Averaging pixels with Median

Another command in the Filter ^ Noise submenu, Median removes noise by averaging the colors in an image, one pixel at a time. When you choose Filter ^ Noise ^ Median, Photoshop produces a Radius option box. For every pixel in a selection, the filter averages the colors of the neighboring pixels that fall inside the specified radius — ignoring any pixels that are so different that they might skew the average — and applies the average color to the central pixel.

You can now enter any value between 1 and 100. However, even at the old limit, 16, significant blurring occurs, as you can see from the bottom right example in Figure 10 41 (in the preceding section). At the maximum Radius value, you wind up with a sort of soft, blurry gradient, with all image detail obliterated.

As with Gaussian Blur, you can achieve some very interesting and useful effects by backing off the Median filter with the Fade command. But rather than creating a Star Trek glow, Median clumps up details, giving an image a plastic, molded quality, as demonstrated by the examples in Figure 10-42. To create every one of these images, I applied the Median Filter with a Radius of 5 pixels. Then I pressed Ctrl+Shift+F to display the Fade dialog box and lowered the Opacity value to 70 percent. The only difference between one image and the next is the blend mode.

Another difference between Gaussian Blur and Median is that Gaussian Blur destroys edges and Median invents new ones. This means you can follow up the Median filter with Unsharp Mask to achieve even more pronounced sculptural effects. I sharpened every one of the examples in Figure 10-42 using an Amount value of 150 percent and a Radius of 1.5.

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