# The algorithm is too slow

**URL:** https://discourse.processing.org/t/the-algorithm-is-too-slow/16553
**Category:** Coding Questions
**Created:** [December 21, 2019, 5:27pm UTC](https://discourse.processing.org/t/the-algorithm-is-too-slow/16553 "2019-12-21T17:27:32Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![costachemadalin](https://avatars.discourse-cdn.com/v4/letter/c/58956e/32.png) [@costachemadalin](https://discourse.processing.org/u/costachemadalin)
#### Post date: [December 21, 2019, 5:27pm UTC](https://discourse.processing.org/t/the-algorithm-is-too-slow/16553/1 "2019-12-21T17:27:32Z")

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Hello, i am trying to calculate disparity from 2 rectified images and for that i need to take every pixel from left image and seach in one line from right image and find the similar pixel ,the dimension of the images is 640x480 .

I need to run disparityImage(PImage imgL, PImage imgR) in draw() and is too slow ,the function is execute in 1-2 seconds ,but if i comment these lines of code “minD=d;rightX=xr;” from the if block  
the function is execute in 3-5 miliseconds. I don’t understand which is the problem with my code,i tried too many hours to find out but i couldn’t.

```auto
void disparityImage(PImage imgL, PImage imgR) { 
    for (int x=0; x<imgL.width; x=x+1) {
      for (int y=0; y<imgL.height; y=y+1) {    
        color imgleft=imgL.get(x,y);
        float r1=red(imgleft);
        float g1=green(imgleft);
        float b1=blue(imgleft);

        float minD=Integer.MAX_VALUE;
        int rightX=0;

        for (int xr=0; xr<imgR.width; xr++) {    
          color imgright=imgR.get(x,y);
          float r2=red(imgright);
          float g2=green(imgright);
          float b2=blue(imgright);
          
          float d=dist(r1, g1, b1, r2, g2, b2);

          if (d<minD) {
            minD=d;
            rightX=xr;
          }
        }
      }
    }
  }

```

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<div class="post-metadata">

### Author: ![Chrisir](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/chrisir/32/45_2.png) [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [December 21, 2019, 6:03pm UTC](https://discourse.processing.org/t/the-algorithm-is-too-slow/16553/2 "2019-12-21T18:03:23Z")

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It seems get is slower than pixels[]

[https://processing.org/reference/pixels.html](https://processing.org/reference/pixels.html)

Also dist is slow and there are faster ways like pythagoras but without the squarerroot (doesn‘t matter since you only need the relative distance)

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### Author: ![jeremydouglass](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/jeremydouglass/32/20_2.png) [@jeremydouglass](https://discourse.processing.org/u/jeremydouglass)
#### Post date: [January 10, 2020, 11:18pm UTC](https://discourse.processing.org/t/the-algorithm-is-too-slow/16553/3 "2020-01-10T23:18:21Z")

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`get()` is much slower than `pixels[]` – AND `red()` `green()` `blue()` is much slower than bit-shifting.

Explanations for how to optimize your code performance by bypassing these calls are in the reference pages for each function.

[https://processing.org/reference/get\_.html](https://processing.org/reference/get_.html)  
[https://processing.org/reference/red\_.html](https://processing.org/reference/red_.html)  
[https://processing.org/reference/green\_.html](https://processing.org/reference/green_.html)  
[https://processing.org/reference/blue\_.html](https://processing.org/reference/blue_.html)