Hands-On Camera Raw
Knowing what each control does in Camera Raw is only half the battle. The other half is in knowing how the various controls interact, and when (and in what order) to use them. So with these goals in mind, let's look at a simple scenario, processing individual images, one at a time, in Camera Raw.
It's useful to split the work into three phases, even though the third phase is where most of the work gets done, because if you mess up the first phase, you won't get the results you wanted, and if you skip the second phase you may miss critical issues in the image when you execute phase three. The three phases are:
- Setting up Camera Raw—Preferences and workflow settings
- Evaluating the image
- Editing the image
Let's look at these in turn.
Camera Raw Setup
The first order of business is to set up Camera Raw to make it work the way you want it to. To do that, you must open a raw image, because until you actually launch Camera Raw you can't do anything with it. Size the Camera Raw window by dragging the handle at the lower-right corner so that you can see a decent-sized image preview, with the controls conveniently placed. If most of your images are verticals, you may prefer a narrower Camera Raw window than if you mostly shoot horizontals. I like to size the Camera Raw window to fill the entire screen.
Next, make sure that Camera Raw's Preferences are set to behave the way you want them to. There's no right or wrong answer to how the Preferences should be set other than that they should produce the behavior you want. You can open Camera Raw's Preferences either by choosing Preferences from the Camera Raw menu (Camera Raw must be set to Advanced mode) or on the Mac only, by choosing Camera Raw Preferences from the Photoshop menu (the command only appears when Camera Raw is open; see Figure 3-27).
Figure 3-27 Camera Raw Preferences command
Camera Raw's Preferences are pretty straightforward. You only have two settings to worry about—where to save settings and how to apply sharpening.
Save image settings in:
controls where your image settings get saved, with two choices; "Camera Raw database" or "Sidecar ".xmp files." Each has its advantages and disadvantages.
When you save settings in the Camera Raw database, they're indexed by file content rather than name, so even if you rename the raw file, Camera Raw will associate the correct settings with the image. But if you move the image to a different computer, the settings won't be available because they're stored in the Camera Raw database on the first computer.
When you save settings as sidecar .xmp files, they're saved as separate files, in the same folder as the image, and with the same name as the image except that they take a .xmp extension instead of the extension that identifies raw files (.CRW, .NEF, and so on). The File Browser has a preference setting that automatically keeps the sidecar files with the images as long as you use the File Browser to move or copy them. You can run Batch Rename, and the sidecar files will get renamed along with the images; but if you move or copy the images outside the File Browser, it's up to you to make sure that the sidecar files go with them.
If you only use a single computer and never send your raw files to anyone else, it may make sense to store all the Camera Raw settings in the Camera Raw database, but I find that sidecar files offer more flexibility at the cost of slightly more complex file management. If you want to archive your settings along with the images when you burn them to CD or DVD, sidecar files are the only way to go.
Apply sharpening to:
controls whether sharpening applied by the Sharpness slider in the Detail tab is applied to the image preview only or to the converted image. (If you choose Preview Images Only, a label to that effect appears beside the Sharpness slider.)
I usually sharpen the image post-conversion in Photoshop, but it's often useful to apply some sharpening to the preview to aid in making decisions about contrast. So I normally leave Camera Raw's preference set to Preview Images Only. (Note that the sharpening is applied not only to Camera Raw's image preview, but also to the previews and thumbnails displayed by the File Browser.)
However, if I need to process a lot of images quickly, I'll use Camera Raw's sharpening and change the preference to apply sharpening to All Images—that way, the sharpening I set with the Sharpness slider is applied to the converted image as well as to the preview.
If either of the preferences are set incorrectly, you'll need to redo all of your work once you've set them the way you want, so always make sure that they're set the way you think they are—it will save time in the long run.
The workflow settings govern the color space, bit depth, size, and resolution of the converted image. They're called "workflow settings" because you'll typically change them to produce different types of output. For example, when you want to create JPEGs for online viewing or review, it would make sense to choose sRGB as the color space, 8-bit for bit depth, the smallest size for your camera for size, and 72 ppi for resolution. But to produce images for large prints, you'd probably switch to a wider color space, use 16-it for bit depth to accommodate further editing in Photoshop, the largest size supported for your camera, and 240 ppi for resolution.
The workflow settings are recordable in actions, so once you've learned your way around, you can easily incorporate the workflow settings you want in batch processes—I'll discuss building actions for batch processes in Chapter 7, Exploiting Automation.
Four different menus make up the workflow settings (see Figure 3-28).
Space dictates the color space of the converted image. The choices are Adobe RGB, Colormatch RGB, ProPhoto RGB, and sRGB. If you use one of these spaces as your Photoshop RGB working space, choose that space here, unless you're producing imagery for the Web, in which case you should choose sRGB.
A huge number of words have already been expended on the subject of RGB working spaces, and I don't want to add to them here—if you want to read some of mine, www.creativepro.com:80/story/feature/8582.html is a good place to start. The one practical recommendation I'll make regarding choice of working space is, use Camera Raw's histogram to detect colors being clipped by the chosen output space. If a space clips colors, look to see if they're important to you. If they are, choose a wider space. See "Evaluating Images," later in this chapter.
Depth lets you choose whether to produce an 8-bit/channel image or a 16-bit/channel one. Unless I'm creating JPEGs for Web or email use, I always convert to 16-bit/channel images, because they allow a great deal more editing headroom than 8-bit/channel ones. The inevitable trade-off is that the files are twice as large.
If you plan on doing minimal editing in Photoshop, converting to 8-bit/channel may save you some time, particularly if you run Photoshop on older, slower machines. Everyone has their own pain point! See the sidebar "The High-Bit Advantage" for more on 16-bit/channel images.
Size lets you choose one of several output sizes. The specific sizes vary from camera to camera, but they always include the camera's native resolution as well as higher and lower ones.
With cameras that produce non-square pixels, there's a clear advantage to using Camera Raw to go one size up from native—for the details, see "Size" in Chapter 2, How Camera Raw Works—but for the majority of cameras, the difference is much less clear-cut and is as much about workflow convenience as it is about image quality. See the sidebar "When to Resample" for further discussion.
- Resolution lets you set a default resolution for the image. This is purely a workflow convenience—you can always change it later using Photoshop's Image Size command. If you need 240-ppi images for inkjet printing or 72-ppi images for Web use, set that resolution here to save yourself a trip to the Image Size dialog box later.
Figure 3-28 Camera Raw workflow settings
You can't load and save workflow settings as you can image settings, but you can record workflow settings in actions that you can then use for batch processing. The workflow settings are sticky per camera model, so always check to make sure that they're set the way you need them.
Before starting to edit a raw image, it's always a good idea to do a quick evaluation. Is the image over- or underexposed? Does the subject matter fall within the camera's dynamic range, or do you have to sacrifice highlights or shadows? Camera Raw offers three features that help you evaluate the raw image and answer these questions.
- The histogram lets you judge overall exposure and detect any clipping to black, white, or a fully saturated primary.
- The image preview shows you exactly how the converted image will appear in Photoshop, and the clipping display, available when you adjust the Exposure and Shadows sliders, lets you see exactly which pixels, if any, are being clipped.
- The RGB readout lets you sample the RGB values from specific spots in the image.
If an image is too dark or too light, you need to decide whether to fix it by adjusting Exposure or Brightness. If it's too flat, you need to decide whether to increase the Contrast value or add snap to the shadows with the Shadows control. For decisions like these, Camera Raw's histogram is a useful guide.
Camera Raw's histogram is simply a bar chart that shows the relative populations of pixels at different levels. The colors in the histogram show what's going on in each channel.
White in the histogram means that this level has pixels from all three channels. Red, green, and blue mean that this level has pixels from these individual channels. Cyan means that this level has pixels from the green and blue channels, magenta means this level has pixels from the red and blue channels, while yellow means that this level has pixels from the red and green channels. (If it's easier, you can think of cyan as "no red," magenta as "no green," and yellow as "no blue.")
Spikes at either end of the histogram indicate clipping—white pixels mean that all three channels are being clipped, colored ones indicate clipping in one or two channels—see Figure 3-29.
Figure 3-29 Clipping and the histogram
The histogram can help you determine whether or not the captured scene fits within the camera's dynamic range. If there's no clipping at either the highlight or the shadow end, it clearly does. If there's clipping at both ends, it probably doesn't. If there's clipping at only one end, you may be able to rescue highlight or shadow detail (if you want to) by adjusting the Exposure slider.
The histogram also shows clipping in individual channels. Typically, clipping in one or two channels indicates one of two conditions.
- The RGB space selected in the Space menu is too small to hold the captured color. In that case, try switching to a larger space if the color is important.
- You've pushed the saturation so far that you've driven one or more channels into clipping. Again, this isn't necessarily a problem. To see exactly what's being clipped, you can use the Exposure or Shadows slider's clipping display, which I'll discuss next.
