HDR (High Dynamic Range) and WCG (Wide Color Gamut) increase significantly quality of viewing experience by rendering impressive images and videos. Automatic assessing the quality of these HDR WCG images is one crucial objective in broadcast process. Full-reference HDR metrics have been designed in the last years to achieve this objective:HDR-VDP2, HDR-VQM, PU-encoding metrics. Recent studies have pointed out that HDR-VDP2 is one of the best metric. Unfortunately, HDR-VDP2 is quite complex to use due to numerous and sometimes hard-to-know parameters such as display emission spectrum, surround luminance and angular resolution. In this paper, we show that HDR-VDP2 does not require an accurate knowledge of the viewing condition parameters. For that, we not only test the impact of these parameters on existing image databases of subjective quality scores, but also we propose a new and complementary image database made with a different HDR display.