You are to implement a subband image coder in a software environment of your choice. Your encoder will perform the subband decomposition, scalar quantization and entropy encoding to a typical input image, and produce a coded bit stream stored as a data file. Your decoder will read in this coded file and perform entropy decoding and subband reconstruction, and finally produce a reconstructed image in the same format of the input image. You will then calculate the Peak$-$Signal$-$to$-$Noise ratio of your reconstructed image to evaluate the performance of your image coder. Your image coder should be able to accept an input parameter which specifies the quantization step size, and this parameter will ultimately be used to control the size of the coded data file $($or the compression ratio$).$