Base exposure - how bright you prefer the output to be. Normal - HDR will prefer pixels exposed to 50% of max, bright - will prefer pixels exposed to 70%
Color vivdness - Black&White - no colors in output, Normal - as read out from sensor, Vivid - slight enhancement (somewhat similar to standard camera), High saturation - chroma is magnified by about 50%

There will be two additional options in upcoming release:
Contrast - contrast adjustment in output: low - as it is in current version, normal, high - increased contrast
Micro contrast - micro-contrast adjustment (to enhance texture appearance etc): low - as it is in current version, normal, high - increased micro-contrast