How can I get the RGB/Greyscale value fro a single pixel - processing

Question

I'm creating a code in Processing that applies a filter to a photo by going over each pixel, extracting the RGB/Grayscale value and modifying the RGB values. The program would take the grayscale value and run it through a few if/else statements to determine how much to modify the RGB values. So far I have this for the code but I'm stumped on how to extract the RGB/Gray values of a pixel
PImage method(PImage image) {
loadPixels();
image.filter(GRAY);
for (int i = 0; i < image.width; i++) {
for (int j = 0; j < image.height; j++) {
//This part here is to store the RGB values
float R;
float G;
float B;
//Convert the RGB to Gray
float coordCol = (0.2989*R) + (0.5870*G) + (0.1140*B);
if (coordCol < 60) {
float rDark = R * 0.9;
float gDark = G * 0.9;
float bDark = B * 0.9;
} else if(60 <= coordCol && coordCol <= 190) {
float bTintBro = B * 0.7;
} else {
float bTintYel = B * 0.9;
}
}
}
return image; // change this to return a new PImage object
}
I've tried many methods, get(), pixel[], filter(GRAY), etc but so far I still can't get the RGB values for a pixel

Answer 1

It's a question many will ask themselves because processing encodes it's colors in a non-intuitive manner. But you're in luck, because they totally know about it being that way! The helpful folks that coded Processing made a couple methods that will get you exactly what you want. Here's the documentation for the one to get the R value, you should be able to track the others from there.
Also, here's a short proof of concept demonstrating how to get the ARGB values from your sketch:
int rr, gg, bb, aa;
PImage bg;
void setup() {
size(600, 400);
// now setting up random colors for a test background
bg = createImage(width, height, RGB);
bg.loadPixels();
for (int i=0; i<width*height; i++) {
bg.pixels[i] = color(random(200), random(200), random(200), random(200));
}
updatePixels();
}
void draw() {
background(bg);
// giving visual feedback
fill(255);
textSize(15);
text("R: " + rr, 10, 20);
text("G: " + gg, 10, 40);
text("B: " + bb, 10, 60);
text("A: " + aa, 10, 80);
}
// THIS IS WHERE THE INFO YOU WANT IS
void mouseClicked() {
loadPixels();
int index = mouseX*mouseY;
rr = (int)red(pixels[index]);
gg = (int)green(pixels[index]);
bb = (int)blue(pixels[index]);
aa = (int)alpha(pixels[index]);
}
I hope it helps. Have fun!