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

Abstract

Virtual reality (VR) technology offers 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 significant new challenges, for example, due to the large field 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 defined 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, effectively enabling the use of VR technology for colour vision research.

Keywords: Colorimeter; Colour calibration; Colour constancy; Colour vision; Head mounted display; Spectroradiometer; Virtual reality.

Fig. 1

HMD colorimeter calibration setup. Vive Pro Eye and I29 with AR/VR lens.

Fig. 2

Luminance channel of an image captured by I29 from HTC Vive Pro Eye, using ProMetric.

Fig. 3

On the left: HMD primaries measured with the spectroradiometer (white dashed line) and the measured primaries using the colorimeter (black dashed line). On the right: a mixture of colours measured with the spectroradiometer (white circles) and the colorimeter (black crosses). Represented both in xy chromaticity diagram

Fig. 4

Relationship between input reflectance and luminance values measured with the colorimeter. HMD was controlled via Unreal Engine (tone mapping disabled)

Fig. 5

A mixture of colours measured with the spectroradiometer (black circles), measured colours using the colorimeter (black crosses), and the nominal values (colour filled circles). Represented in CIEL*a*b*. HMD was controlled via Unreal Engine (tone mapping disabled)

Fig. 6

Virtual Reality indoor scene. The room office contains all kind of objects, and within it we select 10 different locations for the object of interest, in this case a lizard

Fig. 7

Colour Constancy Index per illuminant. Under each illumination, 3 approaches are presented: Nominal, the nominal values and method [25]; Colorimeter, the results from colorimeter measurements and adapting method [25]; and Colorimeter CIELAB, the mean results from distances in CIEL*a*b* from colorimeter measurements. The circles represent each participant, the continuous lines the mean, the dashed line the median, together with the percentiles