Use the sliders to define the settings for the algorithm.
Search Range: Defines the size of the area around the source block where the MEA will search for a best matching block.
Threshold: Some algorithms abort the search for one block if one special or any block has a (color space) distance below the threshold.
If one or both sliders a deactivated, this option is fixed for this certain algorithm and can not be changed.
Press "Next" when your comfortable with your selections. The calculation may take some time, depending on algorithm, search range and threshold.