Create an image from a 2D array

Question

I have a 2D array with dimensions [10][5] that I am trying to convert into an image. This is the code that I have tried, but it doesn't seem to be saving the image. What am I doing wrong?

public class GrayScale {

   BufferedImage  image;
   int width;
   int height;

   public GrayScale() {

       try {
          int[][] yourmatrix = new int[][]{
             { 0,  1, 0, 0, 234,  0, 0,   0, 0, 1 },
             { 0,  0, 0, 1,   0,  0, 1,   0, 0, 0 },
             { 0, 45, 0, 0,   0,  0, 0, 231, 0, 0 },
             { 0,  0, 0, 1,   0,  0, 1,   0, 0, 0 },
             { 0,  1, 0, 0,   0, 89, 0,   0, 0, 1 }
          };    

          width = yourmatrix.length;
          height = yourmatrix[0].length;

          for(int i=0; i<height; i++){

             for(int j=0; j<width; j++){
                 int u = yourmatrix[i][j];

                 image.setRGB(j,i,u);
             }
          }

          File ouptut = new File("C:\\Users\\Pratik\\Desktop\\UPWORK\\JAVA\\grayscale.jpg");
          ImageIO.write(image, "jpg", ouptut);

       } catch (Exception e) {}
    }


   static public void main(String args[]) throws Exception{
      GrayScale obj = new GrayScale();
   }
}

Your best bet would be to add a e.printStackTrace(); inside your catch(Exception e){} block and let us know what it prints out — CraigR8806
– CraigR8806, Commented Aug 7, 2017 at 12:37
To expand the above comment: Never ever have a Pokemon Catch (catches all exceptions) with an empty catch block. Never. — RealSkeptic
– RealSkeptic, Commented Aug 7, 2017 at 12:58

user7308827 · Accepted Answer · 2017-08-07 13:29:21Z

1

You must initialize your BufferedImage after initializing the width and height:

image = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_GRAY);

The image type can vary but since the constructor's name is GrayScale, I thought you would want TYPE_BYTE_GRAY.

answered Aug 7, 2017 at 13:29

user7308827

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1 Comment

PRATIK I PANCHAL Over a year ago

For color which constructor used?

Aman · Accepted Answer · 2017-08-08 09:11:13Z

Working example:

public class GrayScale {
    int width;
    int height;
    BufferedImage  image;

    GrayScale() {

       try {
          int[][] yourmatrix = new int[][]{
             { 0,  1, 0, 0, 234,  0, 0,   0, 0, 1 },
             { 0,  0, 0, 1,   0,  0, 1,   0, 0, 0 },
             { 0, 45, 0, 0,   0,  0, 0, 231, 0, 0 },
             { 0,  0, 0, 1,   0,  0, 1,   0, 0, 0 },
             { 0,  1, 0, 0,   0, 89, 0,   0, 0, 1 }
          };    

          width = yourmatrix[0].length;
          height = yourmatrix.length;

          image = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_GRAY);

          for(int i=0; i<height; i++){

             for(int j=0; j<width; j++){
                 int u = yourmatrix[i][j];

                 image.setRGB(j,i,u);
             }
          }

          File ouptut = new File("C:\\Others\\grayscale.jpg");
          ImageIO.write(image, "jpg", ouptut);

       }
       catch (Exception e)
       {
       }
    }
}

Corrections:
1. Width and height components are rearranged
2. "image" object defined on the correct place

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