Join Deke McClelland for an in-depth discussion in this video Understanding the mechanics of sharpening, part of Photoshop CS3 Sharpening Images.
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If you have the access to the sample files that are part of the series, I would like you to go ahead and open this diagram right here, it is called Sharp Shapes.PSD and it is found inside of the O1howitworks folder. That is available inside of that exercise files folder. Now this is a multi-layered illustration that is going to help us understand the mechanics of sharpening inside of Photoshop. I am going to go ahead and zoom in a little bit here. Now notice what we have is this serpentine, dark sort of line going through the image, and sprinkled inside of the line are some white circles at regular intervals and then the entire image is subjected to something of a texture pattern.
Now so far, I have not sharpened this image at all and images that have not been sharpened are sometimes know as unsharp or unsharpened, you will sometime hear them called that. And what I am going to do, because this is a multi-layered file with all sorts of layered states saved inside of it, I am going to go ahead and open up my Layer Comps palette and I would like you to do that as well. Layer Comps, as you may kNow allow you to save layered states inside of a file. If you are not familiar with the palate you can go up to the Window menu and choose the Layers Comps command. Now currently I have Layers Comps set to Standard, this is the standard view of the image, the unsharpened version of the image, compare that to the Sharpened view. I will go ahead and click in front of the word Sharpened, on that little sort of page icon right there, in order to invoke the Sharpened Layer Comp. I going to go ahead and zoom in even closer on this image, so that we can see it very close and personal at this point.
So this is the Standard version of the image, this is the Sharpened version of the image. Notice what is going on. Photoshop is going through the image and increasing the contrast of the image right where it perceives edges. So right at point of the edge it increases the contrast and it does this by tracing along the dark side of an edge, it traces a dark halo. This little tiny sort of blackish line here that is tracing outside the circle is a dark halo and then on the inside, on the bright side of this edge of this circle, we have a light halo.
In this rapid transition from dark halo to light halo, is read by our eyes when we're zoomed out from the image. It is read by our eyes as a sharp transition inside of the image. Similarly, we have got dark halo along the dark edge of the big line, of the big dark serpentine line and we have a light halo along the light edge of the line as well and then we have these halos all over inside the texture. They're are lot more difficult to make out but there are halos inside of the texture and that is whats responsible for bringing out that textures well.
So sharpening does bring out texture, it brings out noise, it brings out film grain and so on. It brigs out bad details along with the good details inside the image. Sharpening inside of Photoshop enhances contrast along edges inside of an image. Compare that to just general high-contrast effect. So I were to click on the High Contrast Layer Comp inside the Layer Comps palette, you would see a high contrast version of the image. So this is the Standard view, this is the High cContrast view but this generalized high contrast effect does not lead to more sharpness, it has to be elevated contrast along the edges in order to be read as heightened sharpness.
AlSo I would like you to also compare sharpness. I am going to go ahead and zoom in even farther on the circle here. I would like you to compare Sharpness to Jagged transitions. So sharpness taken too far can result in jagged transition, but it is ultimately a different effect. Jagged edges by themselves do not impart a sense of sharpness they just impart jagged transitions. So as you can see, here is the standard view of the image, it does have a little bit more softness but it is really smoothness as apposed to jagged transitions here.
But notice how this sharpened transitions come out very differently. So that is a first look at how sharpness works. We have heightened contrast along the perceived edges inside of the image. In the next exercise I am going to show you how sharpness works with gradual transitions.
- 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