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Wannabree

•Created by Wannabree on 4/13/2025 in #java-help

LUT get index from .txt file

Hello, beginner here. In class we're currently working with OpenCV for image manipulation. We're asked to create a LookUpTable as a .txt file and and change the color of some pixels in an image. the .txt file is something like this:

000 255 000
255 000 000
000 000 255
255 255 255

000 255 000
255 000 000
000 000 255
255 255 255

I know that I can use a Scanner to read the values etc. but let's assume i just want the value 255 from col3 row3. Is there a direct way to access that value or do it have to loop through each line/value until i get to that point? I tried using FileReader and BufferReader but I haven't found way to read a specific value. My inital idea was it to read every value in the LUT and create an array so i don't have to loop through the whole table to get a single entry but that kind of destroys the purpose of a LUT. TL;DR is there a way to call a specific index from the LUT using only a .txt file?

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•Created by Wannabree on 4/8/2025 in #java-help

Call method from different class in a different package (beginner)

Hello, i have the following Problem: I have a class Histogramm.java inside a package Basis And my Main.java inside the package Main Histogramm.java has a function i want to call from Main.java

package Basis; 
 
import java.util.*; 
import org.opencv.core.*; 
import org.opencv.highgui.HighGui; 
import org.opencv.imgproc.Imgproc; 
import Main.Aufgaben02;
 
public class Histogramm { 

     //other methods etc
    
     public int[] gibHistogrammDaten(Mat bildMatrix) {
     int[] histogramm = new int[256];
     for(int i = 0; i<bildMatrix.rows();i++) {
         for(int j = 0; j<bildMatrix.cols(); j++) {
             double[] temp = bildMatrix.get(i,j);
             histogramm[(int)temp[0]]++;
         }
     }
     return histogramm;
   }
}

package Basis; 
 
import java.util.*; 
import org.opencv.core.*; 
import org.opencv.highgui.HighGui; 
import org.opencv.imgproc.Imgproc; 
import Main.Aufgaben02;
 
public class Histogramm { 

     //other methods etc
    
     public int[] gibHistogrammDaten(Mat bildMatrix) {
     int[] histogramm = new int[256];
     for(int i = 0; i<bildMatrix.rows();i++) {
         for(int j = 0; j<bildMatrix.cols(); j++) {
             double[] temp = bildMatrix.get(i,j);
             histogramm[(int)temp[0]]++;
         }
     }
     return histogramm;
   }
}

in my Main.java file i have a a Matrix that i want to pass to the gibHistogrammDaten(Mat bildMatrix) method.

package Main;

import org.opencv.core.*;
import org.opencv.imgcodecs.Imgcodecs;
import Basis.Histogramm.*;

import java.util.*;

import Basis.Bild;

public class Aufgaben02 {

    public static void main(String[] args) {
        
        //more code not relevant to the question
        
        Histogramm lel = new Histogramm();
        Mat hilfeOne = Imgcodecs.imread("Bilder/Blume.jpg", Imgcodecs.IMREAD_UNCHANGED);
    int[] histogramm = new int[256];
}

package Main;

import org.opencv.core.*;
import org.opencv.imgcodecs.Imgcodecs;
import Basis.Histogramm.*;

import java.util.*;

import Basis.Bild;

public class Aufgaben02 {

    public static void main(String[] args) {
        
        //more code not relevant to the question
        
        Histogramm lel = new Histogramm();
        Mat hilfeOne = Imgcodecs.imread("Bilder/Blume.jpg", Imgcodecs.IMREAD_UNCHANGED);
    int[] histogramm = new int[256];
}

I've been trying to call that method for a couple hours now. I tried setting the method to static public static int[] gibHistogrammDaten(Mat bildMatrix) which didn't work. I also tried creating an object of Histogramm lel = new Histogramm(); to go the route of int[] histogramm = lel.gibHistogrammDaten(hilfeOne); but that didn't work either. Next try was

int[] histogramm = new int[256];
histogram = gibHistogrammDaten(hilfeOne);

int[] histogramm = new int[256];
histogram = gibHistogrammDaten(hilfeOne);

which just tells me "The method gibHistogrammDaten(Mat) is undefined for the type Aufgaben02" Pretty much every answer i've found on google didn't work.

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