The image looks too dark in Figure 11-13. Therefore, I lightened the overall appearance of the image by increasing the Exposure; the image is rendered lighter in value and the histogram will reflect the lighter rendering by moving to the right. As the histogram is driven to the right, pixels near the right edge reach the edge indicating that the brightest pixels will be rendered pure white. Conversely, decreasing the Exposure setting will darken the image and shift the histogram to the left.
While the Exposure slider shifts the entire histogram to the right, the Recovery slider controls the extreme highlights by allowing you to dial back the highest values. To fine tune the rendering of the extreme highlight values, move the Exposure slider to the right to increase overall exposure and then move the Recovery slider to the right to restore highlight details. Depending on the amount of exposure the highlights received, you may be able to recover detail in some or all of the highlights that appear in the camera’s histogram display to be blocked. By working the Exposure and Recovery sliders, you can adjust the appearance of the image and, if the capture is not too badly overexposed, control which, if any, pixels will be rendered pure white.
Figure 11-13. RAW capture converted with ACR default settings together with the histogram
Figure 11-14. RAW capture with Exposure (+0.9) and Recovery (67) adjustments together with the histogram
Figure 11-15. RAW capture with adjustments to Exposure (+0.9), Recovery (67), and Blacks (20) settings together with the histogram
As an aid in setting the white point, hold the Option/Alt key while moving the Exposure or the Recovery slider. The screen will appear black except for those areas that will be rendered pure white. As you move the Exposure slider to the right, more of the image will be rendered pure white and will appear on the screen. As you move the Recovery slider to the right, more of the highlights will disappear into the black screen indicating they will not be rendered pure white. Release the Option/Alt key to view the image. Again, be mindful that just because you have the control to render portions of the image as blank white, you are not required to do so and in most instances you will want only small areas of the image to be rendered pure white. Your artistic judgment should guide you in deciding which areas, if any, should be rendered pure white.
Figure 11-14 shows the result of increasing the Exposure value from the default setting of 0 to 0.9 and increasing the Recovery value from the default setting of 0 to 67 to preserve detail in the extreme highlights.
Thus far, we have addressed the lighter portions of the image; we now turn to the darker areas by setting the black point. This time move the Blacks slider to the right to render the darker portions of the image as pure black. To observe the areas that will be rendered pure black as you move the Blacks slider, hold the Option/Alt key while moving the Blacks slider. The screen will appear white except for those areas that will be rendered as pure black. Again, there is no requirement that you render large portions, or any portion, of your image pure black; use your judgment.
Figure 11-15 shows the image as adjusted with the Exposure and Recovery values used in Figure 11-14 with the Blacks value increased from the default setting of 5 to 20. Note how the darker areas of the image have been lowered in value and the overall contrast of the image has been increased. The spike at the left edge of the histogram reflects the pure black pixels in the image.
Lastly, the display of your work, whether it is backlit as on a computer display or reflective as with an inkjet print, will influence the appropriate setting of the black and white points in an image. Backlit displays will reveal details in deep shadows that would be lost in an inkjet print. Similarly, highlight tonalities will appear different depending on whether they are backlit or reflective. Indeed, prints may need to be adjusted for different viewing conditions. Observation of your work under various lighting conditions will soon give you the judgment to relate the appearance on the computer display, and the numerical data from your software’s color sampler, to your intended form of output. It will prove to be of great help to use the eyedropper tool in Photoshop as a densitometer to correlate the image on the screen to your output, and this will be particularly useful for printed output.
In practice, try all of the controls, observe the image as you change settings, and remember that you can keep changing the settings until you get the result you desire. In other words, play around with it. Toggle the triangles in the upper left and right hand corners of the histogram on and off to display any areas of underexposure and overexposure. See what you can and can’t do. Experiment. Only when you tell the program to Open Image (or Save Image) will the settings be applied and the results be saved as a converted image.
In addition to using the Exposure, Recovery, and Blacks sliders in ACR, after you convert the RAW file you can fine tune the settings in Photoshop using either a Levels or Curves layer. To illustrate using Curves, first, create a new Curves layer: From the Layer menu select New Adjustment Layer and choose Curves. Photoshop will prompt you for a name for the new layer. Insert a descriptive name such as Global Contrast, and click OK. The Curves palette will open and present both the histogram and a default straight line curve. At the lower left of the histogram is a black triangle that sets the black point of the image. Moving the black triangle to the right forces darker pixels to pure black. Hold the Option/Alt key down and slide the black triangle to view the portions of the image that will be rendered pure black. Similarly, at the lower right of the histogram is a white triangle that sets the white point of the image. Moving the white triangle to the left forces brighter pixels to pure white. Hold the Option/Alt key down and slide the white triangle to view the portions of the image that will be rendered pure black. While you have the Curves layer open, you can adjust the overall appearance of the image by altering the curve.
Correcting Aberrations
The projection of the scene through your camera lens onto the photosite-CFA induces a number of undesirable effects including color fringing, vignetting, the introduction of noise, and loss of sharpness. RAW converters have a number of tools for the correcting of aberrations. Using a high quality, calibrated monitor, zooming in to 100% magnification, and having a uniformly lighted viewing environment will aid you in correcting your RAW conversions.
The uniformity of the viewing environment (i.e., the ambient lighting where you view your computer monitor) is critical, for if your ambient lighting changes throughout the day and night, you can’t tell with any degree of precision what you’re working with. You’re playing a game with movable boundaries. So, if your monitor sits adjacent to an open window, things look quite different on a sunny day, a cloudy day, at night, or under any other set of changing conditions. If you’re serious about obtaining the best possible images, you must create an environment where the lighting remains constant whenever you’re working.