editLayer: Edit a color patch using morphological operations

Description

Applies one of several morphological operations from imager to a layer of a recolorize object. Convenient for cleaning up a color patch without affecting other layers of the recolorized image. This can be used to despeckle, fill in holes, or uniformly grow or shrink a color patch.

Usage

editLayer(
  recolorize_obj,
  layer_idx,
  operation = "clean",
  px_size = 2,
  plotting = TRUE
)

Value

A recolorize object. The sizes, pixel_assignments,, and recolored_img attributes will differ from the input object for the relevant color patch (layer) to reflect the edited layer.

Arguments

recolorize_obj: A recolorize object from recolorize(), recluster(), or imposeColors().
layer_idx: A single index value (numeric) indicating which layer to edit. Corresponds to the order of the colors in the centers attribute of the recolorize object, and to the indices in the pixel_assignments attribute of the same.
operation: The name of an imager morphological operation to perform on the layer, passed as a string. See details.
px_size: The size (in pixels) of the elements to filter. If operation = "shrink" and px_size = 2, for example, the color patch will be shrunk by a 2-pixel radius.
plotting: Logical. Plot results?

Details

Current imager operations are:

imager::grow(): Grow a pixset
imager::shrink(): Shrink a pixset
imager::fill(): Remove holes in an pixset. Accomplished by growing and then shrinking a pixset.
imager::clean(): Remove small isolated elements (speckle). Accomplished by shrinking and then growing a pixset.

Examples

Run this code

# load image and recolorize it
img <- system.file("extdata/corbetti.png", package = "recolorize")

# first do a standard color binning
init_fit <- recolorize(img, bins = 2, plotting = FALSE)

# then cluster patches by similarity
re_fit <- recluster(init_fit, cutoff = 40)

# to reset graphical parameters:
current_par <- graphics::par(no.readonly = TRUE)

# examine individual layers:
layout(matrix(1:6, nrow = 2))
layers <- splitByColor(re_fit, plot_method = "color")

# notice patch 2 (cream) - lots of stray pixels
edit_cream_layer <- editLayer(re_fit,
                              layer_idx = 2,
                              operation = "clean",
                              px_size = 3)

# shrinking and growing by the same element size gives us less flexibility, so
# we can also shrink and then grow, using different px_size arguments:
edit_green_1 <- editLayer(re_fit,
                          layer_idx = 4,
                          operation = "shrink",
                          px_size = 2)
edit_green_2 <- editLayer(edit_green_1,
                          layer_idx = 4,
                          operation = "grow",
                          px_size = 3)

# we can get pleasingly mondrian about it:
new_fit <- re_fit
for (i in 1:nrow(new_fit$centers)) {
  new_fit <- editLayer(new_fit,
                       layer_idx = i,
                       operation = "fill",
                       px_size = 5, plotting = FALSE)
}
plot(new_fit)

graphics::par(current_par)