使用java从图像中获取像素数据

我试图从64 x 48位图中获取像素rgb值.我得到了一些价值,但远不及3072 (= 64 x 48)我期待的价值.我也得到:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Coordinate out of bounds!
at sun.awt.image.ByteInterleavedRaster.getDataElements(ByteInterleavedRaster.java:301)
at java.awt.image.BufferedImage.getRGB(BufferedImage.java:871)
at imagetesting.Main.getPixelData(Main.java:45)
at imagetesting.Main.main(Main.java:27)

我找不到越界错误...

这是代码:

package imagetesting;

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



public class Main {

public static final String IMG = "matty.jpg";

public static void main(String[] args) {

    BufferedImage img;

    try {
        img = ImageIO.read(new File(IMG));

        int[][] pixelData = new int[img.getHeight() * img.getWidth()][3];
        int[] rgb;

        int counter = 0;
        for(int i = 0; i < img.getHeight(); i++){
            for(int j = 0; j < img.getWidth(); j++){
                rgb = getPixelData(img, i, j);

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

                counter++;
            }
        }


    } catch (IOException e) {
        e.printStackTrace();
    }

}

private static int[] getPixelData(BufferedImage img, int x, int y) {
int argb = img.getRGB(x, y);

int rgb[] = new int[] {
    (argb >> 16) & 0xff, //red
    (argb >>  8) & 0xff, //green
    (argb      ) & 0xff  //blue
};

System.out.println("rgb: " + rgb[0] + " " + rgb[1] + " " + rgb[2]);
return rgb;
}

}

John Kugelma.. 12

这个:

for(int i = 0; i < img.getHeight(); i++){
    for(int j = 0; j < img.getWidth(); j++){
        rgb = getPixelData(img, i, j);

与此不匹配:

private static int[] getPixelData(BufferedImage img, int x, int y) {

您已i计算行和j列,即i包含y值并j包含x值.那是倒退.

1> John Kugelma..：

---

这个:

for(int i = 0; i < img.getHeight(); i++){
    for(int j = 0; j < img.getWidth(); j++){
        rgb = getPixelData(img, i, j);

与此不匹配:

private static int[] getPixelData(BufferedImage img, int x, int y) {

您已i计算行和j列,即i包含y值并j包含x值.那是倒退.

---

我会将它们命名为"行"和"列",以便更加精确.y轴通常是倒置的(顶部>向下),这与我们习惯的xy坐标系不同.对于行和列,它更容易将图像视为矩阵,然后索引不是暧昧的.

2> davenpcj..：

---

我一直在寻找同样的能力.不想枚举整个图像,所以我做了一些搜索并使用了PixelGrabber.

Image img = Toolkit.getDefaultToolkit().createImage(filename);
PixelGrabber pg = new PixelGrabber(img, 0, 0, -1, -1, false);

pg.grabPixels(); // Throws InterruptedException

width = pg.getWidth();
height = pg.getHeight();

int[] pixels = (int[])pg.getPixels();

您可以int[]直接使用此处,像素采用ColorModel指定的格式pg.getColorModel(),或者您可以将false更改为true并强制它为RGB8-in-int.

我已经发现,Raster和类也可以这样做,并且已经添加了一些有用的类javax.imageio.*.

BufferedImage img = ImageIO.read(new File(filename)); // Throws IOException
int[] pixels = img.getRGB(0,0, img.getWidth(), img.getHeight, null, 0, img.getWidth());

// also available through the BufferedImage's Raster, in multiple formats.
Raster r = img.getData();
int[] pixels = r.getPixels(0,0,r.getWidth(), r.getHeight(), (int[])null);

还有几种getPixels(...)方法Raster.

3> 小智..：

---

这也有效:

BufferedImage img = ImageIO.read(file);

int[] pixels = ((DataBufferInt)img.getRaster().getDataBuffer()).getData();

---

这为我提供了类强制转换异常 - java.lang.ClassCastException:java.awt.image.DataBufferByte无法强制转换为java.awt.image.DataBufferInt

---

您不能盲目地将数据缓冲区转换为DataBufferInt,具体类型取决于原始类型(以及特定的解码器决策).