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【画像処理100本ノック】独自の画像入出力クラスを作る

Q.16. Prewittフィルタ

Prewittフィルタ(3x3)を実装せよ。

これがプレウィットフィルタですか。

int main()
{
	PPM ppm("imori.pnm");
	int width = ppm.Get_width();
	int height = ppm.Get_height();
	PPM ppm2(width, height);

	auto kernel = [&](int i, int j)
	{
		double ret = 0;
		/*if (j == -1)
		{
			if (i == -1 || i == 1) ret = 1;
			else if (i == 0) ret = 1;
		}
		else if (j == 1)
		{
			if (i == -1 || i == 1) ret = -1;
			else if (i == 0) ret = -1;
		}*/
		if (i == -1)
		{
			if (j == -1 || j == 1) ret = 1;
			else if (j == 0) ret = 1;
		}
		else if (i == 1)
		{
			if (j == -1 || j == 1) ret = -1;
			else if (j == 0) ret = -1;
		}

		
		return ret;// / 16.;
	};

	auto conv = [&](const std::vector<std::vector<double>>& f)
	{
		std::vector < std::vector < double >> ret(width, std::vector<double>(height));
		for (int j = 0; j < height; j++)
			for (int i = 0; i < width; i++)
			{
				ret[i][j] = 0;
			}
		for (int j = 0; j < height; j++)
			for (int i = 0; i < width; i++)
			{
				int sum = 0;
				for (int di = -1; di <= 1; di++)
					for (int dj = -1; dj <= 1; dj++)
					{
						if (i - di >= 0 && i - di < width && j - dj >= 0 && j - di < height)
						{
							ret[i][j] += kernel(di, dj) * f[i - di][j - dj];
							sum += kernel(di, dj);
						}
					}
				//ret[i][j] /= (double)sum;
			}
		return ret;
	};

	std::vector < std::vector < double >> arry(width, std::vector<double>(height));
	for (int j = 0; j < height; j++)
		for (int i = 0; i < width; i++)
		{
			int r = ppm(i, j, 'r');
			int g = ppm(i, j, 'g');
			int b = ppm(i, j, 'b');
			int y = (std::round)(0.2126 * r + 0.7152 * g + 0.0722 * b);
			arry[i][j] = y;
		}
	arry = conv(arry);

	for (int j = 0; j < height; j++)
		for (int i = 0; i < width; i++)
		{
			int val = abs(arry[i][j]);
			if (val > 255) val = 255;
			ppm2(i, j, 'r') = val;
			ppm2(i, j, 'g') = val;
			ppm2(i, j, 'b') = val;

		}

	ppm2.Flush("out.ppm");
	return 0;
}