Image Processing Reference
The image after setting the exposure and applying the white balance with the eyedropper
Spot White Balance
This function offers a simple option to correct colors if the image shows a
color cast. Select the eyedropper and then click on an area in your image that
ought to be white, neutral gray, or black. By holding down your left mouse
button and dragging, you can enlarge your selection. Then click again on the
eyedropper symbol. The colors in the image will be recalculated so that the
selected point or area is white, gray, or black.
Through the selection of a white spot (or neutral gray spot), you tell the
program what is to be considered white. This way you can remove a color tint
in your image, assuming, of course, that you are able to determine white, gray,
or black sections in the picture.