Professional Information Technology-Programming Book part 25 pps

6.2. Adjustment Layer Advantages You probably already understand this, but an adjustment layer actually doesn't make any changes to the layers below it. It simply gives Photoshop CS2 instructions on how the image should look and print. Adjustment layers have the further advantage of being readjustable at any time, as long as you haven't merged or flattened their layers (which you should only do when you duplicate the image and flatten it to purposely send an unmodifiable version to someone outside your company or personal domain). If you're not yet familiar with adjustment layers, you'll find them listed on a menu that appears after clicking the New Adjustment Layer icon at the bottom of the Layers palette or by choosing Layer New Adjustment Layer. The adjustment commands that are available on adjustment layers use exactly the same dialog as their Image Adjustments menu counterparts. So if you know how to adjust without an adjustment layer, you also know how to adjust with one.Table 6-1 shows the specific adjustments that are available as adjustment layers. Table 6-1. Table 6-1. Available adjustment layer options Levels Hue/Saturation Photo Filter Curves Selective Color Invert Color Balance Channel Mixer Threshold Brightness/Contrast Gradient Map Posterize The adjustments in Table 6-2 are available only as destructive adjustments, which I'll show you how to apply in a nondestructive way in Chapter 11. Table 6-2. Table 6-2. Available destructive adjustments Auto Levels Match Color Equalize Auto Contrast Replace Color Threshold Auto Color Shadow/Highlight Variations Table 6-2. Table 6-2. Available destructive adjustments Auto Levels Match Color Equalize Desaturate Exposure NOTE All of the routines in this section assume that you have run the basic Workflow Layers Action described in the "The Magic Action for Layered Workflow" section in Chapter 5. If you skipped that chapter, jump back before going on. What follows is an example of how each adjustment layer type might be particularly useful in a circumstance commonly encountered by professional photographers (remember, you don't have to be a pro to learn how to think like one). Whereas Chapter 5 described each layer's function, this chapter gives you the most practical applications for each adjustment layer. And this time, the layers are more or less in order of frequency of use. I say more or less because no two photographers' requirements are exactly the same. In fact, some of these commands may never be a part of your style. Still, it's good to know what your options are. 6.2.1. Levels Adjustment Levels is the best command for ensuring that you have a full range of tones in your image. However, I have to give you a bit of a warning here: a maximum range of tones is not always best suited for every purpose. I have known photographers to make a career of styling their photos to have a unique look by forcing a very limited range of colors. On the other hand, the best artists are usually trained to create technically perfect art, so they know exactly why they are deviating. End of lecture. The Levels command is also often used for setting white balance. There are a couple commonly used ways that should definitely be a part of your routine. 6.2.1.1. Setting technically correct white balance You will need some part of the photo to be absolutely neutral in color. A grayscale card, black tires, or bleached coffee filters are all good candidates. These have to be the real colors of the neutral object. Don't try using a Photoshop technique to make them that colorit won't work. Figure 6-6 shows the difference between the original image and the way it looks after this process. Figure 6-6. The image as it was when opened and then after correcting white balance in Levels using the White Balance Eyedropperfirst on the coffee filter to set white balance, then on the gray card to set exposure. Applying Adjustment Layers to Multiple Images Since all of the adjustments in this chapter are targeted at all the image layers below the adjustment layer(s), you can easily apply these adjustments to multiple images. Prepare the first image in the series. Then, open half a dozen or so of the other images in the series at the same time by selecting them in Bridge and double-clicking. If they are Camera Raw files, I'm assuming that you've already followed the instructions for applying the same Camera Raw adjustments to all the images in the series (see the "Tweaking Camera Raw Adjustments in Sync" section in Chapter 4). I'll show you the routine for applying the Levels and Curves layers that are created by the Workflow Layers Action. If you've also created others for a particular group of images, just include them in the same Layers group. Follow these instructions for applying adjustments to the series of images you want to adjust: 1. Group all the adjusted layers into an Overall Adjustments Group. 2. Open as many other images in the series as Photoshop can handle, given the configuration of your computer and memory. You should be able to open at least six at a time. 3. Keep the image you first adjusted and its Layers palette visible. Drag the other images into a stack on the right side of your screen. 