README

colorSpec

colorSpec is an R package providing an S3 class with methods for color spectra. It supports the standard calculations with spectral properties of light sources, materials, cameras, eyes, scanners, etc. And it works well with the more general action spectra.

When a spectrum is contructed, a quantity is required, though it can be changed after contruction. The colorSpec quantities are typically not the same as the SI quantities; they are more general. There are 14 quantities, which then defined the 4 basic spectrum types, as given in this table from the User Guide.

colorSpec type	quantity	metric	comments	examples (objects, files, functions)
light	energy	radiometric	radiometric quantities are conventional in colorimetry	D65.1nm pos1-20x.scope BlueFlame.txt
light	photons	actinometric	for color calculations, actinometric units are automatically converted to radiometric	F96T12 Airam-GR8E.txt
responsivity .light	energy->electrical	radiometric	RGB camera response	Flea2.RGB Red-Epic-Dragon.txt
	energy->neural		eye response	xyz1931.1nm luminsivity.1nm Osmia-rufa.txt
	energy->action		examples are erythemal action, melatonin suppression, etc.	erythemalSpectrum()
	photons->electrical	actinometric	silicon sensors usually use quantum efficiency as measure of responsivity	Zyla_sCMOS.txt FoveonX3.txt
	photons->neural		response units might be photocurrent, or spikes/sec, etc.	HigherPasserines
	photons->action		photosynthesis is an example	BeanPhotosynthesis.txt
material	reflectance	NA	this is the diffuse reflectance	CC_Avg20_spectrum_XYY.txt
material	transmittance absorbance	NA	for color calculations, absorbance is automatically converted to transmittance	Hoya Hematoxylin.txt atmosphere2003
responsivity .material	material->electrical material->neural material->action	NA	a spectrum of this type typically comes from both a light source and a camera	scanner.ACES (a standard for scanning film)

Table 2.1. The types of spectra and their quantities

The quantity is used to label plots, and to make sense out of the arguments in the function product().

The function invert() implements a method in

Davis G (2019). “A Centroid for Sections of a Cube in a Function Space, with application to Colorimetry.” ArXiv e-prints. 1811.00990, https://arxiv.org/abs/1811.00990.