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107 lines
3.0 KiB
107 lines
3.0 KiB
#include <includes.hpp>
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#include <boost/filesystem.hpp>
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#include <png.hpp>
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#include <utilities.hpp>
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#include "compressed_image.hpp"
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#include "striding_iterator.hpp"
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#include "periodic_iterator.hpp"
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#include "wavelet.hpp"
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using namespace wvlt::V1;
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// note: we take a copy, because we will modify it in place
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jcmp::image compress(std::vector<double> image, int width, double threshold, int& zeros){
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auto height = image.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(int i = 0; i < height; ++i){
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wavelet(image.begin() + i*width, image.begin() + (i+1)*width);
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}
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// wavelet transform in y-direction
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for(int i = 0; i < width; ++i){
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wavelet(strided(image.begin() + i, width), strided(image.end() + i, width));
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}
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// save the principal coefficients
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std::vector<jcmp::coefficient> v;
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for(int y = 0; y < height; ++y){
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for(int x = 0; x < width; ++x){
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auto&& el = image[x + width*y];
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if(std::abs(el) > threshold) v.push_back({el, jcmp::uint(x), jcmp::uint(y)});
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else ++zeros;
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}
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}
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return jcmp::image(width, height, std::move(v));
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}
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std::vector<double> decompress(jcmp::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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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] = 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(int i = 0; i < width; ++i){
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unwavelet(strided(image.begin() + i, width), strided(image.end() + i, width));
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}
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// inverse wavelet transform in x-direction
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for(int i = 0; i < height; ++i){
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unwavelet(image.begin() + i*width, image.begin() + (i+1)*width);
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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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int zeros = 0;
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auto compressed_vec = decompress(compress(image_vec, width, 0.5, zeros));
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// output some information
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std::cout << field("raw") << human_string(image_vec.size()) << std::endl;
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std::cout << field("compressed") << human_string(image_vec.size() - zeros) << std::endl;
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// save to output file
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std::string cfilename = "compressed/" + path.filename().string();
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png::gray_ostream compressed_image(width, height, cfilename);
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for(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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