Colour Calibration of a Head Mounted Display for Colour Vision Research Using Virtual Reality

Virtual reality (VR) technology ofers vision researchers the opportunity to conduct immersive studies in simulated real-world scenes. However, an accurate colour calibration of the VR head mounted display (HMD), both in terms of luminance and chromaticity, is required to precisely control the presented stimuli. Such a calibration presents signifcant new challenges, for example, due to the large feld of view of the HMD, or the software implementation used for scene rendering, which might alter the colour appearance of objects. Here, we propose a framework for calibrating an HMD using an imaging colorimeter, the I29 (Radiant Vision Systems, Redmond, WA, USA). We examine two scenarios, both with and without using a rendering software for visualisation. In addition, we present a colour constancy experiment design for VR through a gaming engine software, Unreal Engine 4. The colours of the objects of study are chosen according to the previously defned calibration. Results show a high-colour constancy performance among participants, in agreement with recent studies performed on real-world scenarios. Our studies show that our methodology allows us to control and measure the colours presented in the HMD, efectively enabling the use of VR technology for colour vision research

Assessment of OLED Head Mounted Display for Vision Research with Virtual Reality

Vision researchers often rely on visual display technology to present observers with controlled stimuli, usually by means of a calibrated computer screen. Virtual Reality (VR) may allow a similar level of control, together with higher realism of the stimulation and a visual field larger than what is achievable on a standard computer monitor. To produce the desired luminance and color of the stimuli, accurate characterization of the spectral properties of the display is necessary. However, this process might not be trivial on VR displays, because 1) the Head Mounted Displays (HMD) used in VR are typically designed to be light-weight and low energy consuming, thus they might not meet some of the standard assumptions in display calibration, 2) the VR software might affect the color and luminance signal in a complex way, further complicating the calibration process. Here we show that 1) a common, off-the-shelf display used in our experiments behaves similarly to a standard OLED monitor, 2) the VR gaming engine we tested (Unreal Engine 4) introduces a complex behavior, 3) which can be disabled. This allows to accurately control colors and luminance emitted by the display, thus enabling its use for perceptual experiments