Question

我是Java编程的初学者。我有算法，但我很难编码。我想比较RGB十六进制像素值的第2和第4位的2个相似图像，以检查其中一个图像的像素值是否与另一个不同。

我的算法逻辑：

if(image1.substring2 == image2.substring2) && (image1.substring4 == image2.substring4)，像素相同。
if(image1.substring2 != image2.substring2) || (image1.substring4 != image2.substring4)，像素不一样。
if(image1.substring2 != image2.substring2) && (image1.substring4 != image2.substring4)，像素不一样。

我这里有其余的代码。我尝试将所有过程分开，以便以后进行故障排除。

// MAIN

public class getPixelRGB1
  {
private static int a;
private static int r;
private static int g;
private static int b;
private static final double bitPerColor = 4.0;


public static void main(String[] args) throws IOException
{
    FileInputStream image = null;
    FileInputStream image2 = null;

    getPixelData1 newPD = new getPixelData1();

    try {
        BufferedImage img, img2;

        File file = new File("img0.jpg");
        File file2 = new File("imgstega.jpg");
        image = new FileInputStream(file);
        image2 = new FileInputStream(file2);
        img = ImageIO.read(image);
        img2 = ImageIO.read(image2);

        int rowcol;
        int width = img.getWidth();
        int height = img.getHeight();
        System.out.println("Image's Width: " + width);
        System.out.println("Image's Height: " + height);

        int[][] pixelData = new int[width * height][3];

        System.out.println("Pixel Data: " + pixelData);

        int[] rgb;
        int count = 0;

        for(int i=0; i<width; i++)
        {
            for(int j=0; j<height; j++)
            {
                rgb = newPD.getPixelData(img, i, j);

                for(int k = 0; k < rgb.length; k++)
                {
                    pixelData[count][k] = rgb[k];

                }
                count++;
                System.out.println("\nRGB Counts: " + count);
            }
        }

        int width2 = img2.getWidth();
        int height2 = img2.getHeight();
        System.out.println("Image's Width: " + width2);
        System.out.println("Image's Height: " + height2);

        int[][] pixelData2 = new int[width2 * height2][3];

        int[] rgb2;
        int counter = 0;

        for(int i=0; i<width2; i++)
        {
        for(int j=0; j<height2; j++)
        {
        rgb2 = newPD.getPixelData(img2, i, j);

        for(int k = 0; k < rgb2.length; k++)
        {
        pixelData2[counter][k] = rgb2[k];

        }
        counter++;
        System.out.println("\nRGB2 Counts: " + counter);
        }
        }

    } catch (FileNotFoundException ex) {
        Logger.getLogger(getPixelRGB1.class.getName()).log(Level.SEVERE, null, ex);
    } finally {
        try {
            image.close();
        } catch (IOException ex) {
            Logger.getLogger(getPixelRGB1.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

}  
}

// 1ST PROCESS - 获取RGB像素值

public class getPixelData1 
{
private static final double bitPerColor = 4.0;

public int[] getPixelData(BufferedImage img, int w, int h) throws IOException
{
    int argb = img.getRGB(w, h);
    int rgb[] = new int[]
    {
        (argb >> 16) & 0xff, //red
        (argb >>  8) & 0xff, //green
        (argb      ) & 0xff  //blue
    };

    int red = rgb[0];
    int green = rgb[1]; //RGB Value in Decimal
    int blue = rgb[2];

    System.out.println("\nRGBValue in Decimal --> " + "\nRed: " + red + " Green: " + green + " Blue: " + blue);

    //Convert each channel RGB to Hexadecimal value
    String rHex = Integer.toHexString((int)(red));
    String gHex = Integer.toHexString((int)(green));
    String bHex = Integer.toHexString((int)(blue));

    System.out.println("\nRGBValue in Hexa --> " + "\nRed Green Blue " + rHex + gHex + bHex);

    //Check position 2 and 4 of hexa value for any changes
    String hexa2, hexa4 = "";
    String rgbHexa = rHex + gHex + bHex;

    hexa2 = rgbHexa.substring(1,2);
    System.out.println("\nString RGB Hexa: " + rgbHexa);
    System.out.println("\nSubstring at position 2: " + hexa2);

    String hex = String.format("%02X%02X%02X", red, green, blue);
    hexa4 = hex.substring(3,4);
    System.out.println("\nSubstring at position 4: " + hexa4);

    return rgb;
}
}

// 2nd Process - 比较两个图像的RGB Hex值

public class compareHexaRGB
{
public int[] compareHexaRGB(BufferedImage img, BufferedImage img2, int w, int h) throws IOException
{
    getPixelData1 newPD = new getPixelData1(); //get method from class getPixelData1 - is this correct?

            if((img.hexa2.equals(img2.hexa2)) && (img.hexa4.equals(img2.hexa4))) 
              {
                   System.out.println("Pixel values at position 2 and 4 are the same.");
              }
            else if((img.hexa2 != img2.hexa2) || (img.hexa4 != img2.hexa4))
              {
                  System.out.println("Pixel values at position 2 and 4 are not the same.");
              }
            else if((img.hexa2 != img2.hexa2) && (img.hexa4 != img2.hexa4))
              {
                  System.out.println("Pixel values at position 2 and 4 are not the same.");
              }
}
}

错误表明程序无法在bufferedImage中找到hexa2和hexa4的符号。有人可以检查我的编码是否在这里做错了吗？我还是Java新手。

Answer 1

img的类型为BufferedImage（javadoc）。它不包含任何名为hexa2或hexa4的非私有（也称为私有）字段。

您需要做的是重构您的代码，以确保您可以在compareHexaRGB()中访问它们。可能有很多方法可以做到这一点。也许您可以扩展BufferedImage以包含您的字段，或者您可以将它们作为输入传递给方法。

考虑到我们并没有真正拥有所有代码（例如，我根本没有看到compareHexaRGB()被调用），哪个更优雅的解决方案很难确定。

更准确地说一下编译问题：通过使用img.hexa2访问字段，您可以假设hexa2中有一个名为BufferedImage的字段，可以从您的班级访问。例如，如果某个字段声明为public，则为true。更典型的是，字段为private范围，需要由getter / setter访问。对于BufferedImage，根本不存在此类字段。

了解访问控制here。

错误表明程序找不到hexa2和hexa4的符号

1 个答案: