Name
	algorithm - The Scale2x, Scale3x and Scale4x algorithm

Scale2x Algorithm
	The effect works repeating a computation pattern for every
	pixel of the original image.
	The pattern starts from a square of 9 pixels and expands the
	central pixel computing 4 new pixels.

	Starting from this pattern :

		:A B C
		:D E F
		:G H I

	The central pixel E is expanded in 4 new pixels:

		:E0 E1
		:E2 E3

	with these rules (in C language) :

		:E0 = D == B && B != F && D != H ? D : E;
		:E1 = B == F && B != D && F != H ? F : E;
		:E2 = D == H && D != B && H != F ? D : E;
		:E3 = H == F && D != H && B != F ? F : E;

	which can be rewritten as :

		:E0 = D == B && B != H && D != F ? D : E;
		:E1 = B == F && B != H && D != F ? F : E;
		:E2 = D == H && B != H && D != F ? D : E;
		:E3 = H == F && B != H && D != F ? F : E;

	and optimized as:

		:if (B != H && D != F) {
		:	E0 = D == B ? D : E;
		:	E1 = B == F ? F : E;
		:	E2 = D == H ? D : E;
		:	E3 = H == F ? F : E;
		:} else {
		:	E0 = E;
		:	E1 = E;
		:	E2 = E;
		:	E3 = E;
		:}

	The image border is computed reusing the value of the nearest pixel
	on the border when the value of a pixel over the border is required.

Scale3x Algorithm
	Starting from this pattern :

		:A B C
		:D E F
		:G H I

	The central pixel E is expanded in 9 new pixels:

		:E0 E1 E2
		:E3 E4 E5
		:E6 E7 E8

	with these rules (in C language) :

		:E0 = D == B && B != F && D != H ? D : E;
		:E1 = (D == B && B != F && D != H && E != C) || (B == F && B != D && F != H && E != A) ? B : E;
		:E2 = B == F && B != D && F != H ? F : E;
		:E3 = (D == B && B != F && D != H && E != G) || (D == H && D != B && H != F && E != A) ? D : E;
		:E4 = E
		:E5 = (B == F && B != D && F != H && E != I) || (H == F && D != H && B != F && E != C) ? F : E;
		:E6 = D == H && D != B && H != F ? D : E;
		:E7 = (D == H && D != B && H != F && E != I) || (H == F && D != H && B != F && E != G) ? H : E;
		:E8 = H == F && D != H && B != F ? F : E;

	and optimized as:

		:if (B != H && D != F) {
		:	E0 = D == B ? D : E;
		:	E1 = (D == B && E != C) || (B == F && E != A) ? B : E;
		:	E2 = B == F ? F : E;
		:	E3 = (D == B && E != G) || (D == H && E != A) ? D : E;
		:	E4 = E;
		:	E5 = (B == F && E != I) || (H == F && E != C) ? F : E;
		:	E6 = D == H ? D : E;
		:	E7 = (D == H && E != I) || (H == F && E != G) ? H : E;
		:	E8 = H == F ? F : E;
		:} else {
		:	E0 = E;
		:	E1 = E;
		:	E2 = E;
		:	E3 = E;
		:	E4 = E;
		:	E5 = E;
		:	E6 = E;
		:	E7 = E;
		:	E8 = E;
		:}

Scale4x Algorithm
	The Scale4x effect is simply the Scale2x effect applied two times.