Function equalize

src-core/common/image/processing.cpp:175–214

    }

    void equalize(Image &img, bool per_channel)
    {
        for (int c = 0; c < (per_channel ? img.channels() : 1); c++)
        {
            if (c == 3) // Do not individual equalize alpha channel
                break;

            const int nlevels = img.maxval() + 1;
            size_t size = img.width() * img.height() * (per_channel ? 1 : img.channels());

            // Init histogram buffer
            int *histogram = new int[nlevels];
            for (int i = 0; i < nlevels; i++)
                histogram[i] = 0;

            // Compute histogram
            for (size_t px = 0; px < size; px++)
                histogram[img.get(c, px)]++;

            // Cummulative histogram
            int *cummulative_histogram = new int[nlevels];
            cummulative_histogram[0] = histogram[0];
            for (int i = 1; i < nlevels; i++)
                cummulative_histogram[i] = histogram[i] + cummulative_histogram[i - 1];

            // Scaling
            int *scaling = new int[nlevels];
            for (int i = 0; i < nlevels; i++)
                scaling[i] = round(cummulative_histogram[i] * (float(nlevels - 1) / size));

            // Apply
            for (size_t px = 0; px < size; px++)
                img.set(c, px, img.clamp(scaling[img.get(c, px)]));

            // Cleanup
            delete[] cummulative_histogram;
            delete[] scaling;
            delete[] histogram;
        }
    }

    void normalize(Image &img)
    {