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124 lines
3.3 KiB
124 lines
3.3 KiB
#include <includes.hpp>
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#include <utilities.hpp>
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#include <boost/filesystem.hpp>
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#include <png.hpp>
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#include "jcmp.hpp"
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#include "wavelet.hpp"
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using namespace wvlt;
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using namespace jcmp;
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// note: we take a copy, because we will modify it in place
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static image compress(std::vector<double> img, uint width, double threshold, unsigned int& nzeros){
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uint height = img.size() / width;
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assert(is_pow_of_two(width));
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assert(is_pow_of_two(height));
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// wavelet transform in x-direction
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for(unsigned int i = 0; i < height; ++i){
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wavelet(&img[i*width], width, 1);
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}
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// wavelet transform in y-direction
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for(unsigned int i = 0; i < width; ++i){
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wavelet(&img[i], height, width);
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}
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double min_abs = 10000.0;
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double max_abs = 0.0;
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for(auto& el : img){
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auto absel = std::abs(el);
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if(absel > threshold) {
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min_abs = std::min(min_abs, absel);
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max_abs = std::max(max_abs, absel);
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} else {
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el = 0;
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}
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}
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auto q = quantization::get(quantization::type::logarithmic, max_abs, min_abs);
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// save the principal coefficients
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std::vector<jcmp::coefficient> v;
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for(unsigned int y = 0; y < height; ++y){
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for(unsigned int x = 0; x < width; ++x){
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auto&& el = img[x + width*y];
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if(el != 0) v.push_back({q.forwards(el), uint(x), uint(y)});
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}
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}
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nzeros = v.size();
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return image(width, height, q.p, std::move(v));
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}
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static std::vector<double> decompress(image in){
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auto width = in.header.width;
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auto height = in.header.height;
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assert(is_pow_of_two(width));
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assert(is_pow_of_two(height));
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auto q = in.header.get_quantization(quantization::type::logarithmic);
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std::vector<double> image(width * height, 0.0);
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// read in coefficient on coordinates
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for(auto it = in.data.begin(); it != in.data.end(); ++it){
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auto&& x = *it;
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image[x.x + width*x.y] = q.backwards(x.c);
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}
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in.clear();
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// inverse wavelet transform in y-direction
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for(unsigned int i = 0; i < width; ++i){
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unwavelet(&image[i], height, width);
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}
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// inverse wavelet transform in x-direction
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for(unsigned int i = 0; i < height; ++i){
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unwavelet(&image[i*width], width, 1);
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}
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return image;
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}
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int main(){
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namespace fs = boost::filesystem;
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fs::path directory("images");
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fs::directory_iterator eod;
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for(fs::directory_iterator it(directory); it != eod; ++it){
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auto && path = it->path();
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if(path.extension() != ".png") continue;
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// open file
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std::string filename = path.string();
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std::cout << field("file") << filename << std::endl;
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png::istream image(filename);
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auto width = image.get_width();
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auto height = image.get_height();
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// read into vector
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std::vector<double> image_vec;
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image_vec.reserve(width * height);
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for(unsigned char c = 0; image >> c;) image_vec.push_back(c/255.0);
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// compress and decompress to see how we lost information
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unsigned int nzeros = 0;
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auto compressed_vec = decompress(compress(image_vec, width, 5.0, nzeros));
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// output some information
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std::cout << field("raw") << width*height << std::endl;
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std::cout << field("compressed") << nzeros/double(width*height) << std::endl;
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std::cout << field("nz") << nzeros << std::endl;
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// save to output file
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std::string cfilename = "compressed/" + std::to_string(nzeros) + path.filename().string();
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png::gray_ostream compressed_image(width, height, cfilename);
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for(unsigned int i = 0; i < compressed_vec.size(); ++i) compressed_image << compressed_vec[i];
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}
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}
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