Tài liệu Photoshop cs5 by Dayley part 58 doc

Part IV: Enhancing, Correcting, and Retouching 394 l Density: This allows you to set the density of the color filter. A lower density has less effect on the image, but if you use too high a density, you begin to lose detail. l Preserve Luminosity: You can specify whether to preserve the luminosity, which typi- cally is the best idea. Preserving the luminosity forces the filter adjustments to change such that the luminosity stays the same. FIGURE 13.10 Using the Photo Filter Adjustment tool, you can simulate the effect that using a color lens filter would have had when the photo was taken. You also can tweak the density and color of the filter. Replacing specific colors Photoshop allows you to selectively replace an individual color in an image with another color. This allows you to adjust the tone of a specific color range or even replace it with another set of colors. For example, you can replace a dull blue with a brighter blue or even bright yellow without changing the other colors in the image. The Replace Color Adjustment dialog box, shown in Figure 13.11, allows you to select a specific color and the tones around it and then select a replacement color. The replacement color is applied to the image replacing the original color tones without affecting any other colors. 20_584743-ch13.indd 39420_584743-ch13.indd 394 5/3/10 10:34 AM5/3/10 10:34 AM Chapter 13: Lighting and Color Adjustments 395 FIGURE 13.11 Using the Replace Color tool, you can replace specific colors in an image. Eyedroppers Selection view The Replace Color Adjustment tool allows you to adjust the following settings: l Localized Color Clusters: This specifies whether to select only color clusters that are contiguous to each other. Using this option makes color selection a bit more accurate when the color is localized to one area of the image. However, if the color is spread throughout the image, do not use this option. l Eyedroppers: The eyedroppers allow you to select colors from the image. The plus drop- per adds to the selection; the minus dropper removes the color from the selection. The adjusted selection is displayed below the droppers. l Color: This allows you to use a color chooser dialog box to select a specific color to replace from any available color in Photoshop. l Fuzziness: This specifies the range of tones to include in the selection color. Low fuzzi- ness means that only tones close to the selected color are chosen. High fuzziness means that a broader range of tones is included. 20_584743-ch13.indd 39520_584743-ch13.indd 395 5/3/10 10:34 AM5/3/10 10:34 AM Part IV: Enhancing, Correcting, and Retouching 396 l Selection view: This shows the selection as white with non-selected areas of the image as black, so you can see what areas of the image will be affected by the color replacement. l Selection/Image: This allows you to toggle the selection view between the selection and the actual image. This helps you see how the color selection relates to the image. l Hue: This adjusts the hue of the color that will replace the existing color in the image. l Saturation: This adjusts the saturation of the replacement color. Adjusting the saturation up deepens the change; adjusting the saturation down tones down the replacement color. l Lightness: This adjusts the lightness of the color that will replace the existing color in the image. l Result: The result color swatch displays the resulting color from the Hue, Saturation, and Lightness adjustments. You also can click the color swatch to launch a color chooser and use it to specify a color. The following steps take you through an example of using the Replace Color Adjustment tool to replace the color in an image: 1. Open the image in Photoshop, as shown in Figure 13.12. 2. Select Image ➪ Adjustment ➪ Replace Color to load the Replace Color dialog box shown in Figure 13.11. FIGURE 13.12 The rose in the image is a basic red that is about to change in the following steps. 20_584743-ch13.indd 39620_584743-ch13.indd 396 5/3/10 10:34 AM5/3/10 10:34 AM Chapter 13: Lighting and Color Adjustments 397 3. Use the eyedropper to select a color in the image. In this case, select one of the petals of the rose. Notice how those color tones have been added to the selection view in Figure 13.13, but that much of the rose remains unselected. 4. Adjust the fuzziness up or down to adjust the selection. In this case, the rose is the only thing red in the image, so we adjust the fuzziness all the way up and almost the entire rest of the rose is added to the selection, as shown in Figure 13.13. 5. Use the plus and minus eyedroppers to fine-tune the selection. In the example, we used the plus dropper to add some of the missing parts of the selection while leaving only the darkest and lightest tones in the rose, as shown in Figure 13.13. FIGURE 13.13 Using the eyedropper to select a color creates a small selection; increasing the fuzziness increases the selection to include more of the similar tones; and finally using the plus dropper, we select the rest of the rose. 6. After you have the selection finalized, adjust the hue to the replacement color. You can also click the Color box to open a color chooser to select the color. In the exam- ple, we changed the red in the rose to a blue, as shown in Figure 13.14. 7. Adjust the saturation and lightness to get the best effect in the image. In the example, we increased the saturation by +6 to deepen the blue a bit and then decreased the brightness by −11 to compensate. The results are shown in Figure 13.14, where the rose is now blue, but the green background remains unchanged. 20_584743-ch13.indd 39720_584743-ch13.indd 397 5/3/10 10:34 AM5/3/10 10:34 AM Part IV: Enhancing, Correcting, and Retouching 398 FIGURE 13.14 Adjusting the hue, saturation, and lightness of the selected color changes the rose from red to blue. On the Web Site The image shown in Figure 13.14 can be found on this book’s Web site as Figure13-14.psd. The adjustment was made to a duplicate layer so you can see both images. n Using the Variations tool The Variations Adjustment tool in Photoshop allows you to easily make the most of the general color correction changes that Photoshop has to offer from a single interface. The Variations Adjustment tool is extremely useful if you are editing images and you’re not quite sure what color correction needs to be made. The biggest strength of the Variations Adjustment tool is that you can preview all possible changes as thumbnails in the same view before you make them. You also can adjust only the highlights, midtones, shadows, or saturation and specify the coarseness of changes. To use the Variations Adjustment tool, select Image ➪ Adjustment ➪ Variation from the main menu in Photoshop to launch the Variations dialog box, shown in Figure 13.15. From the Variations dia- log box, you can view and make the following adjustments: l Original/Current Pick: This displays the original and current images side by side so you can always see the differences that the change has made. l Shadows: This specifies to make adjustments only to the shadows in the image. Using this option allows you to make both color and lighting corrections to the darker areas of the image. l Midtones: This specifies to make adjustments only to the midtones in the image. Using this option allows you to make both color and lighting corrections to midtones of the image. 20_584743-ch13.indd 39820_584743-ch13.indd 398 5/3/10 10:34 AM5/3/10 10:34 AM Chapter 13: Lighting and Color Adjustments 399 FIGURE 13.15 Using the Variations Adjustment tool, you can quickly see possible color, lighting, and satu- ration adjustments in thumbnails and then apply the changes by clicking the thumbnail. 20_584743-ch13.indd 39920_584743-ch13.indd 399 5/3/10 10:34 AM5/3/10 10:34 AM Part IV: Enhancing, Correcting, and Retouching 400 l Highlights: This specifies to make adjustments only to the highlights in the image. Using this option allows you to make both color and lighting corrections to the lighter areas of the image. l Saturation: This specifies to make adjustments only to the saturation of pixels in the image. Using this option allows you to make saturation adjustments to the image. l Fine/Coarse: This adjusts how coarse the adjustments should be. Adjusting this to Fine makes subtle changes, and adjusting it up to Coarse makes much more dramatic adjustments. l Show Clipping: When you adjust pixels in the images such that their level value goes out of range (below 0 or above 255), the pixel data is lost because the values out of range are clipped back into range. l Color adjustments: This allows you to add more of any color hue to the image by click- ing more color thumbnails, as shown in Figure 13.15. This option is available for adjust- ing the shadows, midtones, or highlights in the image. Note Adding colors is not additive. For example, if you click More Yellow twice and then More Blue twice, the pixels in the Current Pick are back to the original state. n l Lightness adjustments: This allows you to increase or decrease the lightness levels to the shadows, midtones, or highlights in the image. l Saturation adjustments: When the Saturation option is selected, you can use these adjustments to add and remove saturation from the image. Changing the shadows and highlights in images Adjusting shadows and highlights is a great way to correct or enhance photos to give them addi- tional depth and detail. Many lighting and color adjustments tend to focus on the entire tonal range, but adjusting shadows and highlights allows you to add detail that is lost in the upper and