Low-complexity lookup table construction with reduced interpolation error

A method of constructing, in a decoder, a lookup table for prediction of high dynamic range image data from standard dynamic range data received by the decoder, the method comprising:

• accessing a prediction function for the prediction of the high dynamic range image data;
• generating a first set of nodes for a first lookup table (LUT), using the prediction function, wherein each node is characterized by an input node value and an output node value;
• modifying the output node value of at least one node in the first set of nodes to generate a second set of nodes in a second lookup table, for generating predicted high dynamic range output values, said modifying comprising:
• for a current node in the first set of nodes:
• determining a first prior node and a second prior node to the current node, wherein the first prior node is closer to the current node than the second prior node;
• determining a first slope between the first prior node and the current node;
• determining a second slope between the second prior node and the first prior node;
• determining a first tangent slope to the first prior node based on the first slope and the second slope;
• determining a first modified slope based on the first tangent slope, the first slope, and a weighting parameter;
• and
• determining a first modified output value of the current node based on the first modified slope and the first prior node;
• generating, based at least in part on the high dynamic range image data, a high dynamic range output video signal for playback.