Advanced Mode

If your image has very fine detail or considerable noise, you'll need to take additional steps to ensure that you don't trash too much detail in the image when you're attempting to remove noise. Color images are made out of three (RGB) or four (CMYK) color components, which are known as color channels. It's rather common to find more noise in one of those channels than the others (Figures 12.20 to 12.22). When that's the case, try applying the noise removal filters to the individual channels before attempting to reduce noise from the image as a whole; otherwise, you might end up trashing the detail in most of the channels just to rid one pesky channel of noise (usually the blue or yellow channel) (Figures 12.23 to 12.25). So the next time you need to be heavy-handed with the Strength slider, try setting it to zero, switch to Advanced mode at the top of the dialog box and then click on the Per Channel tab. Once you've done that, you can cycle through the RGB or CMYK channels to see if the noise shows up more in one channel than another and adjust each channel accordingly (Figures 12.26 to 12.28). Once you've done all you can to the individual channels, you can click on the Overall tab and adjust the image further.