# How can I count white pixels of an image?
**URL:** https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787
**Category:** Libraries
**Tags:** homework
**Created:** [April 21, 2023, 6:37pm UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787 "2023-04-21T18:37:17Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@bouu28](https://discourse.processing.org/u/bouu28)
#### Post date: [April 21, 2023, 6:37pm UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787/1 "2023-04-21T18:37:17Z")
Hey! So i have this assignement where i need to create a binary image of what my computer camera catches and when i have more than 100 white pixels it should appear a message saying motion detected. The problem is I don’t know how can i count the amount of white pixels that appear.
Any help would be so very appreciated
```auto
import processing.video.*;
Capture cam;
PImage diference;
PImage frameAnt;
PImage binary;
float threshold = 50;
float pxWhite = 100;
void setup () {
size(640, 240);
cam = new Capture(this, 320, 240);
diference = new PImage(320, 240);
frameAnt = new PImage(320, 240);
binary = new PImage(320, 240);
cam.start();
}
void draw () {
if (cam.available()) {
cam.read();
cam.loadPixels();
diference.loadPixels();
frameAnt.loadPixels();
binary.loadPixels();
for (int i = 0; i < cam.pixels.length; i++) {
float cR = red(cam.pixels[i]);
float cG = green(cam.pixels[i]);
float cB = blue(cam.pixels[i]);
float aR = red(frameAnt.pixels[i]);
float aG = green(frameAnt.pixels[i]);
float aB = blue(frameAnt.pixels[i]);
diference.pixels[i] = color(cR-aR, cG-aG, cB-aB);
float b = brightness(diference.pixels[i]);
if(b > threshold)
binary.pixels[i] = color(255);
else
binary.pixels[i] = color(0);
}
diference.updatePixels();
frameAnt = cam.copy();
binary.updatePixels();
}
image(cam, 0, 0);
image(binary, 320, 0);
}
```
---
### Author:  [@mnse](https://discourse.processing.org/u/mnse)
#### Post date: [April 22, 2023, 4:51am UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787/2 "2023-04-22T04:51:11Z")
Hi @bouu28,
Why not doing it a simple way…
- Assuming you are using the default RGB colormode…
- Create a variable and initialize it with the white color representation `color(255)`
- Loop through the pixels array, like you are doing already above in your code and check if the current pixel value is equal (`==`) to the white variable value from above.
- If equal increment a counter.
- If you only need to check for a certain amount (ie. more than 100) you can check if the counter is above (`>`) that value and set a flag (ie boolean variable) to true and break out of the loop.
- Do actions based on your flag which says more than 100 white pixels or not.
Hope that helps…
Cheers
— mnse
---
### Author:  [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [April 22, 2023, 11:08am UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787/3 "2023-04-22T11:08:36Z")
> [@mnse](#):
>
> If the current pixel value is equal (`==`)
Or you use brightness (…) \> 88 or so; due to antialising some white pixels might not have the exact value 255
---
### Author:  [@mnse](https://discourse.processing.org/u/mnse)
#### Post date: [April 22, 2023, 12:18pm UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787/4 "2023-04-22T12:18:01Z")
Hmmm! I would keep it simple…
If the exercise says count white pixels and not count almost white pixels I wouldn’t mess around with stuff like antialiasing. But if the exercise says to consider a threshold to detect almost white pixels the brightness approach would be a good one …
Cheers
— mnse
---
### Author:  [@bouu28](https://discourse.processing.org/u/bouu28)
#### Post date: [April 22, 2023, 5:20pm UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787/5 "2023-04-22T17:20:06Z")
Hey
So i’ve been trying all that i can remember and what you guys told me too but nothing is working. I’m probably doing something wrong but I don´t see where.
I don’t want to ask too much cause your help is already good for real but if anyone could share some code that might help with this I would me so grateful.
Thank you so much tho for your help.
