Tracing around edges

Photoshop provides three filters that trace around pixels in your image and accentuate the edges. All three filters live on the Filter ^ Stylize submenu:

* Find Edges: This filter detects edges similarly to High Pass. Low-contrast areas become white, medium-contrast edges become gray, and high-contrast edges become black, as in the labeled image in Figure 11-10. Hard edges become thin lines; soft edges become fat ones. The result is a thick, organic outline that you can overlay onto an image to give it a waxy appearance. To achieve the bottom-left effect in the figure, I chose Edit ^ Fade Find Edges and applied the Overlay mode and an 80 percent Opacity setting. She'll never get her hand off that canning jar as long as she lives.

* Glowing Edges: This Gallery Effects filter is a variation on Find Edges, with two important differences: Glowing Edges produces an inverted effect, changing low-contrast areas to black and edges to white, as in the middle image in Figure 11-10. This filter also enables you to adjust the width, brightness, and smoothness of the traced edges. Glowing Edges is a great backup command. If you aren't satisfied with the effect produced by the Find Edges filter, choose Glowing Edges instead and adjust the options as desired. If you want black lines against a white background, press Ctrl+I to invert the effect.

* Trace Contour: Illustrated on the right side of Figure 11-10, Trace Contour is a little more involved than the others and slightly less interesting. The filter traces a series of single-pixel lines along the border between light and dark pixels. Choosing the filter displays a dialog box containing three options: Level, Upper, and Lower. The Level value indicates the lightness value above which pixels are considered to be light and below which they are dark. For example, if you enter 128 — medium gray, the default setting — Trace Contour draws a line at every spot where an area of color lighter than medium gray meets an area of color darker than medium gray. The Upper and Lower options tell the filter where to position the line — inside the lighter color's territory (Upper) or inside the space occupied by the darker color (Lower).

Like Mezzotint, Trace Contour applies itself to each color channel independently and renders each channel as a 1-bit image. A collection of black lines surrounds the areas of color in each channel; the RGB, Lab, or CMYK composite view shows these lines in the colors associated with the channels. When you work in RGB, a cyan line indicates a black line in the red channel (no red plus full-intensity green and blue becomes cyan). A yellow line indicates a black line in the blue channel, and so on. You get a single black line when working in the grayscale mode.

Find Edges Glowing Edges Trace Contour
Image Fade Near Borders Mask

Figure 11-10: The top row of images demonstrates the effect of the three edge-tracing commands available from the Filter ^ Stylize submenu. After applying each command, I used the Fade command to apply the blend modes and Opacity values demonstrated in the bottom row.

Overlay, 80% Overlay, 60% Multiply, 100%

Figure 11-10: The top row of images demonstrates the effect of the three edge-tracing commands available from the Filter ^ Stylize submenu. After applying each command, I used the Fade command to apply the blend modes and Opacity values demonstrated in the bottom row.

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Understanding Adobe Photoshop Features You Will Use

Understanding Adobe Photoshop Features You Will Use

Adobe Photoshop can be a complex tool only because you can do so much with it, however for in this video series, we're going to keep it as simple as possible. In fact, in this video you'll see an overview of the few tools and Adobe Photoshop features we will use. When you see this video, you'll see how you can do so much with so few features, but you'll learn how to use them in depth in the future videos.

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