Tài iệu Photoshop cs5 by Dayley part 95 doc

Part VI: Artistic Effects 668 FIGURE 20.12 Moving the Accented Edges effect below the Splatter effect can change the end result on the image dramatically. Using Smart Objects to Make Non- Destructive Filter Adjustments Applying filters directly to your images changes the actual pixel values and modifies the original data. Although you can use the History option to get back to the original state, after you save your file, those pixels have been altered beyond recovery. Additionally, you may need to try several filter methods and sometimes combinations of filters to get the adjustment you are looking for, which is hard to do when you are trying to apply more than one filter, especially if some of your filters are not found in the Filter Gallery. That is where Smart Objects can make a huge difference. When you apply a filter to a Smart Object, it is applied as a Smart Filter that can be turned on and off, adjusted, reordered, and easily removed without destroying the underlying pixel data. The best way to apply filters to images in a non-destructive way is to create a duplicate layer of the background and then turn that layer into a Smart Object. You also can simply turn the background 29_584743-ch20.indd 66829_584743-ch20.indd 668 5/3/10 10:41 AM5/3/10 10:41 AM Chapter 20: Applying Filters 669 layer into a Smart Object layer, but if you keep the background layer around, you can always cre- ate a new duplicate layer later to try another set of Smart Filters on. Use these steps to create a duplicate of the background layer and then apply Smart Filters to it: 1. Open the image in Photoshop. 2. Right-click the background layer, and select Duplicate Layer from the pop-up menu shown in Figure 20.13. This displays the Duplicate Layer dialog box. 3. Name the layer in the Duplicate Layer dialog box, shown in Figure 20.13, and click OK to create the layer. The new layer is added to the Layers panel. FIGURE 20.13 By creating a second layer, the original layer is preserved in its original state. 4. Right-click the new layer, and select Convert to Smart Object from the pop-up menu shown in Figure 20.14. The layer is converted to a Smart Object, and the layer thumbnail includes a Smart Object icon as shown in Figure 20.14. 5. Select Filter ➪ Artistic ➪ Watercolor to apply a Watercolor filter to the Smart Object. When the Filter Gallery open, make adjustments to the filter and click OK. The Watercolor filter is applied as a Smart Filter to the Smart Object, as shown in Figure 20.15. 29_584743-ch20.indd 66929_584743-ch20.indd 669 5/3/10 10:41 AM5/3/10 10:41 AM Part VI: Artistic Effects 670 FIGURE 20.14 A Smart Object has a Smart Object icon on the layer thumbnail. FIGURE 20.15 When a Smart Filter is applied to a Smart Object, it becomes a sublayer, easily viewable and editable. 6. Select Filter ➪ Brush Strokes ➪ Accented Edges to apply the Accented Edges filter to the Smart Object. When the Filter Gallery opens again, make adjustments to the fil- ter and click OK. The Accented Edges filter is applied as a Smart Filter above the Watercolor filter, as shown in Figure 20.16. 29_584743-ch20.indd 67029_584743-ch20.indd 670 5/3/10 10:41 AM5/3/10 10:41 AM Chapter 20: Applying Filters 671 FIGURE 20.16 Additional filters appear on the Layers panel, with the most recent one on top. 7. Drag and drop the Accented Edges filter below the Watercolor filter to change the look of your image, as shown in Figure 20.17. FIGURE 20.17 With a simple drag and drop, the order of the filters has been changed, changing the effect on the image. 29_584743-ch20.indd 67129_584743-ch20.indd 671 5/3/10 10:41 AM5/3/10 10:41 AM Part VI: Artistic Effects 672 8. Make other changes to your filters as you desire by right-click any Smart Filter to display the menu shown in Figure 20.18. You can choose any of these menu options, or you can perform these functions by doing the following: Edit the filter settings by double-clicking the filter name. Double-click the Blending Options icon (to the right of the filter name) to change the Blend mode of that filter over your image. You also can disable the filter by clicking the “eye”-con. Or you can delete the filter entirely by dragging the filter to the trash icon. FIGURE 20.18 Smart Filters are easily editable as well as non-destructive. Creating a Custom Filter One of the most powerful filters Photoshop provides is the Custom filter. The Custom filter gives you the ability to define most of the behavior of Photoshop’s filter algorithms. Most of Photoshop’s filtering algorithms work by focusing on one pixel at a time. Photoshop evaluates the color/bright- ness of the surrounding pixels and uses various algorithms to calculate what the new color/bright- ness of the current pixel should be. Then the algorithm moves to the other pixels until it has filtered every pixel in the image. Note Many of Photoshop’s filtering algorithms apply multiple filtering effects and even additional algorithms that are not available through the Custom filter. You can get some pretty good results with the Custom filter, but you cannot duplicate the results you can get in some of the other filters in Photoshop. n