Note
If you’re serious about obtaining the best possible images, you must create an environment where the lighting remains constant whenever you’re working on your computer.
In ACR, the Lens Corrections tab includes sliders to correct for color fringing and for lens vignetting. The Sharpening tab contains the settings for noise reduction. The Camera Calibration tab is the place to import and apply any custom camera profile you may have and to fine-tune the color rendering in each of the color channels. Move the sliders and study the results. When you have arrived at a group of settings that gives consistently good results with your camera-lens combination, you can save the settings for each tab in ACR and apply the settings automatically to any number of captures taken with the same camera and lens.
Typical of ACR, the settings are not applied until the image is processed, so you can go back and forth between settings and tabs if necessary, and your custom settings can be saved and recalled for reuse.
Sharpening the Capture
One area of image correction that deserves particular attention is that of sharpening. Each step in the process from capture to print causes a degradation in the sharpness of the image. The fix is what is referred to as sharpening and works by increasing the local contrast along the boundaries between lighter and darker portions of the image. In theory, the software finds edges (the boundaries between lighter and darker areas) and then darkens the darker side and lightens the lighter side of the edge. In practice, what Photoshop registers as an edge may simply be an area of local contrast where you do not want to exaggerate tonal differences. To be effective, sharpening must be strong enough to carry the illusion of sharpness but not so strong as to create undesirable halos or visible outlines, introduce granularity in areas of more or less smooth tonalities, or worse yet, pucker skin tones. Not surprisingly, the difference between effective sharpening and oversharpening is often small, leading to the truism: sharpen but don’t oversharpen.
Common practice is to perform sharpening in two stages. First, do a modest sharpening in the RAW converter to produce a realistic presentation with which to do your editing, and then do a second, output sharpening just before printing. Every photographer has his or her approach to sharpening and you will acquire your own.
To get started with sharpening in ACR, you will find the sharpening controls under the Detail tab. Zoom in to view the image at 100 %. To see the affect of your changes, first exaggerate the Amount setting, then refine the Radius and Detail sliders. As a rule, images with predominately fine detail (e.g., pine needles on the ground, old wood on an abandoned building, stonework inside a cathedral, etc.) often look best with a small radius setting such as 0.7–0.8, and images with areas of smooth texture (e.g., skin tones, lightly rippled water, smooth surfaces like concrete) often look best with a radius setting of 1.2–1.4.
Next adjust the Masking slider to confine the sharpening to the true edges. Increasing the masking slider restricts the sharpening to tonal differences that are more likely to be edges. If you want to view the mask as you make changes to the Masking setting, hold down the Option/Alt key and move the Masking slider. The black areas are masked and will not be sharpened; the white areas are treated as edges and will be sharpened. Finally, dial down the Amount until the overall effect is barely visible when viewed at 100 %. Use the preview checkbox to toggle between the sharpened and unsharpened versions. Refine as needed but resist any temptation to oversharpen. Depending on your camera, your computer display, and a number of other variables, you may find you need to increase or decrease the Amount. As you gain experience with different subject matter, you will acquire the judgment to sharpen any number of RAW captures of similar subject matter. You can save and recall the sharpening settings you routinely use.
The second stage of sharpening, output sharpening, should not be done until the image has been fully edited, saved as a separate file, resampled to final print size, and any layers you may have created in Photoshop have been flattened. The settings for the output sharpening depend on a number of factors including print size, image content (whether the image is made up of fine detail or broad areas of smooth tonalities), viewing distance, and the output medium (whether printed on glossy or matte paper).
Converting the Image to Black-and-White
In traditional (or classical) photography, you can use various contrast filters to cause black-and-white film to alter tonalities in the negative. Digitally, there are a number of approaches for converting the full color capture to grayscale. For example, in ACR, go to the HSL/Grayscale tab and check the Convert to Grayscale checkbox. On the image window, use the Target Adjustment Tool (use the v key as a shortcut) and drag the cursor over portions of the image. ACR will increase or decrease the percentage contribution of the color you dragged over. Alternatively, you can move the color sliders and observe the changes in the resulting grayscale image. Keep in mind that the resulting image will be saved as a grayscale image that you can convert to a three channel RGB image in Photoshop if you wish. In Lightroom you can use the On-Image adjustment tool to adjust the conversion of specific areas of the image. Using Lightroom, in the HSL-Color-Grayscale box in the Develop module, click on the double arrow symbol to the left of the palette, place the cursor over any part of the image, press the mouse key, and move the cursor up or down. Moving up will lighten the value of the color beneath the cursor; moving down will darken the value. Make changes over other parts of the image and watch the grayscale image change.
As an alternative to converting in ACR or Lightroom, you can save the file as an RGB color file and do the conversion with a Black and White adjustment layer in Photoshop. In Photoshop, in the Layers Menu select New Adjustment Layer and choose Black and White. An Adjustment palette will open. Click on the On-Image adjustment tool (indicated by a pointing hand and a double arrow) in the upper left of the palette, go to the image, click on an area, and move the cursor left and right. Moving to the right will lighten the grayscale rendering of the color information under the cursor, moving to the left will darken it. Move to different areas and repeat until you get the rendering you want. Alternatively, or in addition to using the On-Image tool, you can work the color sliders in the Adjustment palette and observe the results. One of the features of the Black and White layer is that the layer is nondestructive; you can always revise the Black and White layer settings after you have made other adjustments. You can also make more than one Black and White adjustment layer, compare the results, and use layer masks to reveal different portions of different Black and White conversion layers. I discuss more about masking below.
Output Formats and Bit Depth
Output from the RAW converter should be saved using a file format that preserves all of your hard-earned data. The two most commonly used formats are TIFF and PSD. Although there are technical differences between the two, both will preserve all of your photographic information as long as you set the output to be saved in 16 bits/channel with the color space set to ProPhoto RGB. In ACR, the output settings are located at the bottom center of the image window.