diffusion_quantization.hpp

#ifndef PASTELGFX_DIFFUSION_QUANTIZATION_HPP
#define PASTELGFX_DIFFUSION_QUANTIZATION_HPP

#include "pastel/gfx/quantization/diffusion_quantization.h"

namespace Pastel
{

    template <typename Vector>
    void quantizeErrorDiffusion(
        Array<Vector, 2>& image,
        const NoDeduction<Vector>& interval)
    {
        ENSURE(allGreater(interval, 0));

        integer width = image.width();
        integer height = image.height();

        Vector halfInterval(interval * 0.5);

        // By referring to floor without a namespace,
        // we make it possible to also find other
        // floor-functions such as the one for the
        // vectors.
        using std::floor;

        for (integer y = 0;y < height;++y)
        {
            for (integer x = 0;x < width;++x)
            {
                Vector value = image(x, y);
                Vector remainder = 
                    value - floor((value / interval)) * interval;
                Vector error = 
                    remainder - interval * (Vector)(remainder >= halfInterval);

                image(x, y) -= error;

                error /= 16;

                if (x < width - 1)
                {
                    image(x + 1, y) += 7 * error;
                }
                if (y < height - 1)
                {
                    if (x < width - 1)
                    {
                        image(x + 1, y + 1) += error;
                    }
                    image(x, y + 1) += 5 * error;
                }
                if (x > 0 && y < height - 1)
                {
                    image(x - 1, y + 1) += 3 * error;
                }
            }
        }
    }

}

#endif