[英]How to convert int RGB into BYTE 2D array gray image
我正在嘗試將彩色圖像轉換為灰度縮放圖像並將其作為BYTE值保存到2D陣列中,之后我需要在此2D陣列上執行一些處理。 雖然,我的數組的值都是字節,但我的輸出圖像變為藍色而不是灰色。 有人可以幫我嗎? 這是我的代碼:
public class HW {
public static void main(String[] args) {
int[][] savedImage = readimage(new File("C:\\Images\\input.jpg"));
BufferedImage grayImage = new BufferedImage(savedImage.length, savedImage[0].length, BufferedImage.TYPE_INT_RGB);
for (int i =0 ; i<savedImage.length ; i ++){
for (int j=0 ; j<savedImage[0].length ; j++){
grayImage.setRGB(i, j, savedImage[i][j]);
System.out.print(savedImage[i][j] + ",");
}
System.out.println();
}
try {
File outputfile = new File ("C:\\Images\\garyoutput.jpg");
ImageIO.write(grayImage, "jpg", outputfile);
}
catch(IOException e ) {
e.printStackTrace();
}
}
public static int[][] readimage(File filename) throws IOException {
// Grayscale Image output
BufferedImage img = ImageIO.read(filename);
int width = img.getWidth();
int height = img.getHeight();
int [][] readimageVal = new int [width][height];
for (int i = 0; i<height ; i++) {
for (int j =0 ; j<width ; j++) {
int p = img.getRGB(j,i);
int r = (p>>16)&0xff;
int g = (p>>8)&0xff;
int b = p&0xff;
int avg = ((r+b+g)/3);
readimageVal[j][i] = avg;
}
}
return readimageVal;
}
}
問題出在main
方法的主要嵌套循環中:
for (int i =0 ; i<savedImage.length ; i ++){
for (int j=0 ; j<savedImage[0].length ; j++){
grayImage.setRGB(i, j, savedImage[i][j]);//← Here
System.out.print(savedImage[i][j] + ",");
}
}
int[][] savedImage
包含一個表示灰度值的字節,但grayImage
仍然是BufferedImage.TYPE_INT_RGB
類型。 因此,如果您只調用grayImage.setRGB(i, j, savedImage[i][j])
,則只會設置int
的藍色部分:
RRRRRRRR GGGGGGGG BBBBBBBB
00000000 00000000 xxxxxxxx
所以你需要改為調用它:
int rgb = savedImage[i][j];
rgb = (rgb<<16)|(rgb<<8)|(rgb);
grayImage.setRGB(i, j, rgb);
您有不同的可能性,但首先,這是一種更簡單的方法來訪問像素:
public static int[][] readimage(File filename) throws IOException {
BufferedImage img = ImageIO.read(filename) ;// Grayscale Image output
final int width = img.getWidth() ;
final int height = img.getHeight() ;
int[][] graylevelarray = new int[height][width] ;
for (int y=0 ; y < height ; y++)
for (int x=0 ; x < width ; x++) {
int r = img.getRaster().getSample(x, y, 0) ;
int g = img.getRaster().getSample(x, y, 1) ;
int b = img.getRaster().getSample(x, y, 2) ;
graylevelarray[y][x] = ??? ;
}
return graylevelarray ;
}
正如我所說,對於轉換,您有許多不同的可能性:
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