The Camera Raw Interface


Technically, Camera Raw is a plug-in, just like a special effects plug-in that you might install. Camera Raw's interface changes slightly depending on whether you're running it in Elements or CS2, but the underlying image processing code is the same. Some of the features that aren't there when running Camera Raw in Elements are high-end features that you probably won't miss, and that we won't be covering in this book anyway.

Camera Raw in Photoshop CS2

Camera Raw presents the dialog box shown in Figure 4.11 when you open it from Photoshop CS2 or Bridge.

Figure 4.11. When running Camera Raw 3.1 under Photoshop CS2, you see the following interface. Previous versions differ only slightly.


The Camera Raw interface is divided into five major areas. The large preview lets you zoom and pan across your image. The upper-right corner houses a histogram, and directly below are the program's main controls, which you use to configure Camera Raw to process your image. Below the preview window are some simple pop-up menus for defining the size that you want your final, processed image to be. Across the top of the window is a simple tool palette for zooming and panning, sampling colors, cropping and straightening, and rotating your image.

Camera Raw in Photoshop Elements 3 and 4

The Camera Raw interface presented by Elements 3 and 4 (Figure 4.12) is very similar to the one presented by Photoshop CS2. The main differences are the simplified tool palette, which lacks Crop and Straighten tools, and the simplified raw parameters, which omit the Lens, Curve, and Calibrate controls. Camera Raw in Elements also lacks the ability to specify a size for the final image, as well as options for different color spaces and bit depths. These deficiencies may not matter to you, depending on the nature of your work. You'll learn more about what's missing as you read the rest of this book.

Figure 4.12. Photoshop Elements 3 presents a Camera Raw interface that's almost identical to the CS2 version.


From this point forward, the screenshots are from the CS2 version of Camera Raw. In most cases, the controls that you'll see explained will be exactly the same in Elements.

Camera Raw in Photoshop CS

Photoshop CS runs a slightly older version of Camera Raw than does Elements 3 or Photoshop CS2. While the CS version is very similar to the CS2 version, it lacks a few features. First, it doesn't have any auto buttons for the Exposure, Shadows, Brightness, and Contrast sliders. It also lacks the Crop and Straighten tools of the CS2 version, and it doesn't include the ability to save directly to a file. Finally, by default, it shows only two parameter panes: Adjust and Details; you need to click the Advanced button (Figure 4.13) to reveal the Lens and Calibrate panes. The CS version lacks CS2's Curves tab, which you'll learn more about in Chapter 6.

Figure 4.13. When running Camera Raw in Photoshop CS, you must click the Advanced button to reveal the Lens and Calibrate panes.


The Camera Raw histogram

This histogram presented by Camera Raw looks a little different from the histograms displayed by Photoshop (and probably different from the histogram displayed on your camera). You've already learned that images on your computer are composed of separate color channels, usually red, green, and blue. The histograms we've looked at so far in this book have been graphs of a composite of all three color channels. The Camera Raw histogram superimposes three separate graphs: one each for the red, green, and blue channels (Figure 4.14).

Figure 4.14. Camera Raw's histogram overlaps separate graphs for each color channel to give you a more refined analysis of your image.


While a composite histogram is fine for determining whether you've over- or underexposed an image to the point of clipping the highlights or shadows, Camera Raw's histogram lets you see whether you've clipped individual color channels. As you'll see, this feature comes in handy when you start using the Exposure control.

The histogram in Camera Raw represents the image as it looks with the current Camera Raw settings applied to it. This is true even when you first open the raw file in Camera Raw.

Aside from its three-color display, the Camera Raw histogram works exactly like the histograms you've already learned about; it's simply a graph of the distribution of tones in your image, from darkest on the left to lightest on the right.

Camera Raw settings

Directly beneath the histogram, you'll find Camera Raw's main Settings pane. This is the heart of Camera Raw, and these are the controls that you'll use to specify exactly how you want your image processed. Many of these controls are similar to the Levels control that you've already learned about. We'll be exploring these controls in detail.

When running under CS2, the Settings pane is divided into five tabs (Figure 4.15):

  • The Adjust tab provides the basic exposure processing controls that you'll use on all of your raw images.

  • The Detail tab houses Camera Raw's sharpening and noise reduction tools.

