Define a color gradient by specifying its two extrema colors.
Begin Color (RGBA Color) : First color of the gradient
End Color (RGBA Color) : Last color of the gradient
Mid Point (Percentage) : Middle point of the gradient (50% by default)
Standard Presets: White To Black, Red to Black, Green to Black, Blue to Black, White to Alpha, Black to Alpha, Red to Alpha, Green to Alpha and Blue to Alpha
Advanced Presets: Binarize Black and White