For further with gradients, a third point can enrich them. We go from a straight line segment to a quadratic Bezier curve by adding a point of control that will play a role attractor for the points of the initial right segment. This kind of curve is prevalent in software vector drawing especially since it makes it easy to draw parabolic curves.

Figure 6a shows the straight line segment used in the gradient of the figure 2.

The curve of Figure 6b has the same start and end points that the straight line segment on 6a. It’s the moving of the control point which distorts the straight line segment into parabolic curve.

The flatness of the linear gradients is appreciable in certain circumstances or in certain domains such as the visualization of statistical data because it allows a neutral presentation. In contrast, allowable variations by a quadratic curve between two points are interesting because of their dynamics. Opposite visualization of the straight line segment used for the linear gradient of the previous page and a quadratic gradient between the two same points. Figure 7, the rendering of the quadratic gradient.

Three points define a plan. Among the figures that fit in a plan are the polygons. It is practical to use them because they allow to determine in advance the number of colors. In this case it will be the number of vertices of the polygon.

Figure 8 shows the vertices and the graphic rendering of a heptagon.

We can notice a similarity between this rendering and that of the figure 4. Indeed the circle in which fits the heptagon into the CIELAB system corresponds to linear gradient in a landmark Cartesian coordinates LCH.