aggregation_index {bwimage}

Aggregation index calculator

Description

The function aggregation_index calculate the aggregation index. It works for matrix with and without transparent pixel. The aggregation index is a standardized estimation of the average proportion of same-color pixels around each image pixel. First, the proportion of same-color neighboring pixels (SCNP) is calculated (marginal lines and columns are excluded). Next, the SCNP for all pixels are averaged; then, given the proportion of black and white pixels, number of pixels in height and width, and location of transparent pixels (when present), the maximum and minimum possible aggregation indexes are calculated. Finally, the observed aggregation is standardized to a scale where the minimum possible value is set at zero and the maximum value is set at one.

Usage

aggregation_index(imagematrix)

Arguments

imagematrix

The matrix to be analysed.

Value

adjusted_aggregation

Standardized aggregation.

non_adjusted_aggregation

Observed aggregation.

Author(s)

Carlos Biagolini-Jr.

See Also

threshold_color

Examples

# First, get a matrix from your image. Here an example of a bush image is used.
# Using aggregation_index to estimate vegetation agregation
bush<-system.file("extdata/bush.JPG", package ="bwimage")
bush_imagematrix<-threshold_color(bush, "jpeg", "proportional", compress_rate = 0.1)
aggregation_index(bush_imagematrix)

# Using aggregation_index to estimate aggregation of nest wall holes
nestwall<-system.file("extdata/bird_nestwall.png", package ="bwimage")
nestwall_imagematrix<-threshold_color(nestwall, "png", "width_fixed", target_width=300)
aggregation_index(nestwall_imagematrix)