Section 10.4. Blurring Memories

10.4. Blurring Memories

We pay so much to get the best and sharpest lenses, the highest resolution sensors, and top-rung software such as Photoshop and Lightroom, but then we spend even more money to blur all that sharpness. That's because too much detail often detracts the viewer from seeing the part of the image that we want seen. Sometimes too much sharpness just becomes motionless or static. Sometimes too much sharpness just doesn't convey that soft, silky "I'm in love" feeling. So, to make money, sometimes we have to destroy at least some of the sharpness that we spent so much time and money to get.

10.4.1. Lens Blur

The most photographic of all the Photoshop blur effects is the one that imitates what happens when you intentionally keep the lens aperture as wide as possible to minimize depth of field. We used to use the Gaussian Blur filter for achieving that effect after the shoot, but it's a bit time consuming to use feathered selections and multiple applications to create a truly photographic look. So after listening to a lot of photographer's whine (Adobe's good at listening), Photoshop CS introduced the Lens Blur filter. Figure 10-5 shows an image shot with a relative high shutter speed and small aperture. Although the model is definitely sharper than the rest of the image, the rest of the image is just too sharp to keep our attention focused on him. To make matters worse, the rest of the image was taken from another photograph and blurred slightly with the Gaussian Blur filterLens Blur filter to the rescue!

Figure 10-5. Applying Lens Blur to the background helps get our eyes back on the subject.

This is how the Lens Blur filter works best:

  1. Do all the layer stuff to the image and then follow the routine in the "Organizing Your Layers to Apply Effects" section at the beginning of this chapter so you end up with a merged layer that reflects all your adjustments, retouching, burning and dodging, and anything else you might have done.

  2. Select the area you want to keep in focus. Because there's usually some softness toward the edges of any image that has a shallow depth of field, I like to place the image in Quick Mask mode and then simply paint the mask into place, as shown in Figure 10-6. When I'm done, I click the Standard mode icon and a selection marquee appears.

    Figure 10-6. The Lens Blur dialog settings used to get the result seen in Figure 10-5.

  3. Be sure the Portrait (merged and copied) layer is selected and click the Layer Mask icon in the Layers palette. You will see the layer mask appear alongside the image icon. It will be selected, so be sure to click on the image icon to make it the target of your next step.

  4. Choose FilterBlurLens Blur. The Lens Blur dialog, shown in Figure 10-6, opens.

  5. Drag the Blur Focal Distance slider until the background seems blurred just enough. Because of the way you made the mask, the edges of the mask silhouette are a bit sharper than the immediate foreground, which is due to the fact that you used that large, feathered brush.

  6. Under Iris, choose Hexagon or Octagon as the Shape of the opening in the Iris.

  7. Drag the Iris Radius Slider to the right if you want to create an even more noticeable blur effect. It's the equivalent of using a wider aperture for a more shallow depth of field when shooting.

  8. If everything looks good to you now, zoom in to 100 percent and go back up and click the More Accurate radio button so it's on. Now look carefully and you'll notice that, regardless of your camera's resolution, there is more image noise in the foreground than in the blurred background. If you want the picture to look natural, you'll have to restore that noise, but don't overdo it. Choose Gaussian as the type and then drag the Noise slider ever so slowly to the right until you get a good match.

  9. You're done. Click OK.

10.4.2. Gaussian Blur

The Gaussian Blur filter is the old standby for blurring most anything. It's been around so long that surely anyone reading this book has been there and done that. Just be sure that when you use it on part of an image, you do it inside a feathered selection that will let the effect blend from sharp to blurry. Also remember that you'll want to match the noise in the image.

In Photoshop CS and later, there are quite a few variations on Gaussian Blur that will give you some special effects. The procedures and cautions for using them are the same as for other types of blurs. Here's a brief description of each of them.

Shape blur

You can choose from several shapes that act like diaphragm shapes in a lens blur and control their size. Sounds neat, but I haven't found a lot of important difference between them. Feel free to experiment and let me know if you discover anything super useful.

Smart blur

I'm not sure I get the difference between this and the Surface Blur filter. Smart blur blurs every thing inside an edge, but keeps the edges sharp (see Figure 10-7). The blurring is controlled by Radius and Threshold sliders. Radius controls the amount of blur. Threshold controls the difference in brightness that will be considered an edge within which all the pixels will be blurred. You can also choose to show nothing but the edges or superimpose the edges over the image. Showing nothing but the edges creates a nice mask for sharpening only the predominant edges, so you might find it well worth experimenting with.

Figure 10-7. Here you can see the Smart blur dialog and the effect that these setting produce on the macro photo of this flower.

