Step 2: Check Each Channel For Noise

The first item to do is to check each of the channels to find out where the noise might be and to see if we can minimize it by lightly applying filters on one or two channels.

■ If the Channels palette is not currently displayed, choose Window >- Channels to display the Channels palette. Click the Red channel (Ctrl+1) in the Channels palette to view the Red channel. Your Channels palette should look like the one shown in Figure 11.3 and the document window should now have a black and white image of the owl, such as the one shown in Figure 11.4. Considerable noise is in this channel.

■ Click the Green channel (Ctrl+2) in the Channels palette to get a black and white image, such as the one shown in Figure 11.5. Remarkably less grain is here, which is good.

■ Click the Blue channel (Ctrl+3) in the Channels palette to get a black and white image,

11.4 11.5

such as the one shown in Figure 11.6. As can usually be expected, you find the most grain in the Blue channel. I'm not optimistic about being able to remove much grain from any of these channels as the owl itself has so much important detail in the edges of the feathers — minimizing grain can necessarily mean loss of important detail, too.

■ Click the RGB channel in the Channels palette to once again make the RGB channel visible. The Channels palette should now look like the one in Figure 11.7.

With some images, you find that you can use a small amount of Gaussian Blur or other blur filter on one or two channels to remove a substantial part of the unwanted grain. But, this is not true for this image. Consequently, we have to come up with another

11.6

strategy. For this image, we are mostly concerned about removing the noise from the background, not the owl itself. So, duplicate the background layer; blur the background to remove noise, and then create a layer mask that allows the grain-free background layer to show thorough.

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