hello, im trying to change the colors and alpha value of  pixels of an image, first it analyzes a pic and based on a luminosity threshold it changes the colors and alpha value of the pixel, im using color with 4 values for changing the alpha value the 3 first ones are supposed to be the colors and the last one the alpha, but it doesnt work, Is there a special way to do this?
img.pixels[y] = color(0, 70, 0, 250);



here is the complete code:


int x;

PImage img;
PImage imgdos;
PImage imgtres;

color luminosidad;
float luminosidad_total;

color [] imagenn ;

float sube = 1;

void setup () {
 noStroke() ;
 strokeWeight(2) ;
 size (400, 400) ;
 img = loadImage("glitch.jpg");
 imgdos = loadImage("glitch.jpg");    
 imgtres = loadImage("glitch.jpg");
 
 loadPixels();
       
  for (int y = 0; y<img.height * img.width ;y++){
 luminosidad =  img.pixels[y];
 luminosidad_total =( ((red(luminosidad)) + (green(luminosidad)) + (blue(luminosidad)))/3);
       if(luminosidad_total<214){
             img.pixels[y] = color(0, 70, 0, 250);
       }
   
    if(luminosidad_total>124){
         imgdos.pixels[y] = color(80, 30, 0, 0);
        }
       
      if(luminosidad_total<184){
            imgtres.pixels[y] = color(0, 0, 0, 0);
           }
           }
updatePixels();

}
void draw()
{
 background(233) ;
 
x = x+ 1;
   image(img, 20, 10);
image(imgdos, x, 90);  
image(imgtres, 80, 180);
}