Creative Focus with Lens Blur In Photoshop

Step 6: Paint With White On The Alpha Channel To Control The Blurring Effect

With my Brush Tool selected and my brush opacity lowered to 50%, I'm going to make sure my Foreground color is set to white so that I'll be painting with white, and then I'll begin creating my Depth Map by painting on the alpha channel to control how much blurring will be applied to different areas of the image.

For this image, I want to reduce the amount of blurring that will be applied to the woman's face in general, so with a large, soft-edged brush, I'm simply going to click once over her face:

To change the size of your brush, use the left and right arrow keys on your keyboard. The left bracket key makes the brush smaller and the right one makes it larger. To make the edges of your brush nice and soft, hold down your Shift key and press the left bracket key a few times. Holding Shift and pressing the right bracket key a few times makes the brush edges harder.

It's a bit hard to see in the image, but after clicking once over the woman's face, which added some white to that area on the alpha channel, some of the red in that area has disappeared. The area I clicked on will now have a bit less of a blurring effect applied to it when we go to use the Lens Blur filter. The rest of the image will have blurring applied at a full 100%.

I want to reduce the blurring amount even further over her eyes, nose and mouth, so I'm going to press my left bracket key a few times to reduce the size of my brush and then I'm going to paint in one continuous motion over her eyes, nose and mouth, making sure not to release my mouth button at any point while I'm painting so I maintain the same level of white across that whole area, which will maintain the same reduced blurring amount:

It's now becoming a bit easier to see that the red is disappearing from the areas I've painted on, as I increase the amount of white in those areas on the alpha channel. I think I want to reduce the amount of blurring even further over her lips and eyes, so I'm going to keep my brush the same size and just paint once again over those areas:

We can now definitely see the original image showing through the red in those areas, which means they will receive the least amount of blurring, and since we're using a soft-edged brush, we'll get smooth transitions between the different levels of blurring.

Finally, I want to really bring focus and attention to the woman's eyes so I don't want any blurring being applied to them at all. To make sure no amount of blurring is applied to them, I'm going to simply click a few times with my brush over each eye, filling those areas with pure white on my alpha channel and removing any hint of red from them in the image:

I've now completed the work on my alpha channel and I can go ahead and use it as my Depth Map with the Lens Blur filter, which I'll do next, but before we do that, if I want to see what my alpha channel really looks like, all I need to do is click once again on the eyeball icon to the left of the RGB channel in the Channels palette to turn the channel off again, which will leave only the "Alpha 1" channel visible, and I can now see exactly where I've painted with white on it at various opacity levels. The two areas that appear brightest on the alpha channel are where I clicked several times over her eyes:

We have our Depth Map. Now let's put it to work.

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