Rowles Media, Design & Photography

Depth of Field Effect

// February 19th, 2008 // No Comments » // Tutorial

In this little tutorial we are going to create what is sometimes refered to as a fake depth of field effect. Basically we are going to blur the background of an image using a lens blur effect. This tutorial forms part of a shortcourse that I deliver called ‘Photoshop – Enhanced’, although sometimes I add it on to ‘Photoshop – The Basics’ depends on how fast the delegates are catching on!

Firstly we need to create a selection based on the background of an image. Open Blur Masking original. Now in order to select the background we need to use a combination of the magic wand tool, and the lasso. This requires some patience but the effect will be worth it.

Set the tolerance quite high, about 40 on the magic wand and click on area of background, then to select more hold down the shift key. You may find that you select to much, when this happens select the lasso tool, hold down Alt and lasso the areas you want to deselect.

 

Once you have this all selected go to ‘Select / Save Selection’. In the pop up window select name and name your selection ‘background’. This will now appear in the channels palette as a new channel. Now we are going to create another channel, this time from within the channel palette, select the new channel icon (same as the new layer icon).  

Now select the gradient tool and and fill the canvas with a gradient fill.The gradient fill will be black and white. It needs to start with black at the bottom of the image as above.  Now we have two new channels which we now need to combine. Doing this requires us to open the Calculations window. This is at ‘Image / Calculations’.      

Above are the settings you need to apply, this calculations window allows you merge two images, layers, or channels together from any two psd files. In this case our two sources are from the same PSD file ‘blurmasking.psd’, we want to merge them, and the two sources are channel ’Gradient’, and channel ‘background’. Finally we want the result to be a ‘New Channel’. Now we can use this new channel as the basis for the lens blur effect. Now making sure you have your image layer selected go to ‘Filter / Blur / Lens Blur’. 

The new window that appears is the lens blur options window. There are many settings you can play with and feel free to have a go. But the main thing you need to do is set the ‘Depth Map’ source to the merged channel you have created, to select it click on the dropdown menu next to  source and select ‘alpha 1’. This will change the mostly blurred preview to a nicely blurred background, and sharp subject.

 

Your finished product should look something like the below image.