将灰度图像读入一维数组

Question

我编写了以下代码来将灰度图像的像素读取到一维数组。 运行代码时我怎么会出错

 public class LoadImage {
   BufferedImage image;
   void load()throws Exception { 
     File input = new File("lena.png");
     image = ImageIO.read(input);
   }
   public Dimension getImageSize() {
     return new Dimension(image.getWidth(), image.getHeight());
   }

   public int[] getImagePixels() {
     int [] dummy = null;
     int wid, hgt;

     // compute size of the array
     wid = image.getWidth();
     hgt = image.getHeight();

     // start getting the pixels
     Raster pixelData;
     pixelData = image.getData();
     return pixelData.getPixels(0, 0, wid, hgt, dummy);
   }
 }

主类

 public static void main(String[] args) throws IOException, Exception {
   LoadImage l = new LoadImage();
   l.load();
   int pixel[];
   pixel= l.getImagePixels();
 }

Answer 1

好的，当您传递 File 对象时，问题来自 ImageIO.read 中的格式检测。试试这个：

import java.awt.Dimension;
import java.awt.image.BufferedImage;
import java.awt.image.Raster;
import java.io.IOException;
import javax.imageio.ImageIO;

public class LoadImage {
  BufferedImage image;
  void load() throws Exception { 
    image = ImageIO.read(getClass().getResourceAsStream("lena.png"));
  }

  public Dimension getImageSize() {
    return new Dimension(image.getWidth(), image.getHeight());
  }

  public int[] getImagePixels() {
    int [] dummy = null;
    int wid, hgt;

    // compute size of the array
    wid = image.getWidth();
    hgt = image.getHeight();

    // start getting the pixels
    Raster pixelData;
    pixelData = image.getData();

    System.out.println("wid:"+ wid);
    System.out.println("hgt:"+ hgt);
    System.out.println("Channels:"+pixelData.getNumDataElements());
    return pixelData.getPixels(0, 0, wid, hgt, dummy);
  }

  public static void main(String[] args) throws IOException, Exception {
    LoadImage l = new LoadImage();
    l.load();
    int[] pixel;
    pixel= l.getImagePixels();
    System.out.println("length:"+pixel.length);

    int height = 482;
    int width = 372;
    int channels = 3;
    int color = 0;

    BufferedImage red = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
    BufferedImage green = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
    BufferedImage blue = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);

    for (int y = 0; y < height; y++) {
      for (int x = 0; x < width; x++) {
        blue.setRGB(x, y, pixel[color * channels]);
        green.setRGB(x, y, pixel[color * channels + 1] << 8);
        red.setRGB(x, y, pixel[color * channels + 2] << 16);
        color++;
      }
    }
    ImageIO.write(red, "png", new File("red.png"));
    ImageIO.write(green, "png", new File("green.png"));
    ImageIO.write(blue, "png", new File("blue.png"));
  }
}

当我传递一个 372x482（24 位（3 通道）颜色）的 PNG 时，我得到了

wid:372
hgt:482
Channels:3
length:537912

使用更新后的代码，这就是您可以获取它返回的数组并将每个通道保存回文件的方法。