The main function of the image preview is, of course, to show you how the converted image will appear. After looking at the histogram, I usually use the white balance tool to do a quick click-balance by clicking on an area of detail white (though I'll probably fine-tune it later with the Temperature and Tint controls). However, if the histogram tells me I need to use Camera Raw's extended highlight recovery, I'll wait until I've set endpoints before attempting a white balance.
The image preview also offers a couple of indispensable tricks in the form of the highlight clipping display and shadow clipping display offered by using the Option key in conjunction with the Exposure and Shadows sliders, respectively. Hold down the Option key, and then hold down the mouse button on either slider to see the clipping display. The display updates dynamically as you move the slider, so it's also very useful for editing.
Exposure clipping display.
Holding down the Option key as you move the Exposure slider turns the image Preview into a highlight clipping display—see Figure 3-30.
Figure 3-30 Highlight clipping display
Shadows clipping display.
Holding down the Option key as you move the Shadows slider turns the image preview into a shadow clipping display—see Figure 3-31.
Figure 3-31 Shadow clipping display
While the histogram shows you whether or not clipping is taking place, the clipping displays show you which pixels are being clipped. If you want to evaluate clipping on single pixels, you'll need to zoom in to 100% view. Camera Raw does its best to show you clipping at lower zoom percentages, but it's only completely accurate at 100% or higher zoom levels.
The RGB readout lets you sample the RGB values of the pixel under the cursor. The readout always reports the average of a five-by-five sample of screen pixels. You can't sample individual pixels, though you can get close at a 400% zoom level. To sample fewer pixels, zoom in, and to sample more pixels, zoom out.
The RGB readout helps you distinguish between, for example, a yellow cast and a green one, or a magenta cast and a red one. Sample an area that should be close to neutral. If the blue value is lower than red and green, it's a yellow cast; if the green value is higher than red and blue, it's a green cast.
Figure 3-32 shows the evaluation process for several different images, with a variety of exposures. In the next section, I'll proceed with editing these images.
Figure 3-32 Evaluating images
At last, we come to the heart of the matter—editing raw images! The controls in Camera Raw are presented in a fairly logical order. I always start with the controls in the Adjust tab, followed by those in the Detail tab, and then, if necessary, those in the Lens tab. Normally, I don't make adjustments to individual images in the Calibrate tab, reserving it for fine-tuning the response of specific cameras; but on occasion, it can be a handy creative tool, too.
Using the Adjust tab controls
The Adjust tab contains the controls that let you set the overall contrast and color balance for the image—see Figure 3-33. A simple rule of thumb that has served me well over the years is to fix the biggest problem first. In the case of raw images, this always boils down to starting with either the Exposure or the White Balance controls.
Figure 3-33 The Adjust tab
If the image needs a major (more than 0.25-stop up or down) exposure adjustment, it's better to do that before setting the white balance, because the exposure adjustment will probably affect the white balance. If the image needs little or no exposure adjustment, set white balance first.
The Temperature control adjusts the color of the light for which Camera Raw is compensating in Kelvins. So as you increase the color temperature, the color balance moves towards yellow to compensate for the bluer light, and as you decrease the color temperature, the image heads toward blue to compensate for the yellower light.
The Tint control adjusts the red-to-green color balance—positive values head toward red, negative ones head toward green.
It's often easiest to start by doing a rough click-balance with the white balance tool by clicking on an area of detail white in the image. Don't click on a specular highlight unless you're going for psychedelic results! Then you can fine-tune using the Temperature and Tint sliders—see Figure 3-34.
Figure 3-34 Setting white balance
The White Balance controls are designed to reconstruct the actual white balance of the scene, but they're also amenable to creative use. You can warm or cool an image with more control and less image degradation than you can in Photoshop. Figure 3-39, later in this chapter, shows two examples.
Figure 3-39 Creative white balance
Along with the White Balance controls, the Exposure slider is possibly the most critical tool in Camera Raw—if you don't take advantage of the White Balance and Exposure tools to optimize your captures, you're essentially negating the benefits of shooting raw!
At positive values, the effects of the Exposure slider closely mimic increasing the exposure using the on-camera controls. At negative settings, its behavior depends on whether or not the image contains any completely clipped pixels—that is, pixels that are blown out to solid white in all three channels. If the image contains no completely blown pixels, the Exposure slider works very much like reducing the exposure in camera. Otherwise, Camera Raw leaves completely white pixels as white, rather than turning them gray, and stretches the highlight range to recover as much detail as possible. The amount of recoverable highlight detail varies from camera to camera—see the sidebar "How Much Highlight Detail Can I Recover?" in Chapter 2, How Camera Raw Works, for more details.
The Exposure slider affects the entire tonal range, but it's essentially a tool for setting the white point. This is a much more critical operation with digital captures than it is with film scans due to the linear-gamma nature of digital raw, which uses half of the captured bits to describe the brightest f-stop (see the sidebar "Exposure and Linear Gamma" in Chapter 1, Digital Camera Raw). Use the Exposure slider to make sure that diffuse highlights still contain detail (the RGB readout is useful for checking pixel values, while the highlight clipping display aids in adjusting the Exposure slider), without worrying overmuch about what it does to the midtones and shadows. See Figure 3-35.
Brightness and Contrast.
While the Shadows slider is presented before the Brightness and Contrast sliders in Camera Raw's user interface, it's almost always better to use the Brightness and Contrast controls to shape the overall tonality of the image and reserve the Shadows slider for fine-tuning the black point afterward. Small changes to the Shadows value often produce big changes in the image due to the linear nature of the raw image—raw captures have far fewer bits describing the shadows than they do describing the highlights.The Brightness control adjusts midtone brightness without affecting the endpoints of the tonal range, so it's generally the next adjustment you want to make. The Contrast control, at positive settings, brightens values above the midpoint set by Brightness and darkens values below that midpoint. At negative settings, it darkens values above the midpoint and brightens those below, but in both cases it leaves the endpoints alone. Due to the linear capture, Contrast has a more obvious effect on the darker three-quarter-tones than it does on the brighter values. See Figure 3-36.
Figure 3-36 Setting Brightness and Contrast
The Shadows control sets the black point. If you use the shadow clipping display obtained by holding down the Option key as you move the Shadows slider, you'll typically see big clumps of pixels being clipped with each change in the Shadows value. If you want to make big changes to the black point, you can make a Shadows adjustment immediately after adjusting Exposure and before tweaking Brightness and Contrast. But in most situations, it's best to make the other tonal moves first and reserve Shadows for fine-tuning the black point. See Figure 3-37.
Figure 3-37 Setting Shadows
The Saturation control works similarly to the master Saturation slider in Photoshop's Hue/Saturation command. I typically make small moves with the Saturation slider, preferring to fine-tune selective color ranges on the converted image in Photoshop. Due to the linear nature of raw captures, Camera Raw's Saturation control has a stronger effect on the quarter-tones than on other parts of the tonal range. If that's what you need for a particular image, use it; otherwise save the saturation moves for Photoshop.Last but not least, don't overlook the creative possibilities Camera Raw offers. Figure 3-38 shows some very different treatments of the same image.
Figure 3-38 Creative Camera Raw
The White Balance tools are also amenable to creative use. Figure 3-39 shows two examples. At default settings, Camera Raw's white balance attempts to reproduce the white balance of the actual scene, but the tools allow allow you to apply redical warming or cooling effects in a way that Photoshop just can't achieve.
Once you've made all the adjustments in the Adjust panel, it's time to move on to the Detail panel. The reason for making all the tonal adjustments first is that they can change the noise signature of the image significantly, so until you've made these adjustments, you won't have a good idea of what needs to be done in terms of noise reduction.
The Detail tab
The Detail tab contains three controls, Sharpness, Luminance Smoothing, and Color Noise Reduction—see Figure 3-40. Their effect is only visible when you zoom in to 100% view or higher, but it's usually useful to zoom to a higher percentage when working the Luminance Smoothing and Color Noise Reduction controls to really see what's happening.
The Sharpness slider lets you apply sharpening either to the preview image only or to both the preview and the converted image—see "Preferences," earlier in this chapter.
I usually apply sharpening to the preview image only—it's easier to make decisions about contrast on a reasonably sharp image than on a very soft one, so I set the Sharpness slider to a default of 25 and incorporate that in my Camera Default settings (see "Saving Settings," later in this chapter). The value isn't set in stone—you may want to choose a higher or lower value based on your camera, your display type and resolution, and your personal taste. The goal is simply to make the preview image reasonably sharp to aid editing decisions. Then I apply more controllable sharpening to the converted image in Photoshop.
However, if I'm converting a large number of images to JPEGs for review or transmission, and time is of the essence, I'll temporarily switch my Camera Raw Preferences to apply sharpening to the converted image.
