Evaluation of Color Pixel Representations for High Dynamic Range Digital Cinema

In 2005, the Digital Cinema Initiative (DCI) standardized a color pixel representation to ensure consistent interoperability between distributors and cinema theaters. To accurately represent the dynamic range and color gamut of both scanned film and digital, a 12-bit quantization of the XYZ color space using a gamma transfer function (TF) of 2.6 with a peak luminance of 52.37 cd/ $\text{m}^{2}$ was agreed upon. Such a selection was motivated by the need to be future-proof, device-independent, and cost-effective. This representation has been used for more than ten years with success and has been adopted throughout the digital cinema pipeline. However, several new display technologies have been proposed to increase the dynamic range of cinema display systems beyond the capabilities of the standard representation, both in bright and dark levels. Thus, to address these extra capabilities, alternative representations capable of covering larger color volumes are required. In this paper, we propose a framework to evaluate candidate color pixel representations using three characteristics: color volume, sampling accuracy, and coding efficiency. Each TF is evaluated and compared to the current DCI standard using the proposed framework. Results show a small reduction in quality is to be expected by simply updating the peak luminance up to 1000 cd/ $\text{m}^{2}$ . Further results also indicate that this reduction in quality can be compensated by modifying the color space of the pixel representation. In this paper, we propose a framework to evaluate candidate color pixel representations using three characteristics: color volume, sampling accuracy, and coding efficiency.