The Eyedroppers are very popular tools. They can be found in both the Levels dialogue box (see Figure 1) and the Curves dialogue box (see Figure 2). As can be seen in these Figures, there are three Eyedroppers. The left Eyedropper is the Black Eyedropper and is used to set the black point or shadow values. The right Eyedropper is the White Eyedropper and is used to set the white point or highlight values. The middle Eyedropper is the Gray Eyedropper and is used to set the midtones in the image.
While the Eyedroppers are very useful, there is a problem. The proper use of these tools requires a bit of sophistication on the part of the photographer that is using them. The issue is that the Eyedroppers are not always the best tool for the job. This is because the Eyedroppers can easily cause color shifts in an image to which they are applied. In some cases, this is desired. In fact, because the Eyedroppers can create color shifts, they are frequently used to correct colorcasts. On the other hand, improper use of the Eyedroppers can induce unwanted color shifts in images.
The reason that I wrote this article is that I see some photographers improperly using the Eyedroppers. Thus, the purpose of this article is to look at the Eyedroppers and how they affect an image with the intention of setting some guidelines for how the Eyedroppers should be used and when another approach should be chosen. It is assumed that the reader has a working knowledge of the Eyedroppers. For those that want a review of these tools, the tools are covered in my series on Levels (for more information on the use of the Eyedroppers with Levels see, Levels -- Part II) and Curves (for more information on the use of the Eyedroppers with Curves, see Curves -- Part III).
Figure 3 shows an image that has no colorcast. However, the image is a bit flat. This can also be seen in the Histogram in Figure 4. The figure shows tonal gaps at both ends of the Histogram. This indicates that there are few true whites or blacks in the image (for more information on reading Histograms, see Histograms -- Part I). This can be corrected by setting the shadow and highlight values with the eyedroppers. However, since this image has no colorcast, it is critical that no colorcast be created when the eyedroppers are used.
To set the highlight values, the White Eyedropper is simply moved around the light areas of the image (the curser turns into the White Eyedropper as it is moved over the image). As the White Eyedropper is moved around, the Info palette indicates the tonal values of the location directly below the White Eyedropper. For the setting of the highlight values, it is desired to find a position that has very high tonal values but still holds detail. Since this image has no colorcast, it is necessary for the position to be fairly neutral.
Figure 9 shows the location selected for setting the highlights (a color sampler had previously been placed at this location). Figure 10 shows the Info palette reading for this location.
To set the shadow values, the Black Eyedropper is simply moved around the dark areas of the image (the curser turns into the Black Eyedropper as it is moved over the image). As the Black Eyedropper is moved around, the Info palette indicates the tonal values of the location directly below the Black Eyedropper. For the setting of the shadow values, it is desired to find a position that has very low tonal values but still holds detail. Since this image has no colorcast, it is necessary for the position to be fairly neutral.
Figure 13 shows the location selected for setting the shadows (a color sampler had previously been placed at this location). Figure 14 shows the Info palette reading for this location.
Again, the Info palette shows that the selected location is almost perfectly neutral, and moving the Black Eyedropper around shows that there is detail in this area. The Black Eyedropper is clicked at this location.
Moving the Black Eyedropper around shows that this image has darker areas than this location (some of the values in these darker areas are around 24). However, these darker areas are not neutral. Because of this, the values in the Color Picker where set at 8, 8, 8, rather than a lower number, so that the darker shadows would not be clipped.
This brings us to the first conclusion. A photographer should use the White and Black Eyedroppers, with neutral images, only if he is very careful to select neutral locations for setting the highlights and shadows. If the photographer does not want to be meticulous in selecting these locations, he should choose another method of setting the highlights and shadows (other methods are covered in the series on Levels and Curves).
The Eyedroppers can be used to set the highlights and shadows and to correct a colorcast at the same time. However, there is a limitation to this approach. It can be used only with images that have highlights and shadows that should be neutral after the application of the Eyedroppers.
Figure 22 shows an image that has a blue colorcast. This image is a good candidate for using the Eyedroppers to correct the colorcast. This is because the highlights in the flowing water should be a clean white. Similarly, the shadows should have no tint.
Figure 25 shows the values of the location where the shadows will be set. It can be seen that this location also has a large amount of blue.
The highlight and shadow values are now set using the same procedure used in the example above. Figure 26 and 27 show the image before and after the highlights and shadows were set.
Thus, we come to the second conclusion. A photographer should use the White and Black Eyedroppers to set the highlight and shadow values, with images that have a colorcast, only when the image has highlights and shadows that should be neutral in the final image.
The Eyedroppers are a great tool, but only for photographers that are willing to study their images to determine the color nature of the highlights and shadows and to customize the use of the Eyedroppers to the specific needs of each image. In other words, a photographer can not blindly apply the eyedroppers to all images in the same way and expect to get good results. The use of the Eyedroppers must be customized for each image.