Feb. 3, 2011, 4:08 a.m.
posted by zloy
Understanding Camera Raw's Tabs
Camera Raw's functions are divided into tabs that were originally organized in order of workflow. However, when CS2 added new tabs, it simply added them sequentially. The most significant addition is the Curve tab, which should be used immediately after the Adjust tab. The sections below describe the features and functionality of each tab. They also discuss how workflow should be applied to each feature whenever that's a consideration.
Using the Adjust Tab Settings
The next step is to work with the settings on the Adjust tab (Figure). The settings on this tab are the most important and critical in Camera Raw. The one exception to using the Adjust Tab settings are situations in which you have already used the Calibrate tab to calibrate your camera, but because that is less commonplace and a bit more advanced we'll save the Calibrate settings for later (see "Using the Calibrate Tab"). Now, having said all that, let's just jump right in.
Figure. The Camera Raw Adjust tab, with the Auto boxes checked (on)is the default. If you wish to change an Auto adjustment,just drag the appropriate slider.
Adjusting white balance
White balance is a synonym for overall color balance. There are times when accurate white balance is absolutely critical and other times when color balance is purely subjective. White balance is critical if your assignment calls for absolutely accurate reproduction of a color in the photo. This might be the case if you were photographing a company logo or catalog items that came in a selection of specific colors.
Whether or not you get that color absolutely accurately in the final output is dependent on much more than how precisely you set white balance in Camera Raw. You'll have to begin by having your monitor accurately calibrated. Otherwise, you will have no way to judge if your white balance settings are accurate when compared to the colors on the card.
Right now, we're focused on starting with accurate color rendition in the "color negative," which is the result of the Camera Raw output to Photoshop. The best and easiest way to do that is to shoot the first image of a series in a given set of conditions (camera, lens, light source, and nearby reflective surfaces) by placing an object that contains several levels of gray and all the primary and complementary colors (Figure). Color cards must have absolutely accurate colors and gray levels, so purchase them from a reputable professional camera store. Color cards range in price from $30 to about $300. Oh, and if you're trying to match the color of a label, logo, fabric, or paint, it helps to have a sample of the actual item right alongside your monitor.
Figure. The Digital Gray Card.
Whichever card you use, place it at the same level and lighting conditions as the main subject in the first shot in a series of similar shots. Do it again any time lighting conditions change. If you're shooting sports or news, just place one in a test shot as the first shot on each memory card.
Now, here's the easiest way to get close-to-perfect color balance:
Here's a little secret: you didn't need the colors in the color card to set white balance. However, you will need them when it comes time to set camera/sensor calibration to match a specific color in the image, such as that of the blouse in the catalog ad. The best reason to get a color card is to avoid having to carry two cards.
Save the settings for each lighting condition you have measured with a gray card. That way, if you don't have the time or opportunity to place the gray card, you can look for the same conditions on your list and set the white balance to those conditions. Pretty clever, eh? Here's the step-by-step process on how to do this:
Now, here's another little secret: even if you don't have a gray card, using the White Balance Tool (the gray eyedropper icon in the Toolbar) on anything in the picture that's close to medium gray will get you surprisingly close to accurate color balance. In fact, you'll often be startled how much better the image looks than setting the white balance by simply dragging the sliders.
Which brings us to the matter of setting white balance subjectively. If your objective is to set a mood or convey emotion, rather than absolute objectivity in rendering the subject, using the White Balance sliders is totally intuitive.
Figure shows a model's face as it looked when shot in the camera and then after a subjective adjustment of the Temperature and Tint sliders.
Figure. A model's face as the camera saw the color balance (left) and the same pose after subjectively using the Temperature and Tint sliders.
To subjectively adjust Temperature and Tint, open the RAW image by double-clicking it in Bridge. It will open in Camera Raw. To give the image a warmer tone, drag the Temperature slider to the right. You'll notice the overall cast of the image becomes more yellowish-orange. If you want more of a nighttime look, drag the slider to the left and watch the image get "cooler" until it turns blue.
If your light source was fluorescent or if there were colors other than those of the main light source being reflected off nearby objects, you may have trouble getting exactly the color balance you want by using the Temperature slider alone. Fluorescent lighting has more green than conventional tungsten, daylight, or strobe. Drag the Tint to the right to reduce the green and add magenta.
The time of the day and the weather conditions you shoot in can also give you clues as to the most believable color balance. You can use the choices in the White Balance pop-up menu to automatically set the sliders to the settings typical of those conditions if you know what they were. Then, if you don't like the results, you can always further adjust the sliders to get the "feel" you want.
Adjusting exposure values
The balance of the sliders in the Adjust tab are for adjusting exposure, shadows, brightness, contrast, and saturation values of the image. The first thing you should do is set a black and white point for the image. This is done much the same way as if you were working with the Level command in Photoshop. Here are the recommended steps:
There are times when it's OK to block highlights and shadows to create a certain effect. But be sure that's the case and that you're not accidentally "uglifying" your hard work.
At this point, the image is adjusted so that, technically, it will display a full range of brightness values. If the overall image looks a bit too bright or too dark, adjust the Brightness slider. This slider adjusts the midtones. Make sure not to overdo it to the extent that blocked color blotches start to appear. If they do, either back off on the Brightness or move the Highlight and Shadow sliders as necessary to make the compensation.
Now you've got your basic exposure nailed. If you feel the image needs a bit more or less contrast, you can play with the Contrast slider. You can (and probably should) finalize contrast with the Curve tab (see the "Using the Curve Tab" section next), which will give you more control over the amount of contrast assigned to a given brightness range in the image. Using the Contrast slider is simply a matter of adjusting it to suit your visual preferences. Remember to leave all three Preview boxes checked so you can tell if your contrast adjustments start blocking highlights and shadows.
Using the Curve Tab
The next tab in the workflow is the one that goes out of order. The Curve tab's workspace is too large to fit within the Adjust tab, so it has to have its own tabeven though you're still adjusting. It really should have been positioned right after the Adjustment tab, but it's brand new, so it was simply tacked on near the end. You can see the Curve tab in Figure.
Figure. The Curve tab.
The Curve tab is just a simplified version of the Curves command in Photoshop's Image menu or in the Curves adjustment layer. There are some important differences:
So if the Curve tab isn't quite as powerful as the (nearly) equivalent command in Photoshop, why not wait until the image is in Photoshop? Well, there are actually several reasons:
There are many ways you can construct a curve. The most basic curve is a linear curve (so called because it is simply a straight diagonal line from one corner of the Histogram to the other). By default, the Tone Curve menu is set at Medium Contrast. I find that I have more control over the tonalities that I want to see by choosing Linear and then performing the following steps to adjust the curve (if you have a lot of experience with curves, you might want to skip the first two steps):
Using the Detail Tab Settings
Many experts recommend using Photoshop to correct issues instead of using the Detail tab. If your goal is maximum image quality no matter how long it takes, follow that advice by all means. On the other hand, if you often find yourself in high-pressured situations, it's a great advantage to do your initial sharpening and sensor noise cleanup before you send it out of Camera Raw and straight to your client.
The Detail tab is immediately to the right of the Adjust tab. It is used to control sharpening and sensor noise (see Figure).
Figure. The Detail tab.
The Sharpeness slider is meant to be intuitive and interactive. However, you should be very careful to avoid over-sharpening, especially if you plan to do the Effects and Output sharpening that a good "workflow for perfection" calls for. That's because sharpening sharpens sharpening. The result is overly contrasting edges and (worst case) added black shadow outlines and white halo outlines.
To avoid over-sharpening, sharpen at normal size in the Preview window. Then, before you save the image, double-click the Zoom tool so you can see a 100 percent preview. If you see even the hint of sharpening artifacts, back down on the sharpness slider.
Eliminating sensor noise
Sensor noise is something you're most likely to encounter if:
Like Sharpening, eliminating sensor noise is something that can be done as well as or better once the image is saved to Photoshop CS2. However, if you only have enough time to process your image in Camera Raw before using the Image Processor to convert your files into TIF or JPEG to ship to your client, then Camera Raw's ability to clean up any sensor noise is better than none. And, once again, if you have the time later, you can always return to the RAW file and output an image in which you've turned off Luminance Smoothing and Color Noise Reduction.
The amount and characteristics of noise that you get in your images will vary greatly. First, every camera model is different. Second, the smaller the sensor, the more likely you are to encounter noise. If you have an APS or larger size sensor, there will likely be no camera noise except at settings above ISO 400. In fact, some full-frame CMOS cameras and Foveon sensors may have no noise except when shooting very long exposures in the dark.
If the noise problem for a given image is extreme, you may just have to live with what you can reduce it to or buy a third-party noise filter such as Noise Ninja or Neat Image. The best you can do in Camera Raw is to do the best you can. More often than not, that will be enough. To find and reduce the noise that may be in an image, follow these steps:
Using the Lens Tab Settings
Figure. The Lens tab.
These settings follow the same workflow advice as I gave earlier: if your goal is maximum image quality, no matter how long it takes, rely on the power of Photoshop. If you need a quick turnaround, it's best to make the photo look as good as possible before you send it out of Camera Raw and straight to your client.
We'll work with the settings for eliminating vignetting first just because they're dead simple and also because they can be used to create vignettes as well.
Vignettes are often the result of cheap optics or of the use of filters or lens hoods that are too small to cover the entire angle of view of the lens. They tend to show up more in wide-angle opticseven more so if you have a camera with a full 35mm-size sensor. In extreme cases, you can spot vignetting when you see a gradual darkening around the edges of the photo. In Figure, I have intentionally exaggerated the vignetting to make it easier to see what it looks like.
Figure. Noticeable vignetting caused by a fully zoomed out wide-angle lens. On the right, it has been corrected by the Lens tab's Vignette slider.
There are, by the way, two types of vignettes: dark-edged and light-edged. Moving the slider to the right makes the vignette lighter; moving it to the left makes it darker. If it's dead center (the default position), the slider has no effect at all.
If you have never corrected your edges for vignettingprobably because you didn't think it existedtake a few of your widest angle photos and try correcting them by dragging the vignette slider slightly to the right. If the corners brighten just enough that the whole image looks more "even," your lens probably has a slight amount of vignetting. The chances are particularly good if the lens is a 28mm or wider 35mm equivalent and has not been stopped down more than one or two f-stops.
Now, here's the interesting part: you may want to use this slider to create a vignette. After all, vignettes can be very effective in focusing viewer attention on the center of the image. Usually, I recommend doing that on a masked adjustment layer in Photoshop so you can turn the layer on and off to show your client (or yourself) the difference. However, if you want to save a layer and still do it nondestructively, here's your big chance.
When you're correcting a vignette, you usually want to keep it centered in the frame. However, when you're creating one, you may want to be able to control the location of the center. However, you can't do that until you create the vignette itself. To make the vignette darker, drag the slider to the left. To make it lighter, drag it to the right.
Now you can move the center up or down. Simply drag the bottom slider and watch the vignette move until the vignette is positioned as you'd like it. You can see the result in Figure.
Figure. The result of creating a vignette.
Minimizing color fringing
Color fringing (aka chromatic aberration) comes in two flavors: Red/Cyan and Blue/Yellow (see Figure). Camera Raw, once again, isn't the most sophisticated tool on the planet for getting rid of this "fringe," but it's handy, nondestructive, and quick.
Figure. Red/Cyan (left) and Blue/Yellow (right) color fringing is easiest to spot along high-contrast edges.
Once again, color fringing is a phenomenon you're most likely to see with small sensors, high ISO settings, and cheap optical construction. So if you can afford the best shooting gear, you won't encounter it much. If you do, here are the steps to get rid of it:
Using the Calibrate Tab Settings
Camera Raw in CS2 has another new tab, Calibrate (Figure), which allows you to adjust the way your camera's sensor interprets color. You can adjust the color tint of shadows to make them more neutral by changing the green or magenta. You can also adjust how the sensor interprets each of the primary colors in respect to Hue and Saturation. You'll also learn to save those settings to reuse later or use on other images.
