Lens Blur Filter – an advanced blur filter unlike any other. As compared to other blur filters (Blur, Blur More and Gaussian Blur) which blur images in its entirety, Lens Blur Filter provides more control on how one wish to blur the image. By referring to the selected Greyscale, it is able to know where to apply blur and how much to apply. We are able to achieve gradual blur using this method.
Controls in a Lens Blur Filter panel
Preview Toggle to preview before and after applying the filter (the “Faster” option is preferred as “More Accurate” takes more time to load)
Depth Map (Greyscale selection) Blur Focal Distance: Determines which shade of grey should the filter use to remain unblurred (0 being pure black). Invert: Inverts the greyscale chosen.
Iris Radius: Determines the amount of blur. The Shape, Blade Curvature and Rotation: Simulates the aperture shapes of a camera. Those shapes would be most visible at the brightest part of an image.
Specular Highlights Brightness: Dragging this slider to the right increases brightness when picture has become dull (Picture can become dull after blurring). Threshold: Determines which shades of grey to be brightened (0 being pure black).
Noise Blurred areas are rid of grains. Those unaffected areas might contain grains. Use the settings here to balance the grains of blurred and unblurred areas.
Simple example of Lens Blur Filter Examine the below pattern.
This gradient is used as my Alpha channel in the following example.
This is an example of Lens Blur using the gradient above. Notice how the image gradually blurs more at the brightest areas and remains unaffected in the darker areas.
The difference in a Gaussian Blur.
Enhancing the Depth of Field of an image Open an image and duplicate it.
Go to Windows > Channel and bring up the Channels Window. In there, click on the Add New Channel icon, using the default name “Alpha 1”.
Reset your Palette (D), fill it with white and click on the ‘reveal icon’ of RGB channel. You’re now in mask mode and can start masking.
We can use gradients, a softer or harder brush on Alpha 1 depending on the type of results you wish to achieve. Remember: the areas that we draw are the area we do not want to be affected.
Should you find the need for a softer touch, you can always blur your mask with Gaussian blur filter. The more shades of grey, the smoother the transition.
Apply your settings.
Faking Macro Mode We can also simulate/fake a camera-blurred image. Think macro mode. I’ve selected a few images below, all with similar sharpness. What I am going to do is to montage the apples as one image, and apply a natural looking camera-blur to it.
Open the images:
Crop them out, and arrange as below:
I’ve roughly created a table and added shadows to the apples.
Next, what we want to do is to create a focal point. This point should be sharp and the rest being blur. Repeat the steps above. Next, use the gradient tool to create a shade on the red apple and apply Gaussian Blur to it so that the next transition is smoother (this step is optional).
Apply the settings and we will have the results.
Blurring Focussed Portraits Below is another example of Lens Blur on an image I’ve montaged together. This time, it will focus on the model’s face and eyes while blurring the surroundings.
Below is the grey scale channel that I’ve drawn using a soft brush, gradient tool and Gaussian Blur filter.