Sørensen-Dice similarity coefficient for image segmentation

computes the Sørensen-Dice similarity coefficient between binary images
`similarity`

= dice(`BW1`

,`BW2`

)`BW1`

and `BW2`

.

computes the Dice index for each label in label images `similarity`

= dice(`L1`

,`L2`

)`L1`

and
`L2`

.

computes the Dice index for each category in categorical images
`similarity`

= dice(`C1`

,`C2`

)`C1`

and `C2`

.