Working with PNG files in C++
I’m working on MacOS X, so first of all I need to compile and install the libraries (libpng and png++):
#Download here: http://prdownloads.sourceforge.net/libpng/libpng-1.5.7.tar.gz?download tar xvzf libpng-1.5.7.tar.gz cd libpng-1.5.7 ./configure make sudo make install #Download png++ curl http://download.savannah.nongnu.org/releases/pngpp/png++-0.2.5.tar.gz > ./png++.tar.gz tar xzvf png++.tar.gz cd png++-0.2.5 make sudo make install
Everything should be installed now, and we can write some code. Create the following C++ program:
#include <png++/png.hpp>
int main() {
png::image< png::rgb_pixel > image("input.png");
for (size_t y = 0; y < image.get_height(); ++y) {
for (size_t x = 0; x < image.get_width(); ++x) {
if(((x+y)%2) == 0) image[x][y] = png::rgb_pixel(0, 0, 0);
}
}
image.write("output.png");
}
The program loads a file called input.png, sets every other pixel to black and writes it to output.png. Compile and run as follows:
g++ test.cpp -lpng ./a.out
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