ImageChecker::write(unsigned char* data, size_t len)
{
    for (size_t i = 0; i < len; ++i)
    {
        size_t y = (this->offset + i) / width / stripesize;
        unsigned char color = get_pixel_color(n, y);
        if (data[i] != color)
        {
            okay = false;
        }
    }
    this->offset += len;
}
ImageChecker::write(unsigned char* data, size_t len)
{
    for (size_t i = 0; i < len; ++i)
    {
        size_t y = (this->offset + i) / width / stripesize;
        unsigned char color = get_pixel_color(n, y);
        if (data[i] != color)
        {
            okay = false;
        }
    }
    this->offset += len;
}