Join Deke McClelland for an in-depth discussion in this video Understanding sharpening and noise reduction, part of Photoshop CS3 Sharpening Images.
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In this exercise we are going to take a look at combining sharpening with noise removal. Inside the Photoshop I am looking at this Sharp Shapes.PSD file, that's found inside of the 01howitworks folder. The same file that we've been working with for the previous two exercises. I have the Layer Comps palette set to the Standard Layer Comp, which contains the texture, notice that. I'll go ahead and zoom-in on this image and you can see that texture pattern in the background. Imagine that this texture is something that we don't want to sharpen, we want to defeat the texture, and this texture could be something like noise captured by a digital camera, it could be noise captured by scanner, it could be dust and scratches, it could be film grain associated of course with film transparencies or color negatives, something along those lines, and we want to get rid of that noise before we begin sharpening, and that's the right order to work incidentally. You want to apply Noise Removal first and then apply your Sharpening, and so I've got ahead and done that inside of this diagram here.
If you go down the Layer Comps palette, you'll see that there is a Layer Comp called Noise Removal. Go ahead and click on it in order to remove some of the noise from the image. Now notice that I am saying SOME of the noise/texture in this case, because you are not going to get rid of all of it. If you're trying to get rid of all of the noise inside of an image or all of the film grain or all of the texture then you're going to get rid of your good detail as well. In our case, we are pretty fortunate here; I've managed to get rid of most of the texture while preserving the good details, the serpentine line and the circles and so on.
So this is the Standard view with the texture, this is the Noise Removal view right here. Now notice, if we apply Sharpening on top of Noise Removal that we get a much cleaner result. So we have these nice-sharpened edges without bringing out the texture. This is a big difference here, compare that to sharpening with the texture. So if we'd sharpened without applying any Noise Removal we bring out a ton of texture inside the image. If we apply Noise Removal first and then apply our Sharpening we get very clean results.
I've also got a Layer Comp that shows the same thing where the Gradient view of the image is concerned. I'll go ahead and zoom back out here for a moment. You may recall, here's our gradient view from the previous exercise. Here's the gradient version of the image subjected to noise removal upfront, and its made only a small difference, you may not even notice it at that zoom level, so I'll go ahead and zoom back in, so that we can see the difference. It's just a little bit. Here's the gradients version of the image with texture, here's the gradient version of the image without texture.
So there wasn't that much texture going on. Once again though, it makes a big difference when we apply Sharpening. So this is the sharpened version of the texture defeated image, of the noise removal image, and this is the sharpened version right here of the noise image, or the image with texture. So you can see that the sharpened version has brought out a ton of texture. If we hadn't taken the time to get rid of the texture in the first place, we're going to bring that texture out with Sharpening, whereas if we take the time to apply some noise removal, even just a little bit, we're going to get much cleaner results as we are seeing here. And again, you should bear in mind, this isn't perfect.
If I zoom in on this low-contrast area, you can see that we have some pretty wonky edges in this Sharp Grad NR Layer Comp right here, and that's because Photoshop is going in there and actually finding some weird edges where the gradient is concerned, where the combination of gradient and noise removal texture is concerned. So we still do have some weird transitions. It is an imperfect process, but if you're trying to get rid of the texture, it's heck of a lot better than this version right here.
So remember that apply your Noise Removal first and then apply your Sharpening when you are trying to fix your beautiful photographs. In the next exercise, we're going to see how you can control the degree of Sharpening that you apply to an image, using the amount and Radius values. Stay tuned.
- Understanding the effects of sharpening
- In-depth examinations of Unsharp Mask, Smart Sharpen, Emboss, and High Pass
- Smoothing an image with the Surface Blur, Despeckle, and Reduce Noise features
- Working with smart objects and smart filters
- Creating edge masks and non-edge masks
- Sharpening for digital-image capture using Camera Raw
- Gauging and exploiting luminance frequency
- Exploring creative applications of sharpening
- Sharpening a multilayer composition
- Sharpening eyes, hair, and out-of-focus backgrounds
- Reducing noise in a high-frequency image
- Determining ideal settings for commercial and inkjet output
- Sharpening very large-format images
- Sharpening an image for the web or screen output