Yes, it has to do with the fact that processing stores it s colors as integers. So I changed your code a bit:

   PImage myImage;  // Declaration 
   
   void setup() {
     size(500, 500);
     myImage = loadImage("colorsample.png"); // Initialization
     noStroke();
   }

   void draw() 
   {
     background(0);
     image(myImage, 0, 0, width, height);
   
     // get color k
     color k = get(100, 100);
     float r_k = red(k); // get red component of k
     float g_k = green(k);// get green component of k
     float b_k = blue(k);// get blue component of k
   
     // print out k
     println("color k = color(" + r_k + ", " + g_k + ", " + b_k + ");");
     fill(r_k, g_k, b_k); // fill k
     rect(100, 100, 100, 100); // draw rect with k
   
     // get color c
     color c = get(300, 300);
     float r_c = red(c); // get red component of c
     float g_c = green(c);// get green component of c
     float b_c = blue(c);// get blue component of c
   
     // print out c
     println("color c = color(" + r_c + ", " + g_c + ", " + b_c + ");");
     fill(r_c, g_c, b_c); // fill c
     rect(300, 300, 100, 100);  // draw rect with c
   }