Scaling method by using cubic-like triple point slop control (CTPSC)

1. A method for scaling a source data to a destination data, implemented in a scaling device to provide the destination data in display or analysis, wherein three reference points of the source data denoted as −1, 0, and 1 by quantities of f(−1), f(0), and f(1) are used, in which f(x) is used to describe the destination data with a range between the points of 0 and 1, and f(x) is a quadratic form with three coefficients a, b, c for f(x)=ax 2 +bx+c, the method comprising:

setting an initial condition comprising setting a midpoint 0.5 with a quantity of f(0.5)=[f(0)+f(1)]/2 and f′(0)=f′(1)=DG, wherein D is a slope of [2f(0)−f(−1)−f(1)], and G is a gain factor to adjust the slope;

applying a constraint on the f(x) by passing through the points of 0, 0.5, and 1 by quantities of f(0), f(0.5), and f(1);

solving the coefficients of a, b, and c for f(x) by a range of 0≦x<0.5 and a range of 0.5≦x<1, so that the f(x) is symmetric or substantially symmetric to the midpoint,

wherein the solved function f(x) is used to generate the destination data to be displayed or analyzed in an application unit.

2. The method of claim 1 , wherein the f(x) is set to be

f ( x )=2[ f (1)− f (0)− DG]x 2 +( DG ) x+f (0) for 0≦x<0.5; and

f ( x )=2[ DG+f (0)− f (1)] x 2 +[4 f (1)−4 f (0)−3 DG]x+[DG−f (1)+2 f (0)] for 0.5≦x<1.

3. The method of claim 2 , wherein the coefficients of a, b, and c for the f(x) is based on the equations comprising:

for 0≦x<0.5,

f (0)= c,

f ′(0)= b=[ 2 f (0)− f (−1)− f (1)] G=DG,

f (0.5)=0.25 a+ 0.5 b+c= 0.5[ f (0)+ f (1)]= M ; and

for 0.5≦x<1

f (1)= a+b+c,

f ′(1)=2 a+b=[ 2 f (0)− f (−1)− f (1)] G=DG

f (0.5)=0.25 a+ 0.5 b+c= 0.5[ f (0)+ f (1)]= M.

4. The method as claimed in claim 1 , wherein the function is determined by setting

f ( x )=2[ f (1)− f (0)− DG]x 2 +( DG ) x+f (0) for 0≦x<0.5; and

F ( z )=2[ f (0)− f (1)+ DG]z 2 +( DG ) z+f (1) for −0.5≦z<0 wherein Z-transform of Z ( z )= X ( x )−1 is applied.

5. The method as claimed in claim 4 , further comprising solving the coefficients a, b, and c of the function f(x) based on the following equations:

for 0≦x<0.5:

f (0)= c

f ′(0)= b=[ 2 f (0)− f (−1)− f (1)] G=DG

f (0.5)=0.25 a+ 0.5 b+c= 0.5[ f (0)+ f (1)]; and

for −0.5≦ z< 0

F (0)= c=f (1)

F ′(0)= b=[ 2 f (0)− f (−1)− f (1)] G=DG

F (−0.5)=0.25 a− 0.5 b+c=M= 0.5[ f (0)+ f (1)].

6. A scaling circuit, used to scale input data and export output data, wherein the circuit employs a curve function f(x) to describe the output data, wherein the f(x) is determined by choosing three reference points of the source data denoted as −1, 0, and 1 by quantities of f(−1), f(0), and f(1) for use, wherein the f(x) is used to describe the output data with a range between the points of 0 and 1, and f(x) is a quadratic form of with three coefficients a, b, c for f(x)=ax 2 +bx+c, the circuit comprising:

a initial circuit unit to set an initial condition comprising setting a midpoint 0.5 with a quantity of f(0.5)=[f(0)+f(1)]/2 and f′(0)=f′(1)=DG wherein D is a slope of [2f(0)−f(−1)− f (1)], and G is a gain factor to adjust the slope; and

a solving circuit part to solve the f(x) under a constraint on the f(x) by passing through the points of 0, 0.5, and 1 by quantities of f(0), f(0.5), and f(1), and solve the coefficients of a, b, and c for f(x) by a range of 0≦x<0.5 and a range of 0.5≦x<1, so that the f(x) is symmetric or substantially symmetric to the midpoint.

