Multi-Band Spectral Fusion

Builds a colour composite by equally averaging three groups of measured bands. Averaging may reduce independent band noise but does not calibrate values. Explicit groups may overlap; singleton groups are allowed, including identical channels from one band. Each channel uses its own stretch.

Usage

hsa_fusion(
  cube,
  red = NULL,
  green = NULL,
  blue = NULL,
  by = c("index", "wavelength"),
  stretch = c("percentile", "range", "none"),
  probs = c(0.02, 0.98),
  display_limits = c(0, 1),
  value_label = "input value",
  interpolate = TRUE,
  missing = c("propagate", "available")
)

Arguments

cube

An hsi_cube (from hyperspectR) or a 3-D array with dimensions (rows, cols, bands), of integer or double values. Optional wavelengths metadata must be finite, unique and strictly increasing in nm. Without it, coordinates are band indices. An optional logical spatial mask has dimensions (rows, cols) and no missing entries; FALSE excludes a pixel. Arrays may carry these as attributes; an hsi_cube may carry them as list fields. Nonfinite observations are excluded.

red, green, blue

Integer vectors of band indices, or numeric wavelengths in nm when by = "wavelength". NULL (default) splits the spectrum into three contiguous thirds, long wavelengths to red.

by

Either "index" (default) or "wavelength".

stretch

Contrast stretch: "percentile" (default), "range" or "none".

probs

Percentiles for stretch = "percentile". Default c(0.02, 0.98).

display_limits

Two increasing finite endpoints used as the fixed colour domain for stretch = "none". Default c(0, 1).

value_label

A truthful label for the input values. Default "input value". A reflectance label requires known upstream calibration; numeric range alone cannot establish calibration.

interpolate

Logical; interpolate raster pixels. Default TRUE.

missing

Missing-band policy. "propagate" (default) requires every selected band; "available" averages the finite contributors in a group.

Value

A ggplot2 object.

Examples

cube <- hsa_demo_cube()
hsa_fusion(cube)