A Digital JPEG Capture

This image was shot with a 4.2 megapixel Canon Elph set to maximum quality. It produces a file with pixel dimensions of 1704 by 2272 pixels. Figure 6-21 shows the entire image.

Figure 6-21. A JPEG capture

Zooming in, I can see some light JPEG artifacts and some typical JPEG color noisesee Figure 6-22.

Figure 6-22. JPEG artifacts

Sharpening will make these artifacts worse, so the first task is to reduce the noise. I create a noise reduction layer using Option-Merge Visible (the file already has layers), and run Reduce Noise with the settings shown in Figure 6-23.

Figure 6-23. Noise reduction with Reduce Noise

The settings used here for Reduce Noise are about as strong as I ever use. They seem to do a good job of wiping out the JPEG artifacts, but as you'll see when I start to apply sharpening, they have a tendency to create artifacts of their own. Noise reduction and sharpening have an inherent tendency to fight one another since they basically do opposite things to the image, so I'll have to walk a fine line when I sharpen.

Sharpening for the image source is next. I create a sharpening layer using Option-Merge Visible, set to Luminosty blend at 66 percent opacity, with the Blend If sliders set to constrain the sharpening to the midtones. Then I run the Unsharp Mask filter with Amount 80, Radius 1.0 pixels, and Threshold 0, to produce the results shown in Figure 6-24.

Figure 6-24. Applying sharpening for source

This relatively gentle sharpening is enough to bring back some of the tonal JPEG artifacts (but not the color noise, fortunately). It's futile to try to eliminate these artifacts completely (unless you like images that appear to have been run through a heavy Median filter), so I'll concentrate on keeping them below the threshold of objectionability.

Next, I apply sharpening for content, as shown in Figure 6-25, using the sharpening layer with a mask made from a blur layer.

Figure 6-25. Applying sharpening for content

This image can be further improved by some selective sharpening and smoothing. I use the edge-protected smoothing brush described in "Smoothing Brushes" in Chapter 5, Putting the Tools to Work, to blur the background buildings slightly, producing more of an illusion of depth.

I use a sharpening brush like the one described in "Effects Brushes" in Chapter 5 to add some extra sharpness to the hand and the concrete arch. Finally, I use a depth-of-field brush like the one described in "Special Sharpening Brushes" in Chapter 5 to bring the paving slabs in the foreground into focus. Figure 6-26 shows the image before and after the selective adjustments.

Figure 6-26. Before and after selective adjustments

Finally, I sharpen the image for output using the same sharpening as in all the previous examples. Figure 6-27 shows the full image sharpened for output.

Figure 6-27. Sharpened for output

Real World(c) Image Sharpening with Adobe Photoshop CS2(c) Industrial-Strength Production Techniques
Real World Image Sharpening with Adobe Photoshop CS2
ISBN: 0321449916
EAN: 2147483647
Year: 2007
Pages: 71
Authors: Bruce Fraser

Similar book on Amazon

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net