我想将图像像素存储在三维数组中,我的确如下:
public class ImageProcessing {
private BufferedImage image;
int p = image.getWidth();
int q = image.getHeight();
int r = 3;
private int[][][] data = new int[p][q][r];
然后我从该图像中获取像素值并将其存储到该数组中,并按如下方式构建构造函数:
public ImageProcessing(BufferedImage img){
image = img;
for(int x = 0; x < image.getWidth(); x++){
for(int y = 0; y < image.getHeight(); y++){
int px = image.getRGB(x,y);
int alpha = (px >> 24) & 0xFF;
int red = (px >> 16) & 0xFF;
int green = (px >> 8) & 0xFF;
int blue = px & 0xFF;
data[x][y][0] = alpha;
data[x][y][1] = red;
data[x][y][2] = green;
data[x][y][3] = blue;
}
}
}
然后我想检索它以将图像转换为灰度,如下所示:
public BufferedImage greyscale(){
for(int x = 0; x < p ; x++){
for(int y = 0; y < q ; y++){
int avg = (data[x][y][1] + data[x][y][2] + data[x][y][3]/3);
int grey = (data[x][y][0]<<24) + (avg<<16) + (avg<<8) + avg;
image.setRGB(x, y, grey);
}
}
return image;
}
但是当我运行它时,我会显示如下错误我不知道它意味着什么以及如何解决它?
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at ImageProcessing.<init>(ImageProcessing.java:6)
at Main$1.run(Main.java:14)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
如何解决?有什么想法吗?
答案 0 :(得分:2)
显然,这将是因为,
private BufferedImage image; // had not initialized image
int p = image.getWidth(); // will be null
int q = image.getHeight(); // same here
int r = 3;
private int[][][] data = new int[p][q][r];
您尚未初始化BufferedImage image
因此,它当前将指向null,当您初始化p = image.getWidth();
和int q = image.getHeight();
时,则没有任何值,因此
private int[][][] data = new int[p][q][r];
以上陈述将抛出NE
。
您应该在Class中声明数组,并且应该在类的构造函数中初始化它,并初始化image
。
编辑:
查看下面的代码,初始化BufferedImage
然后再做同样的事情,并且工作正常!!
public class ArrayInitialize {
public static void main(String ar[]){
File file = new File("Image.jpg");
BufferedImage img = new BufferedImage(240, 240, BufferedImage.TYPE_INT_ARGB);
try {
img = ImageIO.read(file);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
int p = img.getWidth(); // will be null
int q = img.getHeight(); // same here
int r = 3;
int count = 0;
int[][][] data = new int[p][q][r];
for(int i=0;i<p;i++){
for(int j=0;j<q;j++){
for(int k=0;k<r;k++){
count++;
}
}
}
System.out.println(count);
}
}
我认为,在初始化BufferedImage
后,如果您获得NullPointerException
,那么您的getImage()
方法存在一些问题,可能是因为它无法正常工作。
并参见评论
int r = 3应该是int r = 4不是吗。每种颜色都有4个组成部分。