One of the beauties of RAW file processing is that, for most purposes, you don't really need to calibrate your camera. This is because you have so much flexibility in interpreting the image in Camera Raw that the exact interpretation of the image can cover a huge range. The exception is situations in which you are shooting a product or scientific assignment in which a specific color must be reproduced exactly (e.g., the color and shade of clothing in fashion advertising or company logos when in a prominent portion of the photograph).
Before someone protests, it is true that Camera Raw is powerful enough to let you match colors without calibrating your camera. If your monitor has been calibrated to a very precise level, you could simply match colors by placing the object next to the monitor and then making adjustments in Camera Raw to match the color of the object. That's a good thing, because there will be timessuch as when the client sends you a RAW file that you didn't shootwhen you have no other alternative. It is desirable, however, to calibrate your camera because it can save you hours of Camera Raw time. Besides, the more accurate your original exposure, the more latitude you have in interpreting that shot.
I've already mentioned using gray cards and color cards. If you're using only a gray card, don't expect your calibration to be good enough to accurately reproduce specific subject colors. However, your image will represent reality much more accurately and I'd advise saving the profile if you are likely to find yourself in that situation again.
The tools you use to calibrate your camera sensor are in the Calibrate tab. These happen to be the same tools you'd use to subjectively change your camera's interpretation of color and detail. I'll give you procedures for using the Calibrate tab for both purposes.
To use the Calibrate tab to subjectively tweak the interpretation of individual primary colors:
If you want to create a calibration for a particular camera and lens combination for use under particular lighting conditions, you must first take a picture in circumstances that are likely to be used in the same lighting conditions. For purposes of this example, you should shoot indoors using tungsten bulbs. Make sure there is no outside daylight coming in and that the tungsten bulbs are all of the same type. Don't mix traditional-type tungsten with the energy-saving fluorescent that has become so popularthey are likely to have very different color temperatures. Set up your shot with a white background. Figure shows how each of these should be set up.
Figure. A diagram of how your first camera calibration shot should be set up.
Here's how you use this setup to calibrate your camera for this lighting situation. If you use the color card in most of your other shooting at the beginning of any series, you will be able to check against the color card to calibrate the settings for this situation. Use the camera's information as recorded to metadata to note the time of day, year, lens, and camera. Looking at the picture itself will generally tell you about the conditions in which the photo was shot. So figure out how to incorporate all that information into a filename for the setting and save it. Of course, it will help if you know how to save calibration settings so you can apply them to any other RAW file. If that RAW file was shot in the same conditions, your rendition should be technically perfect, especially to ensure the accuracy of colors. I'll go over saving calibration settings next. Here's how you shoot the test shot to calibrate colors accurately for controlled tungsten lighting on a white background:
Making situational calibrations
Situational calibrations are made in conditions that you commonly encounter when shooting. Just be sure to have your color card in your camera case. When you arrive on the scene to shoot a situation, place the color card into the scene where it can be plainly seen and shares the same lighting as the subject you'll be shooting. When you're back at the computer, calibrate the shot you took and give it a name that can apply to similar situations when you don't have time to insert the color card in the shot. Then, when you're calibrating your shoot, you can just look for a settings title that matches the situation and apply that calibration to the new photos taken in the same condition.
Saving and retrieving settings
Saving calibration settings is no different from saving any or all of the other settings. The one difference is that when saving setting for calibration purposes, you should return all the other settings for all the other tabs to their default settings.
Then, follow these steps to save the settings:
Applying calibration settings to a collection
You can apply calibration settings to a whole series of images by opening them at the same time in Camera Raw. If you have more than, say, 16 images (the exact number depends on your installed RAM and on the size of the images), you may have to repeat these instructions for additional batches:
What if you have several hundred shots that you need to add the calibration settings to before you adjust the settings? Easy. Open one of those files in Camera Raw, apply the calibration settings and then click the Done button. Now, go back to Bridge, select all your files and then, in Bridge, choose EditPrevious Conversion. You may have to drum your fingers for a few seconds, but all those images will have the calibration settings applied to them.
As you can see, it is possible to have dozens of calibrations for different lens, camera, and lighting situations.