saturate method
Implementation
ContainerBuilder saturate(double value) => colorFilter(ColorFilter.matrix([
0.213 + 0.787 * value, 0.715 - 0.715 * value, 0.072 - 0.072 * value, 0, 0,
0.213 - 0.213 * value, 0.715 + 0.285 * value, 0.072 - 0.072 * value, 0, 0,
0.213 - 0.213 * value, 0.715 - 0.715 * value, 0.072 + 0.928 * value, 0, 0,
0, 0, 0, 1, 0,
]));