Tài liệu Photoshop cs5 by Dayley part 33 doc

Part II: Working with Camera Raw Images 226 Adjusting Color and Clarity Adjusting the color of a raw image can be done in the Basic panel for a general fix, the Tone Curve panel for a targeted fix, and the HSL panel for a highly precise adjustment that allows you to make custom decisions about your color in eight different color ranges. Don’t be overwhelmed with all this ability for changing and adjusting the color of your images. As with most areas (in life as well as in Photoshop), it’s best to start with the basics and work up, depending on how much control you want to have over the color. Working with in Photoshop is an art form, not a science—even when it comes to correcting color. Although the basic tools are fairly simple and straightforward, adjusting tonal curves takes a little practice and effort before you can do it well without thought, and adjusting color levels in the HSL panel can very quickly get out of hand! The best way to become proficient is to jump in and work with these tools until you feel comfortable using them to adjust the photos that really matter. Clarity, vibrance, and saturation Clarity, vibrancy, and saturation can be adjusted in the basic panel of Camera Raw. These adjust- ments are basic not because they are not powerful, but because they are so useful and commonly used that the default panel is the best place for them. They also are the easiest of the color adjust- ments to use and to get right. As well as improving the color and clarity of your images generally, these settings can compensate for loss of color and clarity due to the tonal adjustments. This is a great way to create stunningly colorful images, similar to taking pictures with a high-saturation film. You can adjust the clarity and saturation of your image by adjusting these sliders: l Clarity: This adjustment clarifies the edges in the image, restoring definition and sharpness lost to the tonal adjustments. It works by increasing the contrast of the midtone pixels. This works like magic to reduce hazy or dull images that are a result of the conditions when the image was shot or using other settings that reduce contrast, such as the Brightness slider. See the difference in the before and after images in Figure 8.14, for instance. The first image is very hazy and blah. The second image takes advantage of the Clarity adjustment to make a dramatic difference in the clarity and crispness of the image. On the Web Site Try your hand at adjusting the clarity of the before image saved as Figure 8-14 on the Web site. n l Vibrance: This adjustment saturates only the areas of the image that are of a lower satura- tion without affecting the areas that are already highly saturated. It also leaves skin tones alone, making it ideal for saturating images with human subjects. l Saturation: This adjustment saturates the image uniformly, giving you the ability to reduce the colors in your image to grayscale or to increase the color of your image to as much as double the saturation. Colorful photos, such as flowers or balloons, are especially fun to over-saturate in order to create a color statement. 13_584743-ch08.indd 22613_584743-ch08.indd 226 5/3/10 10:23 AM5/3/10 10:23 AM Chapter 8: Processing Photos in the Camera Raw Workspace 227 FIGURE 8.14 A change using just the Clarity adjustment made a big difference in this image. Tone Curve Placing the Tone Curve under the heading for adjusting color isn’t exactly precise, because it adjusts the lightness of your image as much as the color. The Tone Curve gives you more control over which areas of your photo are brightened or darkened, as well as which colors pop and which fade. It takes practice to get a feel for exactly how the curve works, however, so you might find yourself inadvertently making drastic and unwanted changes. You can easily restore the default set- tings and start over, though, so don’t despair. I’ll do my best to demystify the Tone Curve so your practice has purpose. The Tone Curve panel has two tabs: the Parametric tab, which allows you to make limited changes to the Tone Curve using sliders, and the Point tab, which allows you to make changes to the Tone Curve using points on the curve itself. The Parametric panel It’s harder to take your changes too far with the Parametric tab over the Points tab because it limits the changes you make to sliders. It’s quicker, easier, and generally more user-friendly. On the other hand, it doesn’t give you near the latitude for making changes as the Points tab. 13_584743-ch08.indd 22713_584743-ch08.indd 227 5/3/10 10:23 AM5/3/10 10:23 AM Part II: Working with Camera Raw Images 228 The first thing you should note in the Parametric tab, shown in Figure 8.15, is the histogram within the Parametric settings that represents the tonal layout of your image. In the image shown in Figure 8.15, most of the pixels are in the midtone range or higher, as you can see by the high peaks in the middle and to the right. As a general rule, you would look at this histogram and know immediately that the photo it represented was low on contrast. That isn’t a bad thing for some images, but this one is hazy and unclear, and it has enough shadow that there should be plenty of pixels in the lower end of the histogram. This is a photo that definitely will benefit from a tonal curve correction. FIGURE 8.15 In the Parametric Tone Curve, the histogram represents the tonal layout of this image. Note It’s important to look at images in conjunction with their histograms to decide whether the histogram repre- sents areas that need to be corrected. A picture taken on a snowy day might resemble the histogram in Figure 8.15 and look bright and clear. The histogram by itself is not an indicator of whether an image is a good one or in need of improvement. Instead, it is a guide to help you make the right changes to improve your image. n 13_584743-ch08.indd 22813_584743-ch08.indd 228 5/3/10 10:23 AM5/3/10 10:23 AM Chapter 8: Processing Photos in the Camera Raw Workspace 229 On the Web Site Figure 8.15 needs lots of work. Changing the Parametric Tone Curve improves it so much. Give it a try by downloading Figure 8-15 from the Web site and following the steps for changing the tonal curve. n Fix the photo shown in Figure 8.15 by following these steps: 1. Adjust the indicators directly under the histogram so they represent a more balanced tonal range, as shown in Figure 8.16. This doesn’t change your image, but it affects how the tonal sliders underneath affect your image. The Shadows slider adjusts the pixels left of the first indicator, the Darks slider adjusts everything between that indicator and the next, and so on. 2. Adjust the Shadows slider. In this image, the dark and shadow pixels need the most work, so it’s best to start there. Move the slider to the left to darken the shadow in the image. Click the shadow clipping warning in the main histogram to preview any shadows that are being clipped. (You won’t find any in this photo, but it’s a good habit to get into.) Stop when you are satisfied with the result. 3. Adjust the Darks slider. With the balanced histogram shown in Figure 8.16, this slider is really touchy and cre- ates an image that is too dark with very little adjustment. FIGURE 8.16 Adjusting the indicators determines how the sliders affect the image. 4. Adjust the indicators under the histogram again. In order to get a better result with the Darks slider, adjust the middle indicator farther left, so the second pixel spike is to the right of the indicator. 5. Adjust the Darks again. 13_584743-ch08.indd 22913_584743-ch08.indd 229 5/3/10 10:23 AM5/3/10 10:23 AM Part II: Working with Camera Raw Images 230 Now, as you move the Darks slider, you get a better range to play with. Again, stop when you see that you’ve found a good balance. 6. Adjust the Lights slider. This slider also needs to move left, but not much. 7. Adjust the Highlights slider. Moving this slider right adds contrast to the image. Again, you should take advantage of the highlight clipping warning in the main histogram. You can find clipped highlights in this image. You can continue to tweak the indicators and the sliders to get a feel for the changes they are mak- ing and to get the best final result. When you are finished, you should have a result similar to Figure 8.17. Add Clarity and Contrast to this photo, and you have a finished product that is practi- cally a miracle considering what you began with. FIGURE 8.17 With these final settings, you can already see a marked improvement in the photo. 13_584743-ch08.indd 23013_584743-ch08.indd 230 5/3/10 10:23 AM5/3/10 10:23 AM Chapter 8: Processing Photos in the Camera Raw Workspace 231 The Point tab The Point tab gives you much more latitude for changing your image, but using that capability is more difficult. I show you how to correct the same image used in Figure 8.15 by using the Points panel instead of the Parametric panel: 1. Click the Panel menu, and choose Camera Raw Defaults to reset the image. If you used the Parametric tab to change the curves, you want to start over from the origi- nal image settings. You should have the image and settings shown in Figure 8.18. FIGURE 8.18 The Points Tone Curve 2. Use the drop-down menu to choose Strong Contrast. This changes the curve based on a Strong Contrast preset. It’s an improvement to the image, but not enough. 3. Move the points on the curve. The location of these points on the curve performs a similar function to the indicators in the Parametric histogram. By changing their location on the diagonal, you can change 13_584743-ch08.indd 23113_584743-ch08.indd 231 5/3/10 10:23 AM5/3/10 10:23 AM Part II: Working with Camera Raw Images 232 which pixels are affected as you use them to bend and stretch the curve. Change these points closer to the histogram so more tones are affected by each, as shown in Figure 8.19. Note that as soon as you do this, the Curve drop-down menu changes to Custom. Tip You can add points to the curve by clicking the curve where you want to add one. You can remove a point by dragging it quickly off the curve. n FIGURE 8.19 Move the points on the histogram so more tones are affected by their adjustment later. 4. Adjust the lower-left point first. The biggest change you want to make to the photo is to increase the dark areas for more contrast, so start with this point first. Move the point slowly down. You can drag it up and down the curve line as you do this to further customize your adjustment. Tip For more controlled adjustments, use the arrow keys to move the selected point by increments of one. The up and down arrow keys adjust the curve, and the side keys adjust the point placement on the curve. n 5. Click to add a point lower on the curve. The shadows in this photo are too washed out for my taste. Adding another point lower on the curve gives you more control over them. 6. Continue to move the points on the curve, adding more when necessary. This is where all the practice and skill comes in. Each photo reacts differently, and you’ve probably noticed that even a small change can really mess up your image. Just keep working with it until you get the result you want. 13_584743-ch08.indd 23213_584743-ch08.indd 232 5/3/10 10:23 AM5/3/10 10:23 AM Chapter 8: Processing Photos in the Camera Raw Workspace 233 Note The Input field tells you the actual value of the pixel you are adjusting; the output field tells you what value you are adjusting the pixel to. n It doesn’t take long adjusting the Point curve before you can see that it is indeed more versatile, but also much more difficult to control. Because I could add points to the curve, the end result was better than I achieved with the Parametric adjustment, as you can see in Figure 8.20. Notice that the background above the cliffs is much clearer because I added another point to the highlights. FIGURE 8.20 The Points adjustment is more precise, bringing out more detail. HSL adjustments Figure 8.21 shows the HSL/Grayscale panel. HSL stands for Hue, Saturation, and Luminance. Each setting has a panel, and the color sliders in each panel allow you to make changes to the color in these precise color ranges. 13_584743-ch08.indd 23313_584743-ch08.indd 233 5/3/10 10:23 AM5/3/10 10:23 AM . areas (in life as well as in Photoshop) , it’s best to start with the basics and work up, depending on how much control you want to have over the color. Working with in Photoshop is an art form,. of your image by adjusting these sliders: l Clarity: This adjustment clarifies the edges in the image, restoring definition and sharpness lost to the tonal adjustments. It works by increasing. improves it so much. Give it a try by downloading Figure 8-15 from the Web site and following the steps for changing the tonal curve. n Fix the photo shown in Figure 8.15 by following these steps: