Operation Manual

A value below 0.0 decreases the color saturation in the image, and a value above 0.0
increases the saturation of the nonsaturated colors. A value of –1.0 removes all color from
the image, making it grayscale except for any skin tones.
Setting the Tint of Black, Gray, and White Values in the Image
You use the Black Tint, Gray Tint, and White Tint color wheels when you want to selectively
remove color casts from the shadows, midtones, and highlights in the image. Color casts
are often caused by shooting in mixed lighting and unnatural lighting situations, where
the difference in the color from the mixture of multiple types of source lights can produce
a color variance in a specific tonal range in an image. For example, when shooting indoors,
interior incandescent (tungsten) lighting can often produce a yellow color cast through
the white colors in the image. Using the White Tint eyedropper, you can have Aperture
isolate the highlights and add blue to the white values, thereby reducing the yellow color
cast and returning the whites to neutral white.
There are two methods for selectively adjusting the tint values in an image: you can use
the Black Tint, Gray Tint, and White Tint eyedroppers to have Aperture automatically
adjust the tint to neutral color values, or you can use the Black Tint, Gray Tint, and White
Tint color wheels to manually adjust the tint values. The method you choose is determined
by the level of precision you require. The eyedroppers provide an accurate means of
identifying the color cast within the tonal range of each eyedropper and returning the
color values to neutral. However, depending on the subject, you may not want to
completely remove the color cast found in a specific tonal range. Therefore, you can
manually adjust the tint values in the shadows, midtones, and highlights using the Black
Tint, Gray Tint, and White Tint color wheels.
For more information about using the eyedroppers to adjust the black, gray, and white
tints in the image, see Using the Eyedroppers to Set the Tint in an Image.
For more information about manually adjusting the black, gray, and white tints in the
image, see Manually Setting the Tint in an Image.
Using the Eyedroppers to Set the Tint in an Image
You use the Black Tint, Gray Tint, and White Tint eyedropper tools when you want to
have Aperture selectively modify the tints of the shadows, midtones, and highlights in
an image automatically. Whereas using the White Balance controls adjusts the tints of all
tonal values in the image uniformly, the Black Tint, Gray Tint, and White Tint eyedropper
tools allow you to selectively neutralize color casts that affect only the shadows, midtones,
or highlights. In some difficult cases, you can use the Black Tint, Gray Tint, and White Tint
eyedropper tools in combination with the White Balance controls to first neutralize a tint
in a specific tonal range and then uniformly remove the tint from the rest of the image.
For more information about adjusting white balance, see Working with the White Balance
Controls.
518 Chapter 17 Making Image Adjustments