Surface blur

Surface blur is identical to Smart blur, except that it doesn't have the Quality and Mode menus. It's the perfect tool for quickly smoothing surfaces, especially in glamour photos. Select the area you want to smooth and lift it to its own layer. If there are interior details that need to remain sharp, you can fix that later. Just run the filter (FilterBlurSurface Blur) on the lifted layer and adjust the sliders so you see just the right degree of smoothness. Click OK. Then use a feathered brush for the Eraser tool and erase through the smooth layer to the sharp details below it. As a finishing touch, use FilterNoiseAdd Noise to match the noise in the "unsmoothed portion of the image. You can see the result of having done all this in Figure 10-8.

Figure 10-8. Notice that the noise in the grainier portion of the image has been matched in the image on the right in the areas which have been "smoothed" by blurring.

10.4.3. Motion Blurs

There are so many motion blur filters that it's hard to keep track of them all. They all do the same basic thing: give the viewer the feeling are seeing an object captured while it was traveling at high speedso high that even a shutter fast enough to keep everything else in the image sharp couldn't keep the traveling object sharp.

I often find that it helps more to put a motion blur filter on an object that's been knocked out, even if that object originated in the same photograph and was just lifted from the photo. Otherwise the background smears as well as the subject. The result isn't quite as believable as when you blur a knocked-out subject, even if you've placed a selection around the image to be blurred. Figure 10-9 shows an example of both techniques so you can see the difference.

Figure 10-9. On the left, the photo of the biker as it was shot. On the right the same photo after knocking out the biker and duplicating the knocked out layer to apply the blur.

Figure 10-10 shows you the same object blurred with a third-party filter, Andromeda's Velociraptor, and a stroboscopic blur made in Photoshop, just to give you some idea of other ways to make a motion blur.

Figure 10-10. Blurred with Andromeda's Velociraptor.

There's also the Motion Trail filter in Alien Skin's Eye Candy 5: Impact (Figure 10-11). This is one of the most versatile motion blur filters because it will let you have the blur trail the object or start at its leading edge. You can also make the trail curve, taper, and change its opacity. All of this is done with sliders, so it's easy to see the effect before you apply it.

Figure 10-11. Both motion blurs were created with Eye Candy 5: Impact's motion blur filter. On the left, the blur starts trailing outside the selection or knockout. On the right, it starts on the leading edge of the selection.

10.4.4. Radial Blurs

There are two kinds of radial blurs in the Photoshop FilterBlurRadial Blur menuZoom and Radial. The Zoom blur gives the viewer the feeling of moving in fast on the subject. It got its name from the fact that if you zoomed a video camera manually at very high speed and then looked at a frame captured midzoom, it would look a lot like the result in the Zoom mode of the Radial blur filter. The Radial blur filter gives you the feeling that the subject has been captured while spinning at a high speed while sitting in the center of a high-speed turntable. Examples of both are shown in Figures 10-12 and 10-13. Each of these figures is followed by a short description of how each effect was achieved.

Figure 10-12. The Zoom blur effect moves all our attention directly to the center of the image.

Figure 10-13. Radial blur.

The problem with making the Zoom blur work for you is that it wants to blur everything from the center out. More often than not, I want to see what I'm zooming in on. So I make a duplicate layer over the original, select the duplicate layer in the Layers palette, center the zoom, set the dialog settings that I like with the Preview box checked, and click OK. Then I take a big eraser brush, set it at 100 percent Opacity and make sure the brush is feathered to the max. Then, using a pressure sensitive pen, I erase through to the original image where I do not want the image to be blurred.

Usually, a feathered selection works well with the Radial blur when it comes to keeping intact the portion of the image you want to keep sharp. However, it didn't work very well for this thistle in Figure 10-13, thanks to its thorns. So, once again, I duplicated the image and then brushed through the radial blur duplicate with the eraser tool.

What to Do When the Filter Doesn't Let You Center the Blur

The problem with blur filters is that they often blur just the thing you want to emphasize by blurring the rest of the picture. That's not always the case, but it is with all of the pictures in this blur section. The standard operating procedure (SOP) for avoiding this is to place a selection around the portion of the image you want to keep unblurred and then feather it so that the blurring graduates into sharpness when it comes to the image itself.

Another problem is that radial blurs are sharpest at the center of the blur. Most Radial blur filters will let you move the center of blur (is there really such a term?) so that you can position it where it works best. All of the filters used for the illustrations in this section provide some intuitive means of letting you do just that.

If you run into a Radial blur filter or effect that prevents you from centering the blur, just increase the size of the Canvas. Make a duplicate of the layer you want to blur and position it so that the center of the image is the center of the blur. Then run the filter. Then move the layer back to its original position by reducing its Opacity to 50 percent and drag it into place. Zoom in to 100 percent (1:1) and make sure that the details are perfectly registered atop one another in every direction.

Digital Photography(c) Expert Techniques
Digital Photography Expert Techniques
ISBN: 0596526903
EAN: 2147483647
Year: 2004
Pages: 124
Authors: Ken Milburn

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