Usage

Installation

Copy pnm.hpp to your favorite location. Because pnm is a header-only, you need no build before use it.

example

#include <pnm++/pnm.hpp>
#include <iostream>

int main()
{
    using namespace pnm::literals; // ""_rgb literal

    pnm::image<pnm::rgb_pixel> ppm = pnm::read("sample.ppm");

    // you can get a number of pixels in the image
    std::cout << "width  = " << ppm.width()  << std::endl;
    std::cout << "height = " << ppm.height() << std::endl;

    // fill the image with 0xFF00FF.
    for(std::size_t y=0; y<ppm.y_size(); ++y)
    {
        for(std::size_t x=0; x<ppm.x_size(); ++x)
        {
            ppm[y][x] = 0xFF00FF_rgb;
        }
    }

    // write the image into `out.ppm` as binary format (after conversion)
    pnm::write("out.ppm", ppm, pnm::format::binary);

    return 0;
}

Pixel types

pnm supports 3 pixel types that correspond binary, grayscale, and RGB color.

binary and grayscale pixel type has a member variable value. RGB pixel type has 3 member variables named red, blue, and green, respectively.

pnm::bit_pixel binary;
binary.value = true;

pnm::gray_pixel gray;
gray.value = 0xFF;

pnm::rgb_pixel RGB;
RGB.red   = 0xFF;
RGB.green = 0xFF;
RGB.blue  = 0xFF;

Image types

pnm::image is a class that represents image. It requires pixel format as a template parameter.

pnm::image<pnm::bit_pixel>  ppm;
pnm::image<pnm::gray_pixel> ppm;
pnm::image<pnm::rgb_pixel>  ppm;

You can access each pixel by using operator[] and at() in the same way as nested vector. Also, you can access to lines composed by pixels by lines().

pnm::image<pnm::rgb_pixel> img;
for(const auto line : img.lines())
{
    for(const auto pixel : line)
    {
        std::cout << '(' << pixel.red  << ' ' << pixel.green << ' '
                         << pixel.blue << ')';
    }
}

The constructors accepts (width, height), (width, height, pixel), (width, height, std::vector<pixel>), and (std::vector<std::vector<pixel>>).

IO

read() and read_(pbm|pgm|ppm) functions read a file header and automatically detects the file format. read() function receives pixel_type that you want to get(By default, it is rgb_pixel).

Note that when you pass a pixel_type that is different from actual one contained in the file, read() converts the pixel_type if it is not narrowing-conversion (for example, conversion from bit_pixel to rgb_pixel is allowed. On the other hand, the opposite conversion is not allowed).

write function writes the image file into a specific file. You can select a format to write out by passing an enum value pnm::format::ascii or pnm::format::binary.