Masking in Photoshop

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