Join Deke McClelland for an in-depth discussion in this video Understanding sharpening and gradual transitions, part of Photoshop CS3 Sharpening Images.
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In this exercise I am going to show you what happens to those dark and light halos when we are tracing an image that contains gradual transitions. I am still working inside the Sharp Shapes.PSD file that's found inside the 01howitworks folder. I've got my Layer Comps palette open and I am going to switch- right now we are looking at the Standard Layer Comp- I am going to switch down to the Gradients Layer Comp, this one right here. So this is an alternate view of the image. It still contains the texture pattern but instead of having a dark serpentine line set against a light background, we've got a gradient, a dark to light gradient serpentine line set against a light to dark gradient background.
So we've got some opposite gradients going on right here. That will allow us to see what happens to those halos as I was saying, when we have gradual transitions. And you can see that. Let's go ahead and zoom in on this image so we can really take it in close and personal once again, so it translates to the video, and I am going to switch over here to Sharp grads, this guy right here, this Layer Comp. And notice that we Now toward the top of the image, notice that I am looking at the top region of the image where the serpentine line is dark and the background is light, and we have a pretty familiar pattern of halos here. We have dark halos around the outside of the circles for example and light halos around the inside of those circles.
As I pan down, the farther that I pan down and the closer that we get to this region where the gradients are pretty similar to each other, where we just have a bunch of midtones going on. Notice that the edges, those halos, drop out. So the halos actually get thinner and thinner and decline here almost like calligraphic brush strokes, this one is happening here, its almost like lading up off the pressure of a stylus, for example. So that the dark edge is just disappearing, the dark halo is just disappearing. And then it switches places. Then we start seeing a light halo emerging as the gradient serpentine line becomes lighter than its background.
So what was formally a dark halo transitions to a light halo and what was formally, in this case up here, a light halo on the outside transitions very slowly to a dark halo down toward the bottom and so they gradually and automatically switch places. So Photoshop is intelligent enough not only to the detect the edges inside the image and increase the contrast of those edges, but also to trace the light halos, always on the light side of the edge and the dark halo along the dark side of the edge, and the lightness or darkness of those halos is commensurate with the degree of contrast.
So down here toward the bottom of the image where we have the highest degree of contrast between the white serpentine line and the dark background, we have very nearly a white halo on the inside and that black halo on the outside, and those halos become less and less defined as the natural contrast between the edges grows less defined as well, so that you can see that those halos just start becoming not only more tapering but they also start growing darker, the light halo grows darker and the dark halo grows lighter as well.
So there we have it to look at sharpened edges inside of a gradually transitioning image. In the next exercise, I am going to show you the effects of combining sharpening with noise reduction inside Photoshop.
- 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