Photoshop cs5 cho nhiếp ảnh gia part 52 doc

320 c h a p t e r 8: COMPOSITES ■ Try It! Open the images from www.sybex.com/go/photoshopnature called HDR1, HDR2, and HDR3, and experiment with creating a 32-bit file and then converting it back to a 16-bit file. Extending the Depth of Field Nature photographers sometimes encounter situations where we want to maximize our depth of field (the range of apparently sharp focus within an image) but we encounter technical limitations. Perhaps the range we want to be in focus is too great for the lens, or the wind is blowing, so we have to use a relatively fast shutter speed to freeze the motion. Using the faster shutter speed may mean we can’t use as small an aperture as we’d like for a correct exposure without resorting to higher ISOs, which can lead to problems with noise. The solution is to take several shots with limited, but different, areas in focus and then combine them. Although you could opt to manually combine images by layering them and using layer masks, both Photoshop and Elements offer tools to automatically select the sharpest areas from each image and combine them into a single image. We’ll cover the Photoshop method first since it differs significantly from the Elements method. In Photoshop CS5 we’ll take advantage of a script to load the images into a sin- gle file and then have Photoshop automatically create the sharpest image possible by using advanced blending algorithms to choose the sharpest areas in a series of images and composite them automatically. It’s really quite impressive! To use this function, first take a series of shots with your camera on a tripod. Vary only the focus point. Begin at one extreme and slowly move the focus point back until the last area you want to be in focus is sharp. The more perfectly your images are aligned with no subject or camera movement, the better this method will work. Use your depth-of-field preview button, if you have one, to see what areas will be in focus and allow for overlap between the shots. Be careful to not change the exposure; only change the focus. 1. In Photoshop, choose File > Scripts > Load Files into Stack, or in Bridge select the images and choose Tools > Photoshop > Load Files into Photoshop Layers. Although you can opt to align the images in this step (and most of the time we do), you’ll have fewer alignment choices than if you wait and align then in a separate process, as described in Step 2. Do not choose the option to create a Smart Object, because you’ll need the layers intact. 2. If you did not align the layers in the previous step, select all layers and choose Edit > Auto-Align Layers > Auto or whichever method you prefer. 607343c08.indd 320 4/11/10 11:06:48 PM 321 ■ EXTENDING THE DEPTH OF FIELD 3. With all layers selected, choose Edit > Auto-Blend Layers > Stack Images and check the option for Seamless Tones and Colors. Click OK, and Photoshop will select the sharpest part of each image to create the final version, as shown in Figure 8.15. Figure 8.15 Using the Auto-Blend tool makes it possible to combine several images with very limited depth of eld to create a ower that has signicant detail, with a very soft out-of-focus background. Ph ot o b y EllE n An o n This feature can be very handy, and the more perfect the initial alignment of the images, the better the results. Ellen created the image in Figure 8.16 as an example of creative use of depth of field. She combined two shots, each of which used a shallow depth of field, to capture just a single water droplet in sharp focus. The result was an image with two sharp water droplets and much of the rest of the flower out of focus. This forces the viewer to concentrate on the water droplets. 607343c08.indd 321 4/11/10 11:06:49 PM 322 c h a p t e r 8: COMPOSITES ■ Figure 8.16 By compositing numerous shots with dierent focal points you can control what’s in and out of focus in an image. Ph o t o b y EllE n An o n For Photoshop Elements Users: Other Ways of Merging Images Elements users have other options to easily combine certain types of images: Photomerge Group Shot, Faces, and Scene Cleaner. Using Photomerge Group Shot to Extend Depth of Field Group Shot was designed to help when you’re taking a photo of a group, and one person has his eyes shut in one shot while another person has a weird look on her face in the next shot. Group Shot will let you load all of your shots at once, use rough lines to select areas you want, and automatically combine the images. Nature photographers can use Group Shot to extend the depth of field in an image, whether we want to combine shots of animals or combine images with different focus points. 1. Open the images you want to combine, select them all in the Project Bin at the bottom of the screen, and choose File > New > Photomerge Group Shot. Alternatively, select the images in Bridge or Organizer. Then, in Bridge go to Tools > Photoshop Elements > Pho- tomerge > Group Shot or in Organizer go to File > New > Photomerge > Group Shot. 2. Select the image that you want to use as the base Final image. You will combine parts of other images onto this image. Drag the base image onto the right side of the screen, onto the box marked Final, as seen in the following image. Continues 607343c08.indd 322 4/11/10 11:06:50 PM 323 ■ EXTENDING THE DEPTH OF FIELD For Photoshop Elements Users: Other Ways of Merging Images (Continued) Ph o t o b y Jo s h An o n 3. Select the next image from the Project Bin so that it appears on the Source box. 4. Even if you think the images are aligned, it’s a good idea to expand the Advanced Options area and select the Alignment tool, as shown here. This tool will have you place three markers on matching areas of the Source and Final images to precisely align them. 5. Check the option for Pixel Blending to blend the colors and tonalities of the image segments. 