# [C_AR161-易] PSNR計算
- [題目連結](https://e-tutor.itsa.org.tw/e-Tutor/mod/programming/view.php?id=29310)
- [峰值信噪比(Peak Signal o Noise Ratio, PSNR)](https://zh.wikipedia.org/wiki/%E5%B3%B0%E5%80%BC%E4%BF%A1%E5%99%AA%E6%AF%94)
- 公式(已修正原圖中數字8被錯置為6的問題)
- 範例(已修正範例2輸出結果)

## 程式碼(Java):

import java.util.*;

//[C_AR161-易] PSNR計算
//2019,12,29;19:18
public class Main {
	static Scanner sc = new Scanner(System.in);
	final static double x2peak = Math.pow(255, 2);

	public static void arrInput(int[][] arr) {
		for (int i = 0; i < arr.length; i++)
			for (int j = 0; j < arr[i].length; j++)
				arr[i][j] = sc.nextInt();
	}

	public static double getMSE(int[][] x, int[][] y) {
		double MSE = 0;
		for (int i = 0; i < x.length; i++) {
			for (int j = 0; j < x[i].length; j++)
				MSE += Math.pow(x[i][j] - y[i][j], 2);
		}
		return MSE / (x.length * x[0].length);
	}

	public static double getPSNR(double MSE) {
		double PSNR = 10 * (Math.log10(x2peak / MSE));
		return PSNR;
	}

	public static void main(String[] args) {
		int m = sc.nextInt();
		int n = sc.nextInt();
		int[][] pic_1 = new int[n][m];
		int[][] pic_2 = new int[n][m];
		arrInput(pic_1);
		arrInput(pic_2);
		double MSE = getMSE(pic_1, pic_2);
		if (MSE == 0)
			System.out.println("0.00 infinity");
		else {
			double PSNR = getPSNR(MSE);
			System.out.printf("%.3f %.3f\n", MSE, PSNR);
		}
	}
}

## 結果:
> [name=風思]
> 已修正題目本身提供的錯誤資訊，程式的部分，則善用Math類別，注意出輸入。
[](https://sites.google.com/s/15xXm2t0rfZvyJwO6DutZkT_6ZPtEUnuR/p/19D0GWbNFWSxtc0CVt2g4AFB9s8hlDpUc/edit)
###### tags: `e tutor` `黎明高中` `LMcps` `[C_AR161-易] PSNR計算`