Displaying colourimetrically calibrated images on a high dynamic range display

When colourimetrically characterising a high dynamic range display (HDR) built from an LCD panel and an LED backlight one is faced with several problems: the channels may not be constant; they may not be independent and there may be a significant radiant output at the black level. But crucially, colour transforms are underdetermined, which means that the number of colourimetric dimensions is smaller than the number of device channels. While the first three problems are associated with the LCD, the fourth problem stems from the additional channel in the HDR, the backlight.A 37″ flat-panel Brightside DR37-P HDR display was characterised. Using a spectroradiometer we recorded spectral radiance, chromaticities and luminance and estimated the true increase in gamut of the display due to the additional LED layer. We present a basic characterisation, propose a method for accurately presenting a desired luminance and chromaticity output despite the underdetermined problem and give an estimate of the available gamut.