Use Tolerance
to adjust the number of shades of a color that are selected when using a tool such as Flood Fill 
or Magic Wand 
. A higher tolerance increases the range of color shades that are selected, and a lower tolerance reduces the range of shades.
A Tolerance value of 0 will select only pixels that exactly match, whereas a value of 100 will select all pixels.
Drag the Tolerance
slider to choose the range of color shades that will be selected with Tolerance.
Tolerance can be used with: Flood Fill 
, Flood Erase 
and Magic Wand 
.