图像插值处理的方法

f0,f1,f2,f3为取样点所在行的指针，u,v为小数，dst指针指向目标像素

 

1.双线性插值-BiLinear Interpolation

 

typedef double FLPT;void BiLinear(UCHAR *f0, UCHAR *f1, FLPT u, FLPT v, UCHAR *dst){FLPT r0, r1, rt; for(int i = 0; i < 3; ++i){r0 = (1- u) * f0[i] + u * f0[i+3];r1 = (1- u) * f1[i] + u * f1[i+3]; rt = (1-v)*r0+v*r1 + 0.5;if(rt < 0){rt = 0;}else if(rt > 255){rt = 255;} dst[i] = (UCHAR)rt;}}

 

 2.双三次插值-BiCubic Interpolation

 

typedef double FLPT;FLPT Cubic(FLPT x){FLPT tmp = fabs(x); if(tmp < 1) { FLPT k2,k3; k2 = tmp*tmp; k3 = tmp*k2; return 1 - 2*k2 + k3; } else if(tmp < 2) { FLPT k1,k2,k3; k1 = tmp; k2 = k1*k1; k3 = k1*k2; return 4 - 8*k1 + 5*k2 - k3; } else { return 0; }}void BiCubic(UCHAR *f0, UCHAR *f1, UCHAR *f2, UCHAR *f3, FLPT u, FLPT v, UCHAR *dst){ FLPT Su0, Su1, Su2, Su3; FLPT Sv0, Sv1, Sv2, Sv3; Su0 = Cubic(1 + u);Su1 = Cubic(u);Su2 = Cubic(1 - u);Su3 = Cubic(2 - u);Sv0 = Cubic(1 + v);Sv1 = Cubic(v);Sv2 = Cubic(1 - v);Sv3 = Cubic(2 - v);FLPT r0, r1, r2, r3, rt; for(int k = 0; k < 3; ++k){r0 = f0[k]*Su0 + f0[k+3]*Su1 + f0[k+6]*Su2 + f0[k+9]*Su3;r1 = f1[k]*Su0 + f1[k+3]*Su1 + f1[k+6]*Su2 + f1[k+9]*Su3;r2 = f2[k]*Su0 + f2[k+3]*Su1 + f2[k+6]*Su2 + f2[k+9]*Su3;r3 = f3[k]*Su0 + f3[k+3]*Su1 + f3[k+6]*Su2 + f3[k+9]*Su3;rt = r0*Sv0 + r1*Sv1 + r2*Sv2 + r3*Sv3 + 0.5;if(rt > 255){rt = 255;}else if(rt < 0){rt = 0;}dst[k] = (UCHAR)rt;}}  

 

 

 

wiki上的相应链接：

1.http://zh.wikipedia.org/zh-hans/%E5%8F%8C%E7%BA%BF%E6%80%A7%E6%8F%92%E5%80%BC

2.http://en.wikipedia.org/wiki/Bicubic_interpolation