Digitally Simulate ‘Depth of Field'

Clive R Haynes FRPS

The procedure involves making a ‘Depth Map' to select the required area, then using the features within Photoshop (filter) ‘Lens Blur' to simulate an in-camera ‘depth of field' / ‘selective focus' effect that offers a degree of control.


The picture for this demonstration was taken in Barcelona and shows one of the 'living sculpture' artists
Before 'Depth Map'
After 'Depth Map'

The main sections of the process are:

Making a new ‘channel'

Creating an accurate selection and feathering it,

Activating the channel created

Filling the selected area to be ‘defocused' with white

Applying the ‘lens Blur' filter to manage the amount of blur and control visibility

Note: in keeping with general good imaging practice, create a ‘Copy Layer' for your image and work on this copy. You may wish to use the original (Background Layer) later.

This is what to do:

Open your image

Make a copy of the ‘Background Layer' by ‘dragging and dropping' the layer onto to the ‘Create a New Layer' icon (next to the Trash Bin). See below:

Go to ‘Channels'

Click on the New Channel icon (next to the Trash Bin)

The New Channel appears as 'Alpha 1' - and the image goes totally black - don't worry, this is is OK

Double-click on the words 'Alpha 1' and rename as 'Focus Area'




The (new) ‘Focus Area' 'channel' appears at base of the ‘Channels' palette with its associated thumbnail mask showing black


Activate RGB Channel (RGB, Red, Green & Blue Channels, all highlighted. The ‘Focus Area channel' is ‘off' – that is, not highlighted)

Looking at the image, make a selection to outline the area that you wish to remain in focus – that is ‘masked' and therefore ‘protected' from blur. Use whatever selection tools will produce the best outline for your in-focus area.

NB. To make an effective and realistic transition between the sharp area and the parts to be unsharp to simulate ‘depth of field', you'll need to soften the edges of the mask. The amount of softening will depend upon your image and your requirement. Using ‘Feathering', ‘Quick Mask' and the ‘Gradient Tools will help with this.

The worked example below illustrates how by using 'Quick-Mask', the figure is revealed and how the Gradient tool is used to give a gradual 'feathering' which will simulate the transition of 'depth-of-field'.


Note: If you're using 'Quick Mask', then don't forget that you must return to the 'Marching Ants' ('selection) mode.
To continue, click on the link below.....
Digitally Simulate 'Depth of Field' continued.....

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