Color Difference Metrics

Dibakar Raj Pant

Friday 17th of February Dibakar Raj Pant defended his doctoral thesis about color difference metrics.

Dibakar Raj Pant has been affiliated with Université Jean Monnet in France, and the work has been performed at the Colorlab at Gjøvik University College. The defense of the Ph.D. thesis was held at Gjøvik University College.

The title of the Ph.D. thesis is «Line Item and variational Methods for Color Difference Metrics.»

More than a century ago, the first mathematical model for the measurement of color differences, a color metric, was developed. Since then, many metrics have been developed. Such metrics are used to quantify the accuracy of color reproduction for example in displays and cameras.

Dibakar Raj Pant has developed a mathematical method to translate the metric between different color presentations to be able to compare the different metrics with each other and with experimental observations. The comparisons confirm existing knowledge about the quality of some existing metrics.

Pant has also examined the relationship between color metrics and color attributes such as brightness, saturation and hue. Schrödinger put forward a hypothesis in 1920 that the attributes in principle could be derived mathematically from the metric. This hypothesis has never been tested properly. In the thesis, the hypothesis is tested by trying to derive the color attributes for four of the most widely used color metrics. The results differ a lot, but the experimentally observed attributes is well within the variation found between the attributes derived from the different metrics. Shrödinger's hypothesis is not disproved this time either, and it still remains to find a really good color metric.

Dibakar Raj Pant has been under the supervision of Professor Alain Tremeau at Université Jean Monnet and Assosciate professor Ivar Farup at Gjøvik University College.