Hi, I am new to Processing, so please be easy on me :)

I don't even know if it's possible but I would like my Class to start at the pixel that is the closest to cyan (0,255,255) of my background image.
Is there a way I can do that?
I assume, I have to replace the x,y of my class starting point definition - How could this look like?
Thanks a lot!

This is where I'm at so far:

DLA[] dla;
int amount=1;
PImage img;

void setup() {
 size(1700,900,JAVA2D);
 img = loadImage("backgroundimage.jpg");
 background(img);
 loadPixels();

dla=new DLA[amount];
 
for(int i=0;i<amount;i++){
 dla[i]=new DLA(x,y,round(random(1,10)),round(random(1,10)),round(random(1,10)));
//I would like to insert the x,y of the cyan pixel here....
}
}

void draw() {
for(int i=0;i<amount;i++){  
 dla[i].aggregate();        
}
}

class DLA{
float[] pX, pY;

float startRadius = 10;
int maxP = 1000;
int pCount = 3;
float pSize = 6;
int stickDist = 9;  
int sx,sy;
float weight;  

DLA(int _sx, int _sy, int pCount, float pSize, int stickDist){
 sx=_sx;
 sy=_sy;
 pX = new float[maxP];
 pY = new float[maxP];
 pX[0] = 0;
 pY[0] = 0;  
 weight = 3;
}

void aggregate(){
   pushMatrix();
   strokeWeight( weight);

 float arrayDist, arraySize;
 float maxJumpDist = width;
 int closestElement = 0;
 translate(sx,sy);
 float theta = random(TWO_PI);
 float newElementX=startRadius*sin(theta);
 float newElementY=startRadius*cos(theta);
   
 while (true) {
   for (int i=0; i<pCount; i++) {
     arrayDist = dist(pX[i],pY[i],newElementX,newElementY);
     if (arrayDist<maxJumpDist) {
       maxJumpDist = arrayDist;
       closestElement = i;
     }
   }

   if (maxJumpDist<=stickDist) {
     theta = atan2(newElementY-pY[closestElement], newElementX-pX[closestElement]);
     pX[pCount] = pX[closestElement] + pSize*cos(theta);
     pY[pCount] = pY[closestElement] + pSize*sin(theta);
     stroke(255,150);    
     line(pX[pCount],pY[pCount],pX[closestElement],pY[closestElement]);  
     for (int i=0; i<pCount; i++) {
       arraySize = dist(pX[i],pY[i],0,0);
       if (arraySize>startRadius) {
         startRadius = arraySize;
       }
     }
     weight=weight*0.995;
     pCount++;
     if (pCount == maxP) {
       noLoop();
     }
     break;
   }

   theta = random(TWO_PI);
   newElementX+=random(maxJumpDist)*sin(theta);
   newElementY+=random(maxJumpDist)*cos(theta);
   if (dist(0,0,newElementX,newElementY)>startRadius*2) {
     newElementX=startRadius*sin(theta);
     newElementY=startRadius*cos(theta);
   }
 }
 popMatrix();
 }
 }

I don't have any mouse interaction...sorry, didn't solve my problem.

Anybody else???

Thanks for your response, Ramin.
This looks like the way to go. It also turns out to be way more complex than I thought. I am glad when I manage to piece code together but this one is a tough one for me ( ...did I mention, that I started with Processing and code in general just  this year ? )
It makes sense and all but I don't know how the result would have to look like.
How would I have to integrate it into the code above?

yes. i wanted to edit your code but somthing at the beginning made an exception and i dont know what the program should do, so i wrote this lines. like andrewowaun said . modify the method or write a new one that has PImage and a color as parameter and returns an PVector for the point in the image where the color is nearest to the parameter color.