Masking in Photoshop
1. duplicate original layer (layer>duplicate)
2. click on duplicated layer. (image>adjustments>desaturate)
3. use marquee tool (draw rectangle on desaturate layer)
4. whist marquee active click on MASK icon
5. finally (image>adjustments>invert).
Results:-
 |
with Mask |
 |
with Mask |
 |
without Mask |
 |
with Mask |