6. Click the Pencil tool to make it active, and draw on the part of the Source image that you want to merge onto the Final image. Use the Brush Size options in the upper left along with the Zoom and Hand tools to create precise strokes when needed. You can make a rough outline of an area, or on small areas just make a mark across the area. 7. Check the Show Regions option after each stroke to make certain that Elements is loading the area you want. Use the Eraser tool to remove part of your pencil lines to fine-tune any of the regions. 8. Select the next image in the Project Bin and repeat Step 3. Repeat with each image until you’ve created your composite image. Continues 607343c08.indd 323 4/11/10 11:06:52 PM 324 c h a p t e r 8: COMPOSITES ■ For Photoshop Elements Users: Other Ways of Merging Images (Continued) 9. Once you have gone through all of your images, you will see results similar to those in the following image. When you are pleased with the results, click the Done button. Elements will create a new file with the combined images. If you are combining shots with different focus points, you might need to crop the resulting image. 10. Proceed as normal through your workflow. Combining Multiple Similar Photos with Elements Elements 8 has two additional Photomerge tools, Faces and Scene Cleaner. You access these tools just like you do the other Photomerge commands, either via Bridge > Tools > Photoshop Elements > Photomerge Scene Cleaner, via Organizer > File > New > Photomerge Scene Cleaner, or via Elements > File > New > Photomerge. Use Photomerge Faces to combine multiple images of the same face (for instance, the smile from one photo and the twinkling eyes from another) or to combine elements from different faces to create a new, composite face. (The latter is useful if you didn’t obtain a model release for the main image). We’re not going to cover Faces in depth since nature photographers won’t use it often, but the main trick is to place three alignment markers on each photo, one on each eye and one on the mouth, and then click Align Photos. Photomerge Scene Cleaner enables you to combine similar shots, selecting which elements of each shot you want. For example, if you’ve ever tried to take a wide-angle photo in a crowded area at a national park, Scene Cleaner will let you combine multiple images with people in dif- ferent locations into a single clean image with no people. You could also use Scene Cleaner to combine images with different depth of field or different exposures. In the image shown here, we’re combining two images taken at different shutter speeds. Although the blurred water is nice, there was an area where the faster shutter speed revealed a colorful leaf underneath that we wanted to show in the final image. The process to use Scene Cleaner is the same as we described for using Photomerge Group Shot. Continues 607343c08.indd 324 4/11/10 11:06:53 PM 325 ■ COMBINING ELEMENTS FROM MULTIPLE PICTURES For Photoshop Elements Users: Other Ways of Merging Images (Continued) Ph o t o b y Jo s h An o n Try It! Open the images called DOF1 and DOF2 from www.sybex.com/go/photoshopnature, and practice combining them. Combining Elements from Multiple Pictures When you start combining elements from various pictures, you begin to be more cre- ative with your images. Ethically, it’s important to acknowledge that what you’re pre- senting is not a documentary photograph but rather a photo illustration or photo art. That doesn’t make it inherently more or less valuable than a straight photograph— just different. Often, a photo illustration can convey the essence or spirit of a place better than a single straight photograph. But creating something that didn’t exist and claiming it is not a manipulated photograph creates trouble for all photographers. The image in Figure 8.17 has impact, but it’s a composite and needs to be presented as such. It’s essential to make good selections when creating composites. We’ll cover some advanced selection techniques here and then show you how to put your selec- tions to work to create a variety of composites. 607343c08.indd 325 4/11/10 11:06:53 PM . change the focus. 1. In Photoshop, choose File > Scripts > Load Files into Stack, or in Bridge select the images and choose Tools > Photoshop > Load Files into Photoshop Layers. Although. differs significantly from the Elements method. In Photoshop CS5 we’ll take advantage of a script to load the images into a sin- gle file and then have Photoshop automatically create the sharpest image. using layer masks, both Photoshop and Elements offer tools to automatically select the sharpest areas from each image and combine them into a single image. We’ll cover the Photoshop method first