PsyCalibrator: An Open-Source Package for Display Gamma Calibration and Luminance and Color Measurement

Abstract

Studies in vision, psychology, and neuroscience often present visual stimuli on digital screens. Crucially, the appearance of visual stimuli depends on properties such as luminance and color, making it critical to measure them. Yet conventional luminance-measuring equipment is not only expensive but also onerous to operate (particularly for novices). Building on previous work, here we present an open-source integrated software package—PsyCalibrator (https://github.com/yangzhangpsy/PsyCalibrator)—that takes advantage of consumer hardware (SpyderX, Spyder5) and makes luminance/color measurement and gamma calibration accessible and flexible. Gamma calibration based on visual methods (without photometers) is also implemented. PsyCalibrator requires MATLAB (or its free alternative, GNU Octave) and works in Windows, macOS, and Linux. We first validated measurements from SpyderX and Spyder5 by comparing them with professional, high-cost photometers (ColorCAL MKII Colorimeter and Photo Research PR-670 SpectraScan). Validation results show (a) excellent accuracy in linear correction and luminance/color measurement and (b) for practical purposes, low measurement variances. We offer a detailed tutorial on using PsyCalibrator to measure luminance/color and calibrate displays. Finally, we recommend reporting templates to describe simple (e.g., computer-generated shapes) and complex (e.g., naturalistic images and videos) visual stimuli.