TVLThreshold. Color comparison ?

[yuki]

Hi all.
Let me ask TVLTheshold.

Upper limit and lower limit of the threshold can be set as.
VLThreshold1->ThresholdTop->Threshold = clWhitle;
VLThreshold1->ThresholdBottom->Threshold = clBlack;

Question:
How does VLTHreshhold1 compare colors ?
Just treats colors as 4 bytes variable ?

thanks in advance.