  • The Lens tab contains controls for correcting chromatic aberrations (strange color fringes that can occur due to inferior lens optics or lens-sensor misalignment) as well as for fixing vignetting (the corner darkening that can occur when you use a wide-angle lens).

  • The Curve tab provides an interface for making localized contrast changes to the image. If you've ever worked with the Curves control in Photoshop, then you'll be familiar with this tool.

    NOTE

    If you're using Photoshop Elements, then you won't see tabs in the Settings area. The single group of sliders provided in Elements contains the same controls as the Adjust and Details tabs in CS2.


  • The Calibrate tab provides a mechanism for tweaking Camera Raw's colorimetric information to better match your specific camera.

Figure 4.15. In Photoshop CS2, Camera Raw presents a number of controls spread among five tabs.


Pressing the Alt (Windows) or Option (Mac) key turns the Cancel button into a Reset button, allowing you to return to default values if you've made too many changes and the result isn't what you want.

We'll be looking at the details of all of these controls throughout the rest of this book.

Workflow options

Beneath the Preview pane are a collection of simple Workflow Options pop-up menus that let you specify the size and color parameters for your final image (Figure 4.16).

Figure 4.16. Camera Raw's Workflow Options controls let you set the size, bit depth, resolution, and color space as part of your raw processing.


Raw files are created using the full pixel dimensions provided by your camera. However, if you shoot with an 8-megapixel camera but are preparing images for a web site, you probably don't want the full 3504 x 2336 collection of pixels that your camera captured. By changing the selection in the Size pop-up menu, you can tell Camera Raw to automatically downsample your image to create a smaller file. Resizing in Camera Raw (either up or down) has no advantage over resizing in Photoshop, except that it can save you some time if you're batch processing images (you'll learn more about batch processing in Chapter 5).

Similarly, just as you can set pixel dimensions, you can set the resolution that you want your target image to have. Like the Size pop-up menu, the Resolution pop-up menu simply provides a shortcut for setting resolution while converting your image, rather than having to set it later using Photoshop's Image Size dialog box.

HOW MANY DOTS? HOW CLOSE TOGETHER? UNDERSTANDING RESOLUTION

Many people are confused by the relationship between pixel dimensions and resolution. All images have fixed pixel dimensionsthese are simply the width and height of the image as measured in pixels. Resolution is the measure of how many of those pixels fit into a particular space. Resolution is usually measured in pixels per inch. So if you have an image that's 3072 x 2048 pixels (typical of what you get from a 6-megapixel camera) and you've set the resolution to 300 pixels per inch, then those pixels will be squeezed together to yield a final image size of 10.24 x 6.8 inches. If you take that same 3072 x 2048 image and specify a resolution of 100 pixels per inch, then the pixels won't be crammed together quite so closely, and your final image will measure 30.7 x 20.4 inches.

For viewing images on a computer, resolution is irrelevant, because the computer can resize the display of the image on the fly to fit it into different-size windows. When printing, however, resolution makes a big difference. If your resolution is too low, then you'll see blocky pixels and poor detail. For typical printing tasks, most inkjet printers work best with an image resized to your desired printing dimensions and with a resolution setting of 240 to 300 pixels per inch.


The Space pop-up menu lets you select the color space that you want your image mapped to. As explained in Chapter 3, your choice of color space defines what the colors recorded in your image correspond to in the real world. Most cameras allow a choice of sRGB or Adobe RGB color space, and the Camera Raw Color Space pop-up menu defaults to the color space that was assigned by your camera. If you're using Photoshop CS2, you'll be able to choose from some additional color spaces, which we'll discuss later in this chapter.

The Depth menu lets you specify whether your final image should use 8 bits per pixel or 16 bits per pixel for specifying color. As discussed in Chapter 3, a 16-bit image is capable of displaying more colors and gives you more latitude when editing. You can do a lot more to a 16-bit image before you begin to see posterization and other signs of image-data loss.




Getting Started with Camera Raw(c) How to make better pictures using Photoshop and Photoshop Elements
Getting Started with Camera Raw: How to make better pictures using Photoshop and Photoshop Elements (2nd Edition)
ISBN: 0321592131
EAN: 2147483647
Year: 2006
Pages: 76
Authors: Ben Long

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