appcoef2 - Two Dimension Approximation Coefficent Reconstruction
appcoef2 is for extraction or reconstruction of approximation coeffient at different level after a multiple level decompostion. Extension mode is stored as a global variable and could be changed with dwtmode. If N is omitted, maximum level approximation will be obtained.
x=rand(100,100); [C,S]=wavedec(x,3,'db2'); A2=appcoef(C,S,'db2',2);
Roger Liu and Isaac Zhi