Beyond λ[lambda]max: Transforming Visible Spectra into 24-Bit Color Values

Abstract

This article introduces the standardized definition of color, and provides a spreadsheet tool in the Supplemental Material that allows the assignment of standard 24-bit color values to solutions based upon their visible spectra. A digital photograph of several colored solutions was taken. The visible spectra of these solutions in the range of 400–700 nm were obtained with a spectral bandpass of 5 nm. The spectra were exported to a spreadsheet where they were transformed into tristimulus values, chromaticity coordinates, and standard 24-bit RGB colors. Using the spreadsheet drawing tools, a color swatch for each solution was created to display the corresponding RGB color. Finally, the digital image of the solutions was imported and compared to the color swatches to explore the differences and similarities of photographic and spectrophotometric colorimetry. The spreadsheet data analysis is emphasized in this article, since the lab procedures for obtaining visible spectra are well-established in most undergraduate curricula.