lower ranges without affecting the midrange colors that make up most of an image. Photoshop provides the Shadows/Highlights Adjustment tool, shown in Figure 13.16, that allows you to work with only the upper or lower tonal ranges in an image. Using the Shadows/Highlights Adjustment tool, you can focus in on specific problems where areas of an image are too bright or too dark, causing limited detail. You also can use the Shadows/Highlights Adjustment tool to make subtle corrections to images to increase the detail and contrast. To use the Shadows/Highlights Adjustment tool, select Image ➪ Adjustments ➪ Shadows/Highlights from the main menu in Photoshop. Fixing shadows The Shadows aspect of the tool allows you to bring back some of the detail lost in areas of the image that are too dark due to backlighting issues, for example. To fix the shadows in an image, use the following adjustments in the Shadows/Highlights Adjustment tool shown in Figure 13.16: l Amount: Controls how much correction to make to the shadows in the image. Increasing this value results in a more dramatic correction. However, if you increase the value too much, the corrected values may cross over and become brighter than the highlights in the image. 20_584743-ch13.indd 40020_584743-ch13.indd 400 5/3/10 10:34 AM5/3/10 10:34 AM Chapter 13: Lighting and Color Adjustments 401 l Tonal Width: Sets the range of tones that are involved in the correction. Increasing this value results in more of an effect on the midtones and highlights in the image. Decreasing this value results in only the shadows being affected. When you are trying to correct only a dark area of the image, you should decrease the tonal width to close to zero. l Radius: Determines how many surrounding pixels to use to determine if an area falls in the Shadows tonal range. A smaller radius value means that fewer pixels are used and the shadow correction will be more precise. However, if the radius is too small, some areas of the image may not be corrected properly. You need to play around with the radius until the adjustment provides the best outcome. Tip Set the Radius to roughly the size of the subjects of interest in the image. This ensures that those subjects are most accurately corrected. n Fixing highlights The Highlights aspect of the tool allows you to focus in on areas of the image that are too bright. For example, you can correct areas in the image that are overexposed due to a flash or direct sun- light. To fix the highlights in an image, use the following adjustments in the Shadows/Highlights Adjustment tool shown in Figure 13.16: l Amount: Controls how much correction to make to the highlights in the image. Increasing this value results in more of a dramatic lighting correction. However, if you increase the value too much, the corrected values may cross over and become darker than the shadows in the image. l Tonal Width: Sets the range of tones that are involved in the correction. Increasing this value results in more of an effect on the midtones and shadows in the image. Decreasing this value results in only the highlights being affected. When you are trying to correct only a dark area of the image, you should decrease the tonal width to close to zero. l Radius: Determines how many surrounding pixels to use to determine if an area falls in the highlights tonal range. A smaller radius value means that fewer pixels are used and the highlights correction will be more precise. Adjusting after shadows or highlights are corrected After you have adjusted the shadows or highlights, you may need to adjust the color and contrast in the full image to make the image look more natural. To make adjustments to the color and con- trast of the image after fixing highlights and shadows, use the following adjustments in the Shadows/Highlights Adjustment tool shown in Figure 13.16: l Color Correction: Adjusts the saturation of the colors in the areas of the image that have been corrected by the shadows and highlights adjustments. This option is available only in color images. Increasing this value adds more color, and decreasing it reduces the amount of color. Typically, you want to add more color to areas of the image that were too dark or too light because those areas tend to have less color detail than the rest of the image and will look a bit odd. 20_584743-ch13.indd 40120_584743-ch13.indd 401 5/3/10 10:34 AM5/3/10 10:34 AM Part IV: Enhancing, Correcting, and Retouching 402 l Brightness: Adjusts the brightness of the entire grayscale image. This option is available only for grayscale images. Increasing this value increases the brightness, and decreasing it reduces the brightness. l Midtone Contrast: Adjusts the contrast in the midtone pixels of the image. Use this option to help the midtones match the adjusted shadows and