---
title: "Introduction to spectra2rgb"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Introduction to spectra2rgb}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r setup, include = FALSE}
knitr::opts_chunk$set(collapse = TRUE, comment = "#>")
```

## Overview

`spectra2rgb` converts hyperspectral reflectance signatures to sRGB hex
codes and CIELAB coordinates. It bundles the CIE 1931 standard observer
and D65 illuminant, so no external colour-science package is required.

## Quick start

```{r}
library(spectra2rgb)

wl  <- seq(400, 700, by = 10)
ref <- 0.1 + 0.6 * exp(-((wl - 550) / 60)^2)   # synthetic green peak

hs_to_xyz(wl, ref)
xyz_to_rgb(hs_to_xyz(wl, ref))
```

## Data-frame workflow

```{r}
set.seed(1)
wl  <- seq(400, 700, by = 10)
mat <- matrix(runif(5 * length(wl), 0.1, 0.9), nrow = 5)
colnames(mat) <- as.character(wl)
df  <- as.data.frame(mat)

spectra_to_rgb_lab(df, id_col = paste0("leaf_", 1:5))
```

## Missing values

```{r}
df2 <- df
df2[2, ] <- NA

# Silent zero-fill (default):
spectra_to_rgb(df2, na_action = "zero")

# Drop with warning:
suppressWarnings(spectra_to_rgb(df2, na_action = "drop"))

# Preserve NA:
spectra_to_rgb(df2, na_action = "keep")
```