Applying a Custom filter is done by selecting Filter ➪ Other ➪ Custom from the main menu in Photoshop to launch the Custom dialog box shown in Figure 20.19. The Custom dialog box allows you to apply a weight to each of the neighboring pixels as well as the surrounding pixels when cal- culating the replacement pixel value. In addition to the weight for neighboring pixels, you can specify scale and offset values: l Scale: The Scale value allows you to control the weight ratio between the center pixel and the surrounding pixels. Photoshop reduces the resulting pixel value by dividing it by the value of the scale. This allows you to apply filters that scale pixel values out of the 0–255 range by scaling them back in. 29_584743-ch20.indd 67229_584743-ch20.indd 672 5/3/10 10:41 AM5/3/10 10:41 AM Chapter 20: Applying Filters 673 l Offset: The Offset value allows you to give an overall offset in brightness that is applied to the resulting pixel. Increasing the offset can compensate filters that tend to make the image too dark; decreasing the offset can compensate for filters that make the image too light. FIGURE 20.19 Using the Custom dialog box in Photoshop allows you to define filters by setting weights for surrounding pixels, a scale value, and an offset value. Here’s how it all works. Photoshop selects a pixel, multiplies it by the center value in the Custom filter, takes the surrounding pixels defined in the Custom filter, and multiplies them by the corre- sponding values. Then it adds them all up, divides by the scale, and adds the offset to that number. This might be a bit confusing at first, but look at the example filter shown in Figure 20.19; con- sider a pixel with the value of 100, one pixel up is 200, one pixel down is 200, one pixel left is 150, and one pixel right is 150. This equation is used to calculate the value that replaces the cur- rent pixel: (100x10+200x-1+200x-1+150x-1+150x-1)/5 + 0 = 60 Tip A good rule of thumb when creating Custom filters is to try to make the value of the equation equal 1 if all of the pixel values are set to 1. From there, you can tweak the values a bit and use the offset to adjust any major problems. n As you play around with the Custom filter tool, you start to realize the limitless possibilities of fil- ters you can create with it. The following are some examples of different types of filters that can be created with the Custom filter tool shown in Figure 20.20: l No Filter: Applying a value of 1 for the current pixel applies no filter. l Sharpen: Applying negative values symmetrically to the surrounding pixels and a positive value to the current pixel sharpens the image. l Blur: Applying positive values symmetrically to the surrounding pixels and a positive value to the current pixel blurs the image and removes dust. 29_584743-ch20.indd 67329_584743-ch20.indd 673 5/3/10 10:41 AM5/3/10 10:41 AM Part VI: Artistic Effects 674 l Directional Blur: Applying positive values in only one direction to the surrounding pixels and a positive value to the current pixel blurs the image only in the direction of the pixel changes. l Enhance Edges: Applying positive values symmetrically to the surrounding pixels and a negative value to the current pixel enhances edges in the image. l Highlight Edges: Applying negative values symmetrically to corner pixels and a negative value to the current pixel highlights the edges in the image. l High Contrast: Applying extremely high values for both the surrounding pixels and the current pixel results in a high-contrast effect. FIGURE 20.20 Some example Custom filters High Contrast Hightlight EdgesEdge Detection Directional BlurBlur SharpenNo Filter 29_584743-ch20.indd 67429_584743-ch20.indd 674 5/3/10 10:41 AM5/3/10 10:41 AM Chapter 20: Applying Filters 675 Summary This chapter presented a comprehensive listing of the artistic filters and learned how to apply them through the Filter menu and the Filter Gallery. You learned more about Smart Filters and how they work to create a non-destructive sublayer on your image that can be edited, moved, or deleted. And if being able to use more than a hundred filters, add them to each other, and change their set- tings and blending modes doesn’t give you enough options, you can use the Custom filter settings to create just the look you want. You should know how to do these things: l Find the right artistic filter to get your desired results l Use the Filter Gallery to apply a filter or multiple filters l Create a Smart Object in order to add Smart Filters 29_584743-ch20.indd 67529_584743-ch20.indd 675 5/3/10 10:41 AM5/3/10 10:41 AM . surrounding pixels. Photoshop reduces the resulting pixel value by dividing it by the value of the scale. This allows you to apply filters that scale pixel values out of the 0–255 range by scaling them. in Photoshop allows you to define filters by setting weights for surrounding pixels, a scale value, and an offset value. Here’s how it all works. Photoshop selects a pixel, multiplies it by. most powerful filters Photoshop provides is the Custom filter. The Custom filter gives you the ability to define most of the behavior of Photoshop s filter algorithms. Most of Photoshop s filtering