7. The scaling circuit of claim 6 , wherein the f(x) is set to be

f ( x )=2[ f (1)− f (0)− DG]x 2 +( DG ) x+f (0) for 0≦x<0.5; and

f ( x )=2[ DG+f (0)− f (1)] x 2 +[4 f (1)−4 f (0)−3 DG]x+[DG−f (1)+2 f (0)] for 0.5≦x<1.

8. The scaling circuit of claim 7 , wherein the coefficients of a, b, and c for the f(x) is based on the equations comprising:

for 0≦x<0.5,

f (0)= c,

f ′(0)= b=[ 2 f (0)− f (−1)− f (1)] G=DG,

f (0.5)=0.25 a+ 0.5 b+c= 0.5[ f (0)+ f (1)]= M ; and

for 0.5≦x<1

f (1)= a+b+c,

f ′(1)=2 a+b=[ 2 f (0)− f (−1)− f (1)] G=DG

f (0.5)=0.25 a+ 0.5 b+c= 0.5[ f (0)+ f (1)]= M.

9. The scaling circuit of claim 6 , wherein the function is determined by setting

f ( x )=2[ f (1)− f (0)− DG]x 2 +( DG ) x+f (0) for 0≦x<0.5; and

F ( z )=2[ f (0)− f (1)+ DG]z 2 +( DG ) z+f (1) for −0.5≦z<0 wherein Z-transform of Z ( z )= X ( x )−1 is applied.

10. The scaling circuit of claim 9 , further comprising solving the coefficients a, b, and c of the function f(x) based on the following equations:

for 0≦x<0.5:

f (0)= c

f ′(0)= b=[ 2 f (0)− f (−1)− f (1)] G=DG

f (0.5)=0.25 a+ 0.5 b+c= 0.5[ f (0)+ f (1)]; and

for −0.5≦z<0

F (0)= c=f (1)

F ′(0)= b=[ 2 f (0)− f (−1)− f (1)] G=DG

F (−0.5)=0.25 a− 0.5 b+c=M= 0.5[ f (0)+ f (1)].

11. A method for generating destination data samples f(x) in response to three source data samples f(−1), f(0) and f(1), the method being implemented in a scaling device to provide the destination data samples for display or analysis, wherein f(x) is generated for x in a range of 0≦x<1, said method comprising the steps of:

(a) generating a middle point sample f(0.5) by defining f(0.5)=[f(0)+f(1)]/2;

(b) fitting a quadratic equation of f(x)=ax 2 +bx+c to said source data samples f(0) and f(1) and said middle point sample f(0.5); and

(c) generating a resulting equation f(x)=2[f(1)−f(0)−DG]x 2 +(DG)x+f(0) for one subregion of 0≦x<0.5 and f(x)=2[DG+f(0)−f(1)]x 2 +[4f(1)−4f(0)−3DG]x+[DG−f(1)+2f(0)] for another subregion of 0.5≦x<1, wherein DG designates a slope at said source data samples f(0) and f(1) and is determined by said source data samples f(−1), f(0) and f(1), wherein the resulting equation f(x) is utilized to generate the destination data samples for display or analysis in an application unit.

12. The method as claimed in claim 11 , further comprising;

(d) converting f(x)=2[DG+f(0)−f(1)]x 2 +[4f(1)−4f(0)−3DG]x+[DG−f(1)+2f(0)] for said another subregion of 0.5≦x<1 into F(z)=2[f(0)−f(1)+DG]z 2 +(DG)z+f(1) for −0.5≦z<0, wherein Z-transform of Z(z)=X(x)−1 is applied.

13. The method as claimed in claim 11 , wherein D is defined to be [2f(0)−f(−1)−f(1)] and G is a gain factor.