The Tone Mapping control uses a curve based input control. The control consists of two parts: "Graph" part and "Text" part. The "Text" part presents the "reference" points, which are illustrated inthe "Graph" part by rectangles. The curve is constructed on the basis of the "reference" points using the Lagrange polynomials (with condition that x, y should be inside [0,1]). The curve must contain at least two points to be valid (0 0) and (1 1). The curve can be edited as through the "Graph" part and through the "Text" part inthe following way:

• Adding the reference point. Can be done through the "Text" part by the adding the new pair (xi, yi) or by using the mouse, clicking on the "Graph" to set the point. It should be far enough from already created reference points (if it is too close to an existing point that point will be selected and ready for the dragging). If created by mouse the new point will be automatically selected and ready for the dragging.
• Changing the reference point. Can be done through the "Text" part by changing some pair (xi, yi) or by mouse by clicking and dragging.
• Removing the reference point. Can be done through the "Text" part by the removing the appropriate pair (xi, yi) or through the "Graph" part by using keyboard (pressing "Delete" button) when the mouse cursor is inside the rectangle of the appropriate point. The point must not be selected.