Java I need help about how to get a pixel value in Java

Greetings!

Hey guys, I need help on how can I get pixel value of an image with pixels more than 100px (10x10).

Here the code that I execute in order to get the pixel value

Java:
try{
            File f = new File ("input image location");
            BufferedImage img = ImageIO.read(f);
        }catch(IOException e){
            System.out.println(e);
        }
      
        //get image width and height
        int width = img.getWidth();
        int height = img.getHeight();
        int count=0;
        for(int i=0; i<height; i++){
          
            for(int j=0; j<width; j++){
                count++;
                //get pixel value
                Color c = new Color(img.getRGB(j, i));
                int p = img.getRGB(j, i);
                //get alpha
                int a = (p >> 24) & 0xff;
                //get red
                int r = (p >>16) & 0xff;
                //get green
                int g = (p >> 8) & 0xff;
                //get blue
                int b = (p >>0) & 0xff;
                System.out.print("No. "+count);
                System.out.println("Value of Alpha: "+a+ " Value of Red: "+r+" Value of Green: "+g+" Value of Blue: "+b+"");
              
                p = (a<<24) | (r<<16) | (g<<8) | b;
                System.out.println("Value of Pixel in Binary Presentation"+p);
              
                img.setRGB(j, i, p);
              
               
              
                    try{
                    f = new File("output image location");
                    ImageIO.write(img, "png", f);
                  
                  }catch(IOException e){
                    System.out.println(e);
                  }
              
                } 
        }

Actually I've tried this code for an image with 100px (10x10). And the value that I've got is quite good. But if I try with an image more than 100px it will not produce any output.

The only output I receive as i attached below
as in the link here
Hope you guys can help me out. Thank you in advance
 
Last edited by a moderator:

Borg

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int p = img.getRGB(j, i);
It looks like you're building RGB values from the image position. Since RGB values have a finite max value, your code exceeds that value for larger images.
 
It looks like you're building RGB values from the image position. Since RGB values have a finite max value, your code exceeds that value for larger images.
Oh i see, so is there any alternative I can use to get the RGB values for a larger image that 100px? If you have any suggestion I could use
 

Borg

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If you still want to use the image position, you could use the remainder of a modulus check to set the values. That way it resets itself when it gets too big. Of course the colors will suddenly change on the screen where that happens.
 
If you still want to use the image position, you could use the remainder of a modulus check to set the values. That way it resets itself when it gets too big. Of course the colors will suddenly change on the screen where that happens.
Erm it's a bit blurry for me to understand. Can you clear me out using codes or references?
 

Borg

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Do you know what the modulus function is?
 
Do you know what the modulus function is?
Yup, I know how the modulus function works. But I don't know where to implement the modulus function in order to reset itself
 

Borg

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Right where I showed you that it was breaking. Instead of using i and j directly, replace those values with the modulus of i and the modulus of j.
 
Right where I showed you that it was breaking. Instead of using i and j directly, replace those values with the modulus of i and the modulus of j.
Oh I see, so after I do the looping, and just modulus the value of i and j before I want to getRGB(),
Java:
  for(int j=0; j<width; j++){
                count++;
                //get pixel value
                Color c = new Color(img.getRGB(j, i));
                int p = img.getRGB(j, i);
                //get alpha
                int a = (p >> 24) & 0xff;
                //get red
                int r = (p >>16) & 0xff;
                //get green
                int g = (p >> 8) & 0xff;
                //get blue
                int b = (p >>0) & 0xff;

is it right?
 

Borg

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Yes but where's your modulus?
 

Borg

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That's OK. You're here to learn. You're going to want to replace the values of i and j after the count++ line with new variables that are based on the modulus values of i and j. Does that make sense?
 
That's OK. You're here to learn. You're going to want to replace the values of i and j after the count++ line with new variables that are based on the modulus values of i and j. Does that make sense?

Yeah mate, I'm kinda new here. It kinda make sense to me. So should i do this?

Java:
   int k = i % j;
Erm.. does it work? Or it doesn't help at all?
 

Borg

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No, you want two new variables. For i, you want to 'modulate' the value to not exceed the max RGB value.
 
No, you want two new variables. For i, you want to 'modulate' the value to not exceed the max RGB value.
So i should modulus both variables with odd number or even number ? and it looks like this?

Code:
   int k = i % 2;
   int l = j % 2;
 

Borg

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Closer. Instead of 2, you want the max value for an RGB color.
 

Borg

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OK, good luck. I'm sure that you have what you need now.
 

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