tailieunhanh - Photoshop 6 for Windows Bible- P17

Photoshop 6 for Windows Bible- P17:If you are reading this foreword, it probably means that you’ve purchased a copy of Adobe Photoshop , and for that I and the rest of the Photoshop team at Adobe thank you. If you own a previous edition of the Photoshop Bible, you probably know what to expect. If not, then get ready for an interesting trip. | Chapter 10 Corrective Filtering 449 Sharpened Threshold 0 Figure 10-14 The original Ike is a bit soft left a condition I can remedy with Unsharp Mask. Leaving the Threshold value set to 0 brings out the film grain middle but raising the value results in equally unattractive artifacts right . While we wait for Photoshop to give us a better Threshold one with a Fuzziness slider or similar control you can create a better Threshold using a very simple masking technique. Using a few filters that I explore at greater length throughout this chapter and the next you can devise a selection outline that traces the essential edges in the image complete with fuzzy transitions and leaves the nonedges unmolested. So get out your favorite old vintage photograph and follow along with these steps. STEPS Creating and Using an Edge Mask 1. Duplicate one of the color channels. Bring up the Channels palette and drag one of the color channels onto the little page icon. Ike is a grayscale image so I duplicate the one and only channel. 2. Choose Filter StylizeFind Edges. As I explain in Chapter 11 the Find Edges filter automatically traces the edges of your image with thick gooey outlines that are ideal for creating edge masks. 3. Press Ctrl I. Or choose Image AdjustInvert. Find Edges produces black lines against a white background but in order to select your edges you need white lines against a black background. The Invert command reverses the lights and darks in the mask as in the first example in Figure 10-15. 450 Part III Selections Masks and Filters Find Edges Invert Sharpened edges Find edge mask Figure 10-15 I copy a channel find the edges and invert left . I then apply a string of filters to expand and soften the edges middle . After converting the mask to a selection outline I reapply Unsharp Mask with winning results right . 4. Choose Filter Noise Median. You need fat gooey edges and the current ones are a bit tenuous. To firm up the edges choose the Median filter enter a value