N, P, S, H
If one of these four buttons is activated you will see the mask that is used for the correction in the preview. The N button shows a negative view of the mask, the P buttons shows the positive version of the mask. The S buttons shows only the shadow areas, spot areas or selected color areas depending on which mode you are currently using. The H button shows the highlight or background areas.
If you have Split View and the Multiple check box active, you can use these four buttons to display the processed image side by side with the mask.
Adding Colors to the Mask
The easiest way to add a color to the color mask is by using the cross key. After you activated the cross tool above the preview, click on the preview to select a color that you want to add to the color mask. Now the Color combo box automatically switches to this color and sets the Intensity slider to a value of 255. To remove a color from the color mask again shift click with the cross tool on that color in the preview.
It works best if you select a color that is limited to a certain image area. Colors that are distributed over various image objects and areas and without strict color borders are less suitable. Also, if an image has a color cast that spreads all over the image can decrease the effectively of the Colors modes. In such a case it is best to correct the color cast at first. However, if you only want to adjust the brightness and contrast of a color area, it don't matter much that much and even overlapping color areas work fine. Using the Radius slider can help, too.
Color
The Color combo box lets you select the six main colors Red, Green, Blue, Cyan, Magenta and Yellow. The four sliders beneath can have different values for each of the six color options. The slider values of each color option are used to create a color mask.
Invert
The Invert check box lets you invert the color mask.
Intensity
Defines how much the color that is selected in the Color combo box contributes to the color mask. If it is set to zero, the image areas with that color are ignored. If it is set to 255, image areas with that color are added to the mask.
Impact
The Impact slider lets you intensify the selected color. It increases the contrast of that color in the color mask and increases the intensity of the applied effect. Values up to 50 are recommended, but higher values may produce hard edges in the image.
Radius
The Radius slider lets you smooth the individual mask of a selected color. This can be helpful to create a smooth transition and avoid hard edges, but a too high value may also produce unwanted glow effects, so-called halos.
Range
The Range slider lets you shrink or expand the range of the currently selected color and exclude currently selected areas or include other areas, too.