- Luminance Smoothing. Luminance noise shows up as random speckled variations in tone that are usually more prominent at higher ISO speeds than at lower ones. The noise tends to be concentrated in the darker tones; it's much easier to see if you apply some sharpening to the preview image using the Sharpness slider and zoom in as far as you can go.If you see luminance noise, simply raise the value of the Luminance Smoothing slider until it goes away. (Unlike many aspects of Camera Raw, this one isn't complicated!) Luminance smoothing does soften the image somewhat, so don't apply more than you need. The default value is zero, but depending on your camera and your shooting style, you may want to increase this value slightly (6-10) and save it as a new camera default if you don't want to check each individual image. Higher ISO speeds, long exposures, or underexposing to hold highlights all tend to increase the luminance noise, so it's worth spending some time analyzing your images to determine a good default value for the Luminance Smoothing slider.
Color Noise Reduction.
Color noise usually shows up as random magenta and green splotches in dark areas, but with some cameras it can also manifest itself as colored speckles around highlights.As with luminance noise, raise the Color Noise Reduction slider value until the color noise disappears—see Figure 3-41. The order in which you apply Luminance Smoothing and Color Noise Reduction isn't critical—I tend to fix the worse of the two problems first. Color Noise Reduction has much less impact on image sharpness than does Luminance Smoothing, so it's fairly safe to leave it at the default value of 25 if you don't want to check each individual image.
Figure 3-41 Color Noise Reduction
Figure 3-40 The Detail tab
Most cameras exhibit some degree of color noise at all speeds. Luminance noise tends to be more common at high speeds, but both types of noise vary considerably from one camera model to another. The built-in defaults are a reasonable starting point, but you'll almost certainly want to tweak them and save as your own Camera Default settings. You may even want to save separate settings for different ISO speeds—see "Saving Settings," later in this chapter.
The Lens tab
The controls in the Lens tab let you address two problems, one common, the other pretty rare. If you use zoom lenses, you'll almost certainly run into chromatic aberration—color fringing along high-contrast edges caused by the inability of the lens to bring all the wavelengths of light to focus at the same plane—at some point in your work. Digital capture is extremely demanding on lenses, and it's not at all unusual for a lens that performs superbly on film to show some chromatic aberration on digital captures, particularly at the wide end of the range. Vignetting, where the corners are darkened because the lens fails to illuminate the sensor evenly, is rarer, but you may encounter it at very wide apertures. The controls in the Lens tab let you address both problems—see Figure 3-42.
- Chromatic Aberration controls. Camera Raw offers two Chromatic Aberration sliders, one to address red/cyan fringing (Chromatic Aberration R/C), the other to address blue/yellow fringing (Chromatic Aberration B/Y). They work by adjusting the size of the red and blue channel, respectively, in relation to the green channel.The adjustments have remarkably little impact on the rest of the image. Mathematical comparisons of the non-edge pixels may reveal a one- or two-level difference in one channel in a few areas; but I've yet to see a difference that could be detected visually, so don't be afraid to use these controls to eliminate color fringes. Two tips may help you do so.
Figure 3-42 The Lens tab
Figure 3-43 shows a typical example of chromatic aberration, along with the necessary fixes.
- Vignetting controls. Camera Raw offers two controls for addressing vignetting. Vignetting Amount controls the degree of darkening (negative values) or lightening (positive values) applied to the image. Vignetting Midpoint, which is enabled only when Vignetting Amount is set to a non-zero value, controls how far the correction extends from the corners.Thus far, the only example I've seen of vignetting on digital captures has been with tilt/shift lenses, and since this vignetting is asymmetrical, the controls don't help. They are, however, handy for burning in the corners of the image!
Figure 3-43 Chromatic Aberration corrections
The Calibrate tab
I've already covered the intended use of the Calibrate tab controls—fine-tuning the color rendering for a specific camera—in detail earlier in this chapter. Here I'll look at some creative uses of the controls.
One non-obvious use of the Calibrate tab, which I must credit to Adobe evangelist, raconteur, bon vivant and demomeister Russell Brown, is in color-to-grayscale conversions. Start by reducing the Saturation control in the Adjust tab to –100, and then move to the Calibrate tab. The Hue sliders control the panchromatic response, while the Saturation controls let you modulate the strength of the Hue controls' effect. Figure 3-44 shows examples of different black and white conversions, along with the settings that produced them. Note that the ideal values will vary from camera to camera, but the ones shown here should get you in the ballpark.
Figure 3-44 Color to grayscale
These conversions approximate the use of traditional color filters, but you aren't limited to this approach—you can create intermediate settings or make image-specific conversions.
If you're going for natural color, it's probably a bad idea to use the Calibrate controls as selective color correction tools—selective color corrections are better left for Photoshop—but you can certainly use them for creative color effects like the one in Figure 3-45!
Figure 3-45 Creative color with Calibrate