4. Select the first image to make it active, and drag the Overall Adjustments Group onto the image at the top of the stack on the right. If you kept the Layers palette visible, you'll see the group appear in that image's palette, and the appearance of the image will instantly change to match the adjustment of the first image. 5. Click the Minimize Icon for the image you just dragged the Group to so that it will be temporarily out of the way. 6. Click the first image to activate its Layers palette, and drag that same group to the next image at the top of the stack. Repeat Steps 6 and 7 until all the images (other than the first one) have had the Overall Adjustments Group added to their Layers palettes. 7. Maximize the images one at a time that you added the Group to, press Cmd/Ctrl-S to save it, and then click its Close icon. Don't close the first adjusted image until you apply the Group to any of the other images in the same series that haven't been opened yet. 8. Open another six or so images and repeat Steps 48, if there are more images in the series. NOTE If you already set white balance properly in Camera Raw, you don't need to do this. Follow these steps: 1. Select the Levels adjustment layer. (If you grouped it, you'll have to open the Group to select it. To open the Group, click the small gray arrow to the left of the Group folder in the Layers palette.) 2. Double-click the Levels icon. 3. Choose the Set Gray Point dropper and click on the neutral-tone object. I have to tell you one more time: the "neutral tone" had really better be totally lacking in color tint and be absolute gray, regardless how light or dark. Otherwise, your white balance will be surprisingly incorrect, rather than correct. 4. Adjust the midtone slider to the appropriate brightness level, if necessary. If you didn't have time to include a gray or color card and there is nothing in the image that is absolutely neutral, there's still a process that ensures you have maximum brightness range from each color channel, as well as overall brightness range. The result is usually surprisingly good color balance and a much richer image than you might otherwise have expected. All of which make it a good idea to use this process on any image that you haven't been able to color balance with a gray or color card. Figure 6-7 shows the before and after result of applying this process to one image. Figure 6-7. The image as it was shot and then after color correction in Levels by using each color channel. Grayscale and white cards weren't used at all to make these adjustments. Follow these steps to correct the color as shown in Figure 6-7: 1. Open the image from Bridge. If it's a RAW image, do the best you can in Camera Raw first. 2. Go to the Layers palette and double-click the Levels icon in the Overall Levels layer. The Levels dialog opens. Do not make any adjustments in the composite (RGB) channel just yet. 3. Press Cmd/Ctrl-1. You are now in the Red channel. If the Histogram "mountain" touches ground on either end before it touches the end of the base, drag the slider on that end until it touches the base. If the Histogram also touches ground before the other end, drag that slider until it touches the base. Figure 6-8 shows how the sliders should look. Do not move the midtone slider for any of the color channels at this point. Figure 6-8. The Histogram in one color channel of the Levels dialog showing the sliders adjusted as recommended. 4. Repeat the color channel adjustment you just made for the Red channel for the Green (Cmd/Ctrl-2) and Blue (Cmd/Ctrl-3) channels, in that order. 5. Make the adjustment for overall brightness and contrast. Press Cmd/Ctrl-~ (tilde) to get to the RGB channel. Adjust the Highlight and Shadow channels in the same way as you did in the previous steps. 6. Adjust the overall midtone brightness. Drag the Midtone (center) slider until you like the overall brightness of the image. Normally, this is where you're done. However, sometimes you want to make some further subjective judgments to the overall brightness range and color balance. If that's the case for the image you're currently working on: a. To change the color balance, go to the channel that contains the color you most want to change. Drag the Midtone slider to the right to intensify the primary color or to the left to intensify the complementary color. For the Red channel, the complementary color is Cyan. For the Green channel, it's Magenta. For the Blue channel, it's Yellow. b. To change overall contrast, go back to the RGB channel and spread the distance between Highlight and Shadow to lower contrast or decrease the distance between Highlight and Shadow to increase the contrast. 6.2.2. Curves Adjustment I can usually improve an image by changing the contrast within a chosen range of . follows is an example of how each adjustment layer type might be particularly useful in a circumstance commonly encountered by professional photographers (remember, you don't have to be. couple commonly used ways that should definitely be a part of your routine. 6.2.1.1. Setting technically correct white balance You will need some part of the photo to be absolutely neutral in color photographers' requirements are exactly the same. In fact, some of these commands may never be a part of your style. Still, it's good to know what your options are. 6.2.1. Levels Adjustment