Apple Aperture 2 - Manual (Page 408)

408 Part III Performing Image Adjustments
Working with the White Balance Controls
You use the White Balance adjustment controls to change the color temperature and
color tint of an image. If an image has pixels that are supposed to be pure white, you
can use the White Balance eyedropper to automatically adjust the color temperature
and tint, or you can adjust the color temperature and tint manually. In most cases, the
automatic adjustment succeeds in removing the color cast from the image. If the White
Balance eyedropper does not completely remove the color cast from the image, you
can use the Temp and Tint adjustment controls to fine-tune the image.
Although Aperture can set the white balance of the image with great accuracy,
sometimes you have to use a combination of these two methods to have the image
appear with the warm or cool tonality you intended.
Before White Balance adjustment After White Balance adjustment