highlights. Increasing this value increases the contrast in the midtone pixels only. l Black Clip: Specifies how much the shadows are clipped to level 0 when adjusting the shadows. Increasing this value provides greater contrast; however, too much of this value results in loss of detail. l White Clip: Specifies how much the highlights are clipped to level 255 when adjusting the highlights. Increasing this value provides greater contrast; however, too much of this value results in loss of detail. Figure 13.16 illustrates the effects of using the Shadows/Highlights Adjustment tool to correct an image that has been negatively affected by the lighting conditions. Notice that the original image has dark and light areas with not much detail because too much light is reflecting off the lake. After adjusting the shadows, highlights, and midtones, the darker areas include more detail and the brightness of the lake is toned down. FIGURE 13.16 Using the Shadows/Highlights Adjustment tool, you can quickly adjust problems with areas of an image being too light or too dark. 20_584743-ch13.indd 40220_584743-ch13.indd 402 5/3/10 10:34 AM5/3/10 10:34 AM Chapter 13: Lighting and Color Adjustments 403 On the Web Site The image shown in Figure 13.16 can be found on this book’s Web site as Figure13-16.jpg. Check out the file on the Web site and make the changes shown in the example to see the detail come back and the brightness get toned down. n Creating customized black and white photos When you convert a color image into a black and white photo, you are really combining three channels (red, green, and blue) of data into only one grayscale channel. This can be done in any number of ways. However, there are three main concepts. One way to convert a color image to grayscale is to use only one of the three channels, for exam- ple, only the red channel. The problem is that this gives you only the red data in the image, leaving much of the detail out. This works well for some effects, but you likely want more detail in your image. Another way is to use a combination of the three channels. For example, you could create grayscale data by taking 40 percent of the red value, 40 percent of the green value, and 20 percent of the blue value and adding them together to get the value for each grayscale pixel. By using the best combination of the three channels, you can get the most detail out of the image. This works very well, as you learned in the Channel Mixer section of Chapter 11. In fact, this is the default method that Photoshop uses to convert color images to grayscale and is the recommended method of con- version. A little bit more complex way to generate the grayscale data from the color channels is to focus on percentages of each color tone. This allows you to maximize the amount of detail, best contrast, and overall appearance of the resulting black and white photo. The drawback to this method is that it requires some guesswork and a bit of trial and error to get the best effect. The Black and White Adjustment tool, shown in Figure 13.17, allows you to use combinations of reds, greens, and blues, as wells as cyans, magentas, and yellows to generate the grayscale data in the black and white image. By specifying percentages of these color tones, you can customize the resulting levels that go into the grayscale channel of the black and white photo. Tip When you use the Black and White Adjustment tool to create black and white photos, keep in mind that increasing the percentage of a color lightens those pixels in the resulting image. Decreasing the percentage of a color darkens those pixels in the resulting image. For example, if you want to darken the sky in the black and white photo, you would decrease the percentage of blue that is included in the resulting image. n To use the Black and White Adjustment tool to create a customized black and white photo, select Image ➪ Adjustments ➪ Black & White from the main menu in Photoshop to launch the Black and White dialog box shown in Figure 13.17. Then use the adjustment sliders to set the amount of each color to include when creating the grayscale channel. 20_584743-ch13.indd 40320_584743-ch13.indd 403 5/3/10 10:34 AM5/3/10 10:34 AM . adjustments in thumbnails and then apply the changes by clicking the thumbnail. 20 _584 743-ch13.indd 39920 _584 743-ch13.indd 399 5/3/10 10:34 AM5/3/10 10:34 AM Part IV: Enhancing, Correcting, and Retouching 400 l. is now blue, but the green background remains unchanged. 20 _584 743-ch13.indd 39720 _584 743-ch13.indd 397 5/3/10 10:34 AM5/3/10 10:34 AM Part IV: Enhancing, Correcting, and Retouching 398 FIGURE. fuzziness means that a broader range of tones is included. 20 _584 743-ch13.indd 39520 _584 743-ch13.indd 395 5/3/10 10:34 AM5/3/10 10:34 AM Part IV: Enhancing, Correcting, and Retouching 396 l Selection