---
### Author:  [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [April 22, 2023, 6:05pm UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787/6 "2023-04-22T18:05:54Z")
Please post your entire code
---
### Author:  [@jafal](https://discourse.processing.org/u/jafal)
#### Post date: [April 22, 2023, 9:00pm UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787/7 "2023-04-22T21:00:25Z")
Hi
Good reference
[ ](https://www.youtube.com/watch?v=j-ZLDEnhT3Q)
> **[Read all white pixels - Processing Forum](https://forum.processing.org/one/topic/read-all-white-pixels.html)**
>
> Processing Forum
---
### Author:  [@bouu28](https://discourse.processing.org/u/bouu28)
#### Post date: [April 22, 2023, 9:48pm UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787/8 "2023-04-22T21:48:41Z")
Here is the code that i have, this was my last try, i’m gonna try other way now
```auto
import processing.video.*;
Capture cam;
PImage difference;
PImage frameAnt;
PImage binary;
float threshold = 50;
//float pxBranco = 100;
Boolean pxBranco = true;
color white = color(255);
int count = 0;
void setup () {
size(640, 240);
//sqr = new SqrOsc(this);
//sqr.play();
cam = new Capture(this, 320, 240);
difference = new PImage(320, 240);
frameAnt = new PImage(320, 240);
binary = new PImage(320, 240);
cam.start();
}
void draw () {
if (cam.available()) {
cam.read();
cam.loadPixels();
difference.loadPixels();
frameAnt.loadPixels();
binary.loadPixels();
for (int i = 0; i < cam.pixels.length; i++) {
float cR = red(cam.pixels[i]);
float cG = green(cam.pixels[i]);
float cB = blue(cam.pixels[i]);
float aR = red(frameAnt.pixels[i]);
float aG = green(frameAnt.pixels[i]);
float aB = blue(frameAnt.pixels[i]);
difference.pixels[i] = color(cR-aR, cG-aG, cB-aB);
float br = brightness(difference.pixels[i]);
if (br > threshold)
binary.pixels[i] = color(255);
else
binary.pixels[i] = color(0);
}
for (int x = 0; x < binary.width; x++) {
for (int y = 0; y < binary.height; y++) {
int loc = x + y * binary.width;
if (binary.pixels[loc] == color(255)) {
if (loc <= 100) {
fill(250, 0, 0);
square(width/2, height/2, 50);
}
}
}
}
difference.updatePixels();
frameAnt = cam.copy();
binary.updatePixels();
}
image(cam, 0, 0);
image(binary, 320, 0);
}
```
---
### Author:  [@glv](https://discourse.processing.org/u/glv)
#### Post date: [April 23, 2023, 10:08am UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787/9 "2023-04-23T10:08:25Z")
Hello @bouu28,
Try moving this code (from your last post) to the end of _draw()_ to see what it is doing:
```auto
for (int x = 0; x < binary.width; x++) {
for (int y = 0; y < binary.height; y++) {
int loc = x + y * binary.width;
if (binary.pixels[loc] == color(255)) {
if (loc <= 100) {
println(x, y); // glv added to your code
fill(250, 0, 0);
square(width/2, height/2, 50);
}
}
}
}
```
You are displaying an image over the above code in your example!
The above code at the end of _draw()_ displays a red square when there is motion at a _loc \<= 100_ (in this case x\<=100, y = 0).
I added a _println()_ to display x, y to the console; this is a useful tool for examining and debugging code.
Note:
There is no anti-aliasing in the `binary[]` pixels array; it will only contain 0 or 255.
Do not concern yourself with this and stay on track.
Your code is already doing this:
```auto
if (br > threshold)
binary.pixels[i] = color(255);
else
binary.pixels[i] = color(0);
```
Consider adding a variable to also count these.
There are resources (tutorials, references and examples) here to peruse:
> **[Welcome to Processing!](https://processing.org/)**
>
> Processing is a flexible software sketchbook and a language for learning how to code. Since 2001, Processing has promoted software literacy within the visual arts and visual literacy within technology…
References:
- [++ (increment) / Reference / Processing.org](https://processing.org/reference/increment.html)
- [else / Reference / Processing.org](https://processing.org/reference/else.html)
There is an example that generates a histogram of all the brightness levels; try to glean some insight from this.
Try adding a variable to count the occurrences of 0 or 255 in this simple example:
```auto
int data [] = {0, 255, 0, 0, 255, 0, 255, 0, 0, 255};
for (int i=0; i
### Author:  [@bouu28](https://discourse.processing.org/u/bouu28)
#### Post date: [April 23, 2023, 3:46pm UTC](https://discourse.processing.org/t/how-can-i-count-white-pixels-of-an-image/41787/10 "2023-04-23T15:46:03Z")
Hello! So it finally worked 🙂 Thank you so much for your help, I’m really grateful