Java Doc for InterpolationBicubic2.java in  » 6.0-JDK-Modules » Java-Advanced-Imaging » javax » media » jai » Java Source Code / Java DocumentationJava Source Code and Java Documentation

InterpolationBicubic2 is a subclass of Interpolation that performs interpolation using the piecewise cubic polynomial:

 r(x) = (a + 2)|x|^3 - (a + 3)|x|^2         +  1 , 0 <= |x| < 1
 r(x) =       a|x|^3 -      5a|x|^2 + 8a|x| - 4a , 1 <= |x| < 2
 r(x) = 0                                        , otherwise
 

A neighborhood extending one sample to the left of and above the central sample, and two samples to the right of and below the central sample is required to perform bicubic interpolation.

This implementation creates an InterpolationTable whose integer coefficients have eight bits of precision to the right of the binary point.

The diagrams below illustrate the pixels involved in one-dimensional interpolation. Point s0 is the interpolation kernel key position. xfrac and yfrac, indicated by the dots, represent the point of interpolation between two pixels. This value lies between 0.0 and 1.0 exclusive for floating point and 0 and 2^{subsampleBits} exclusive for integer interpolations.

 
 Horizontal              Vertical
 s_    s0 .  s1    s2            s_                             
 ^                                                     
 xfrac                   s0                        
 .< yfrac                  
 s1                         
 s2                         
 
 

The diagram below illustrates the pixels involved in two-dimensional interpolation.

 
 s__    s_0    s_1    s_2                              
 s0_    s00    s01    s02                              
 .             < yfrac                      
 s1_    s10    s11    s12                              
 s2_    s20    s21    s22                              
 ^                                           
 xfrac                                        
 
 

The class is marked 'final' so that it may be more easily inlined.

This implementation creates an InterpolationTable whose integer coefficients have eight bits of precision to the right of the binary point.
Parameters:
  subsampleBits - the subsample precision.