5.     Eyedropper Tool

Another tool within the "Levels" and "Curves" dialog is the "eyedropper" tool. It's works identically in both "Levels" and "Curves". The "eyedropper" tool is actually a bit more complex to use than those discussed previously, but is extremely useful and so worth getting to know.

Using the "eyedroppers" for neutral pointing

The "eyedropper" tool is very useful for quickly neutralising some colour casts. We simply choose the centre "eyedropper" tool and then click a point in the image that we know should be neutral. This technique is sometimes called "neutral pointing". The screenshot below should provide some insight as the how useful "neutral pointing" can be. However, be aware that the area you select (mouse click) should already be fairly close to neutral otherwise major colour shifts will occur in other areas of the image.

 

Before	After

 

It is also possible to use the "Eyedropper" tool to neutralise colour casts in "highlight" and "shadow" regions, but this requires great care and is better left to those who fully understand the complexities of the "Eyedropper" tool (see Real World Photoshop 6/7 by Bruce Fraser and David Blatner for more details of this procedure).

"Targeting" or Assigning shadow and highlight points using the "Eyedroppers"

Earlier I described a very simple way to set the black and white points, i.e. the "value" for the darkest and brightest pixel in the image. When using the "Eyedropper" tool it is recommended that this step is taken after sharpening the image rather than as part of the normal editing procedure since applying sharpening tends to undo some of our "targeting" efforts. It's also important that we ensure that the pixels that we will be targeting really are neutral.

To configure the "eyedropper" tool for our preferred target values we begin by double clicking the shadow "eyedropper" icon and then adjusting the RGB values in the "Color Picker" dialog.

 

 

Default shadow eyedropper settings

 

If using one of the Epson Photo series printers then the "Shadow" can be set for a value of R=G=B=5 (2%) as shown below.

 

Shadow eyedropper set at 2%

 

Once set; we simply click the OK button and return to the "Levels" dialog. To set the "Highlight" value we repeat the above process, but this time we choose the highlight eyedropper, typical values seem to R=G=B between 245 and 250.

Now with our white or black eyedropper tool selected we find a point in our image that we want to make the brightest/darkest and simply click that point. Again the "Clipping Display" can be used to identify the location of the darkest/lightest pixels and then we zoom in close to areas that you think might be appropriate. If after clicking a point we realise that it was a poor choice then we simply use the "Ctrl+Z"  (or "Command+Z" on the Mac) keys to cancel the command and try again.

Layers Palette

Remember that I have been applying the various edits using "Adjustment Layers" so checking the "Layers" palette we should find a new "Levels" layer. In the example shown below we see the thumbnail of a histogram. This layer contains all the information relating to the adjustments we made in the "Levels" dialog.

 

Layers Palette

 

Double clicking the "Levels" layer will reopen the levels dialog and allow further adjustments. We can also get a "before and after" preview by simply clicking the "eye" icon.

Some recommend that we flatten the layers once the various adjustments have been completed. However, since an "Adjustment Layer" accounts for only a small increase in file size I believe saving it with the image is a more prudent approach, after all we never know what the future holds for the image. One thing that should be understood is that we cannot sharpen an adjustment layer. Therefore to sharpen our image prior to printing we simply make a duplicate (Image > Duplicate) and flatten the layers of the duplicate image.

Bringing it altogether

In preparing the final image I chose to use only a "Levels" adjustment layer. My first step was to neutralise the overall colour cast using the grey "eyedropper" tool. I followed this by setting the "black" and "white" points for the image using the "Shadow/highlight Clipping Displays" as an aid. I then used the red channel "midtone" slider to remove the remaining colour cast and finally applied some sharpening via the "Unsharp Mask" tool

 

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