should be created
References
Sobel, I., and G. Feldman. 1973. A 3×3 isotropic gradient operator for image processing. Pattern Classification and Scene Analysis: 271–272.
Examples
library(pliman)
img <- image_pliman("sev_leaf_nb.jpg", plot = TRUE)
object_edge(img)
