Whites and Blacks Adjustments

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Today’s Question: This question concerns the Whites and Blacks sliders that are found in Adobe Camera Raw as well as Lightroom. It is not clear from the literature exactly what they are meant to do. Would you please be so kind to elaborate on their purpose and how they are to be applied?

Tim’s Quick Answer: While the tonal value of virtually all pixels in the image may be adjusted by changing the value for the Whites and Blacks sliders, the primary goal is to establish the value for the brightest and darkest pixels in the image, respectively.

More Detail: To better understand the effect of the Whites and Blacks adjustments in Adobe Camera Raw and Lightroom, I think it is important to reflect on the histogram for the image. In addition, I think it is helpful to think of that histogram as being an elastic object that can be stretched out or compressed as needed.

The distribution of tonal values represented on the histogram effectively indicates the overall tonal range captured in your photo. A low-contrast scene may have a relatively narrow histogram, while a high-contrast scene will have a wider histogram. The far left of the histogram represents the darkest pixel values in the image, and the far right represents the brightest pixels in the image.

As a very general rule, with a typical photograph we want the brightest pixels to be white (or nearly white) and the darkest pixels to be black (or nearly black). There are obviously countless exceptions to this general rule, but the Whites and Blacks sliders are perhaps most important (or at least easiest to understand) if we assume this goal to be valid.

By increasing the value for the Whites slider you are brightening the image, essentially pulling the right end of the histogram further to the right. Naturally, other tonal values within the image beyond the very brightest pixels will also be affected. The Blacks slider performs a similar function, with the emphasis on the left end of the histogram that represents the darkest pixels in the image.

You can adjust the values for the Whites and Blacks sliders to effectively define the tonal value for the brightest and darkest pixels in the image. In many cases that might mean going right up to the point of just about clipping highlight or shadow detail. In other cases it might mean “pulling back” these values to help preserve detail that might have otherwise been lost. In all cases it is important to keep in mind that after adjusting the values for Whites and Blacks, any modification of the other tonal adjustments (Exposure, Contrast, Highlights, and Shadows, for example) may effectively override the adjustment you applied with the Whites and Blacks sliders. As such, it is important to revisit the Whites and Blacks sliders to check for clipping toward the end of your final adjustment review.

Note, by the way, that you can see a clipping preview display while adjusting the Whites and Blacks sliders by holding the Alt key on Windows or the Option key on Macintosh while dragging the slider itself.