While the Alpha channel of the picture is selected, in the Filter menu choose Gaussian Blur from the Blur submenu. Change the Radius size until you’re satisfied with the result. In this tutorial I used 0.9 in the Radius field (Fig.06).
Fig.06
Step 9 :
Now in the Channel tab select the RGB channel. It will show your original picture (Fig.07).
Fig.07
Step 10 :
Go to the Filter menu and this time choose Lens Blur from the Blur submenu.
Step 11 :
In Depth Map Source select Alpha channel. Now if you click on each object or place in your picture you will find that the camera will focus on it and the rest of scene will be blurry. You can also change the distance with Blur Focus Distance. The Radius value will set the maximum and minimum amount of blurring. And in the Noise group you can add noise to the blurry area (Fig.08).
Fig.08
So simply you can create DOF effect in any area of your picture with compositing 3ds Max and Photoshop. Just keep in mind that this composition cannot always work accurately!
