Question

我看到一个关于将BufferedImage转换为像素/字节数组的线程。直接在图像上使用getRGB可以正常工作，但不太理想，因为它太慢而无法收集所有像素。我尝试了另一种简单抓取像素数据的方法。

    //convert canvas to bufferedimage
    BufferedImage img = new BufferedImage(500, 500, BufferedImage.TYPE_3BYTE_BGR);
    Graphics2D g2 = img.createGraphics();
    canvas.printAll(g2);
    g2.dispose();

    System.out.println(img.getRGB(0, 0));    //-16777216 works but not ideal

    byte[] pixels = ((DataBufferByte) img.getRaster().getDataBuffer()).getData();
    for(byte b : pixels){
        System.out.println(b);    //all 0 doesnt work
    }

但是，整个字节数组似乎是空的（用0填充）。

Answer 1

我不知道代码中canvas的含义，但这完全有效：

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferByte;

public class Px {

    public static void main(String[] args) {
        new Px().go();
    }

    private void go() {
        BufferedImage img = new BufferedImage(5, 5, BufferedImage.TYPE_3BYTE_BGR);
        Graphics2D g2 = img.createGraphics();
        g2.setColor(Color.red);
        g2.fillRect(0, 0, 2, 2);
        g2.dispose();

        byte[] pixels = ((DataBufferByte) img.getRaster().getDataBuffer()).getData();
        for (byte b : pixels) {
            System.out.print(b + ",");
        }
    }
}

结果如下：

0,0,-1,0,0,-1,0,0,0,0,0,0,0,0,0,0,0,-1,0,0,-1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

颜色顺序为蓝绿红色。所以我的红色矩形在0,0，-1,0,0，-1等字节中显示为字节。我假设-1与255“相同”。

您可以探索自己的行canvas.printAll(）。也许画布只包含黑色像素。

Java BufferedImage到像素数组

1 个答案: