Tài liệu Photoshop cs5 by Dayley part 54 pps

Part IV Enhancing, Correcting, and Retouching IN THIS PART Chapter 12 Adjustment Workflow Chapter 13 Lighting and Color Adjustments Chapter 14 Sharpness, Blur, and Noise Adjustments Chapter 15 Using Cloning and Healing to Restore Digital Images 18_584743-pp04.indd 36718_584743-pp04.indd 367 5/3/10 10:32 AM5/3/10 10:32 AM 18_584743-pp04.indd 36818_584743-pp04.indd 368 5/3/10 10:32 AM5/3/10 10:32 AM 369 CHAPTER Adjustment Workflow IN THIS CHAPTER Adjustment workflow Making auto adjustments Using the Adjustment panel E very edit you make to your photo alters the pixels, reducing the qual- ity and increasing the possibility of bruising—visible areas of pixel distortion. Even if your edits are made using non-destructive layers, the visible end result is the same. Some adjustments are more destructive than others, so creating a workflow that takes you from least destructive to most is a very important step in achieving the best results possible. As you add Adjustments to your image, the fastest and most efficient way to do so is using the Adjustment panel. You can use icons for a quick-click to add and edit adjustments without having to open and select adjustments from a menu. The adjustments added from the Adjustment panel are added as non-destructive adjustment layers. This chapter explains the importance of workflow and introduces you to the Adjustment panel. Understanding Workflow Using an organized workflow to edit your images is not only the best way to make edits in the most non-destructive way, it’s a good organizational habit to get into so you aren’t inadvertently skipping important steps in correcting your photo. Not all images need all corrections, of course, but you’ll want to follow the same order for each one, skipping steps when they aren’t required. Here’s a good workflow to follow: 19_584743-ch12.indd 36919_584743-ch12.indd 369 5/3/10 10:33 AM5/3/10 10:33 AM Part IV: Enhancing, Correcting, and Retouching 370 1. Correct your photos in Camera Raw. Whether your photos are raw images, TIFFs, or JPEGs, you can open them in Camera Raw, make relatively quick, non-destructive changes to them, and then save them or open them in Photoshop. Follow the same workflow in Camera Raw as in Photoshop to create your edits. Note If you open a JPEG in Camera Raw and make changes to it, you must save it as a TIFF, PSD, or DNG file to pre- serve the metadata and keep the edits non-destructive. After you save your changes to a JPEG file, they become part of the image and you cannot reverse them. n 2. Open your image in Photoshop. Whether you are coming from Bridge, Camera Raw, or another program, this step is a no- brainer if you want to edit your image in Photoshop. 3. Crop, straighten, and resize your photo. Unless you want several different aspect ratios (such as 4x6 and 8x10), you want to crop your photo strictly to the area you want. 4. Correct overall lighting. Correcting the lighting in your image is usually instrumental in correcting the color, so it should always be done first. 5. Correct the overall color. After you’ve corrected both lighting and color in your image, it should look pretty good, with lighting and color at the best settings and evenly distributed across your image. Now you are ready to make targeted adjustments. 6. Clean the unwanted elements out of your photo using the Clone Stamp and Healing Brushes. While your lighting and color is still uniform, you want to clean up scratches, lens spots, blemishes, or stray elements in your photo that distract from the subject. These tools in Photoshop are fantastic and create realistic results, but bruising is an unavoidable result of using them. 7. Combine images. If you are combining two or more images to create a collage or special effect, now is the time to do it. If you are using the Clone tool to create head swaps or otherwise add ele- ments from one photo into another, you want to make sure the lighting and color are as uniform between the two images as possible before you begin. This makes the next step much easier. 8. Make targeted lighting adjustments. 19_584743-ch12.indd 37019_584743-ch12.indd 370 5/3/10 10:33 AM5/3/10 10:33 AM Chapter 12: Adjustment Workflow 371 When your image is uniformly correct, you can start correcting areas in your image that are still not ideal, such as an overexposed sky. You can make these adjustments by creat- ing a selection or mask so the adjustments you make are applied only to the targeted area. This is where you need to be careful with how the adjustments are applied, watching edges for halos, hardness, or aberrations that prevent your changes from looking natural. 9. Make targeted color adjustments. As with lighting, some areas of your image may need a targeted color correction. You also may want to create a color effect, such as oversaturating areas of your photo or creating a black and white photo with color accents. 10. Add Filters or Layer styles to create artistic effects. Now that your image is put together and the lighting and color are just right, you can add Layer styles and/or Filters to create amazing images to your heart’s content. You can add these effects to your entire image or to targeted areas. These changes dramatically alter the pixels in an image or selected areas, so again watch your edges. 11. Reduce noise and sharpen your image. Because each previous change can create noise and distort sharpness to further decrease image quality, these changes should be the last you make. 12. Prepare your image for output. Whether you are preparing it to be printed or exported to the Web, you want to adjust your color settings accordingly and save your image in the correct format. Making Auto Adjustments Before you get into making your own adjustments, you should know that Photoshop makes several adjustments for you. These are great for quick fixes on photos that you don’t want or need to spend lots of time on or to get a start on. While you are new to Photoshop, they are a great way to get started on your own adjustments. Three auto adjustments are available in the Image menu: Auto Tone, Auto Contrast, and Auto Color. Auto buttons also are available in the Levels, Curves, or Black and White dialog boxes. An auto adjustment is an algorithm that uses the brightness values in an image to take a best guess at the adjustment you are applying. Although auto adjustments are frequently better than the origi- nal image, they are hardly ever the best possible settings to use. You can customize the way that the auto color corrections are applied to your image for the best results. With the Alt or Option key held down, the Auto button in either the Levels or Curves panel in the Adjustments panel transforms to the Options button. Press it to open the Auto Color Corrections Options dialog box, as shown in Figure 12.1. 19_584743-ch12.indd 37119_584743-ch12.indd 371 5/3/10 10:33 AM5/3/10 10:33 AM Part IV: Enhancing, Correcting, and Retouching 372 FIGURE 12.1 The Auto Color Corrections Options dialog box Photoshop can use three algorithms when making auto adjustments. These algorithms correspond to the Auto adjustments found in the Image menu. The Levels and Curves adjustment can use any one of the three, and you set which one here. These are your options: l Enhance Monochromatic Contrast: This is the algorithm used to set the Auto Contrast. It enhances shadows and highlights by increasing the contrast in the midtones of an image, clipping the color channels uniformly. This preserves the color integrity, but although it won’t introduce a color cast, it won’t remove one either, an important element of both the Levels and Curves adjustments. l Enhance per Channel Contrast: This algorithm is used by the Auto Tone adjustment. It finds the lightest and darkest areas of each color channel and adjusts them individually to create the most contrast of the three algorithms. Although this adjustment may introduce color casts or even fringing, this is the optimal setting in most cases for Levels or Curves because it adjusts the lighting balance of each color channel. l Find Dark and Light Colors: This algorithm is used by the Auto Color adjustment and uses an average of the darkest and lightest pixels in your image to create contrast with the least amount of clipping. The Auto Color adjustment uses the Snap Neutral Midtones to find colors that are close to neutral and changes their values so they are indeed neutral, shifting the values in the entire image to match. Note A neutral color is easy to find or create with RGB values. Each of the three values is identical. n You also can set the target colors that determine what colors are considered highlights, midtones, and shadows. The defaults here of .1 percent are on the high side if you are working with images that have been scanned or taken at high resolution with modern equipment. 19_584743-ch12.indd 37219_584743-ch12.indd 372 5/3/10 10:33 AM5/3/10 10:33 AM Chapter 12: Adjustment Workflow 373 The bottom line here is that you can use the Auto adjustments for a quick fix that might actually work if you take the time to figure out which setting is best with each individual image. Does this sound like too much work for something that was supposed to be easy? I think so too. Stick to cus- tom adjustments; you’ll have less to remember, and your images will look better in the long run. Using the Adjustments Panel The Adjustments panel is your one-stop shop to quickly click an adjustment layer over your image. I’ve already introduced you to the icon in the Layers panel that allows you to add a fill or adjustment layer—the half-black, half-white circle. The Adjustment panel is accessed with the same icon, as shown in Figure 12.2. FIGURE 12.2 The Adjustments panel Adjustment name Adjustment icons Adjustment panel icon Return to controls for current adjustment layer New adjustments affect all layers or clip to layer below Expand adjustment panel 19_584743-ch12.indd 37319_584743-ch12.indd 373 5/3/10 10:33 AM5/3/10 10:33 AM . Part IV Enhancing, Correcting, and Retouching IN THIS PART Chapter 12 Adjustment Workflow Chapter 13 Lighting and Color Adjustments Chapter. non-destructive changes to them, and then save them or open them in Photoshop. Follow the same workflow in Camera Raw as in Photoshop to create your edits. Note If you open a JPEG in Camera Raw. non-destructive. After you save your changes to a JPEG file, they become part of the image and you cannot reverse them. n 2. Open your image in Photoshop. Whether you are coming from Bridge, Camera Raw,