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Draw viewers in with a well-defined focal point

Added on Thursday 5th of April 2012 03:48 am EST
 

by Amy Gebhardt
Application:
Adobe Photoshop CS2/CS3/CS4/CS5
Operating Systems:
Macintosh, Microsoft Windows
 

If your images are lacking impact, it could be a simple fix—sometimes all it needs is a focal point. Lucky for you Photoshop’s Lens Blur filter is a great tool for this job!

 

To add a focal point with the Lens Blur filter, we’ll:

  1. Give you an overview on the Lens Blur filter.
  2. Go over the different options offered in the Lens Blur dialog box.
  3. Show you how to use layer masks and alpha channels to control the intensity and placement of the blur.

 

One of the best methods to create a focal point in an image is to apply a slight blur to the surrounding elements. In a sense, this forces viewers to see what you want them to see, and it’s a subtle enough technique that the blur won’t detract from the overall image. Photoshop’s Lens Blur filter enables you to create more realistic-looking and highly controlled blurs. Let’s take a closer look.

 

Understanding all of your options
When you first open the Lens Blur dialog box, shown in Figure A, you may feel a bit overwhelmed by all of the different options presented to you. However, it’s these options that allow you to have a great deal of control over any alterations you make to your image. Let’s go over them now.

A
 

 

Depth Map
In the Depth Map section, you can specify the pixels within your image that you want blurred. For example, if you choose None from the Source pop-up menu, then Photoshop applies the blur to every pixel evenly. This is because you aren’t using a depth map; you’re just applying the blur. If you select Transparency, Photoshop applies the blur to the image based on the transparency of each pixel. If you select Layer Mask from the Source pop-up menu, then the blur is based on the grayscale values within the mask. Finally, if you select a custom-made alpha channel, the blur is based on the grayscale values within that channel. By default, any of the black areas within your image are designated as the foreground, and the white areas or transparent areas are designated as the background. The pixels established as the background will be blurred.


Along with assigning a depth map, you can also adjust the Blur Focal Distance by moving its slider back and forth. If you set the value to 0, the black pixels will be in focus; if you set the value to 255, the white pixels will be in focus. Any setting in between the two extremes will cause a gray value to be in focus. Besides making adjustments using the slider, you can also click anywhere on the image preview to take a sample of a specific value. Then, that sampled area will determine the focal distance.

 

Iris
If you’re a photographer or familiar with photography, then you’ll probably have a good understanding of the Iris options in the Lens Blur dialog box. Generally speaking, the way an actual photograph looks with a lens blur applied is in part due to the iris (or aperture) in the camera lens. When applying a lens blur in Photoshop, you can choose from six different iris shapes. The more complex the shape, the smoother your blur will be.


The Radius setting controls the amount of blur you apply to your image. You can adjust the Blade Curvature and Rotation settings to create imperfections within the blur or to bring out detail. It’s best to experiment with different settings to see how these controls work. The results can be very subtle.

 

Specular Highlights
Typically, when you apply any of the Blur filters to an image, Photoshop averages the pure white areas into other surrounding darker pixels and those areas become gray. The Lens Blur filter’s Specular Highlights options give you control over how these pixels are blended. If you want to brighten any white areas of your image, just increase the Brightness value (move the slider to the left). Then, you can decrease the Threshold slider (move it to the right) to increase the number of areas affected by the highlight or increase the slider to limit the areas being affected.

 

Noise
Although Photoshop has a Noise filter already, the Noise options in the Lens Blur dialog box are priceless. The concept is the same, except you can add noise to the blurred portions of your image, making it match the original film grain without ever leaving the dialog box.

 

Defining the focal point
Now that you’re familiar with all of the Lens Blur filter’s options, let’s test out the filter. Open an image to work with or use the file flag.jpg, available from the URL listed at the beginning of this article. (Images provided by PhotoSpin. Some images modified ...