Question

所以基本上这是程序的一部分，它应该将图像的灰度值分别转换为下面的ascii代码，但是有错误说＆＃34;方法必须返回一种char [] [] ＆＃34;我成功完成了第一个（＆＃34;返回null＆＃34;），它打印了空格。

public static char[][] imageToASCII(Image img)
{
    BufferedImage bufImg = convert(img);
    for(int j=0; j<bufImg.getHeight(); j++)
    {
    for(int i=0; i<bufImg.getWidth(); i++)
    {

    int values=bufImg.getRGB(i,j);
    Color oldColor = new Color(values);
    int red = oldColor.getRed();        // get red value
    int green = oldColor.getGreen();    // get green value
    int blue = oldColor.getBlue();
    double grayVal = 0.299*red + 0.587*green + 0.114*blue;
    Color newColor = new Color((int)grayVal, (int)grayVal, (int)grayVal);


    if(grayVal >= 230)
    {
        return null;
    }
    else if(grayVal >= 200 && grayVal < 230)
    {
        return .;
    }
    else if(grayVal >= 180 && grayVal < 200)
    {
        return *;
    }
    else if(grayVal >= 160 && grayVal < 180)
    {   
        return :;
    }
    else if(grayVal >= 130 && grayVal < 160)
    {
        return o;
    }
    else if(grayVal >= 100 && grayVal < 130)
    {
        return &;
    }
    else if(grayVal >= 70 && grayVal < 100)
    {
        return 8;
    }
    else if(grayVal >=50 && grayVal < 70)
    {
        return #;
    }
    else
        return @

    }
    }



}}

Answer 1

首先，要返回一个char，你应该将它括在单引号中。其次，你实际上并不想要返回一个角色，而是将它设置在一个字符矩阵中。以下是对您的代码的修改：

import java.awt.image.BufferedImage;
import java.awt.Color;

public class Test {
  public static char[][] imageToASCII(BufferedImage img) {
    int w = img.getWidth();
    int h = img.getHeight();
    char[][] res = new char[h][w];

    for(int j=0; j<h; j++) {
      for(int i=0; i<w; i++) {
        int values = img.getRGB(i,j);
        Color oldColor = new Color(values);
        int red = oldColor.getRed();        // get red value
        int green = oldColor.getGreen();    // get green value
        int blue = oldColor.getBlue();
        double grayVal = 0.299*red + 0.587*green + 0.114*blue;

        if(grayVal >= 230) {
          res[j][i] = ' ';
        } else if(grayVal >= 200 && grayVal < 230) {
          res[j][i] = '.';
        } else if(grayVal >= 180 && grayVal < 200) {
          res[j][i] = '*';
        } else if(grayVal >= 160 && grayVal < 180) {
          res[j][i] = ':';
        } else if(grayVal >= 130 && grayVal < 160) {
          res[j][i] = 'o';
        } else if(grayVal >= 100 && grayVal < 130) {
          res[j][i] = '&';
        } else if(grayVal >= 70 && grayVal < 100) {
          res[j][i] = '8';
        } else if(grayVal >=50 && grayVal < 70) {
          res[j][i] = '#';
        } else {
          res[j][i] = '@';
        }
      }
    }
    return res;
  }
}

此外，此代码在性能方面效率非常低。对于W x H>的图像。 255，最好避免顺序ifs。这可以通过在初始化时创建一个数组来完成，该数组将每个可能的灰度值映射到相应的char，然后在循环遍历图像时解除引用这样的数组：

import java.awt.image.BufferedImage;
import java.awt.Color;

public class Test {
  private static char[] map;

  private static void initMap() {
    map = new char[256];
    int[][] ranges = new int[][] {
      {0, 50}, {50, 70}, {70, 100}, {100, 130},
      {130, 160}, {160, 180}, {180, 200},
      {200, 230}, {230, 256}
    };
    char[] v = {' ', '#', '8', '&', 'o', ':', '*', '.', ' '};
    for(int i=0; i<v.length; i++) {
      for(int j=ranges[i][0]; j < ranges[i][1]; j++) {
        map[j] = v[i];
      }
    }
  }

  public static char[][] imageToASCII(BufferedImage img) {
    if (map == null) {
      initMap();
    }
    int w = img.getWidth();
    int h = img.getHeight();
    char[][] res = new char[h][w];

    for(int j=0; j<h; j++) {
      for(int i=0; i<w; i++) {
        int values = img.getRGB(i,j);
        Color oldColor = new Color(values);
        int red = oldColor.getRed();        // get red value
        int green = oldColor.getGreen();    // get green value
        int blue = oldColor.getBlue();
        int grayVal = (int)(0.299*red + 0.587*green + 0.114*blue);
        if (grayVal > 255) {
          grayVal = 255;
         }
        res[j][i] = map[grayVal];
      }
    }
    return res;
  }
}

Answer 2

这是一个课程，向您展示应该返回的内容的结构，以及如何在控制台中显示它：

package stackOverflow;

public class ImageToGrayscale
{
    public static void main(String[] args) {
        char[][] image = return2DChars(30, 10);
        for (int i = 0; i < image.length; i++) {
            char[] row = image[i];
            for (int j = 0; j < row.length; j++) {
                System.out.print(row[j]);
            }
            System.out.println();
        }
    }

    public static char[][] return2DChars(int width, int height) {
        char[][] image = new char[height][width];
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                image[i][j] = (Math.random() < 0.5) ? ':' : '#';
            }
        }
        return image;
    }
}

输出：

#:#:###:::::#:#::#:::##:#::###
####:#::###:::#:###:##:::#::##
##:#:##:##:::#:##::#:###::::::
:::#:::###:#::########:#::##:#
:#::#:####:::#::#:::##::#:#:::
####::####:#:::##:##::::::####
::####:##::#:#::::#::#:#:#::#:
#::###::##:::####:::#:#:##::##
#:####::::#####:#####::###:###
::##:#:###:#:::#::####:::##:#:

使用grayVal转换为Ascii字符将图像转换为Ascii代码

2 个答案: