Answers.Body: <p>Below is how to change the colour of a shape in after effects based on the background colour at a given position:</p>
  <p>Put a null on the position you wish to sample.</p>
  <p>Put this expression in the fill colour of the object you want to change:</p>
  <pre><code>target = thisComp.layer(&quot;BGLAYER&quot;);
  colorpicker = thisComp.layer(&quot;sample 1 null&quot;);
  target.sampleImage(target.fromWorld(colorpicker.position), [0.5,0.5], true, time)
  </code></pre>
  <p>BGLAYER
  is the name of your background layer (eg your video)</p>
  <p>sample 1 null
  Is the null which is colour picking</p>
  <p>You will also need a conditional statement in the expression to switch its opacity on or off - I'm not sure how to do that, but will add it to this answer if I work it out.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-10-09T06:11:47.933Z
Answers.LastActivityDate: 2021-10-09T06:11:47.933Z
Answers.UserDisplayName: tomh
Body: <p>I'm trying to black out/censor segments of a screen-recording. I basically need something to check the color of a pixel on the video, and if the color does not match, it somehow censors the section of the video.</p>
  <p>Example:
  The source video needs to have at position 100;150 the color #f3f3f3. If this condition is true, just display the clip normally, if it's some other color, change the opacity to 0 or apply a blur.</p>
  <p>(preferably in AfterEffects or PremierePro)</p>
  
Tags: <after-effects><premiere>
Title: Change Opacity of Layer based on pixel value of another layer in PremierePro/AfterEffects
UserDisplayName: Mark Fooster
ThreadText: # Change Opacity of Layer based on pixel value of another layer in PremierePro/AfterEffects
  
  (Asked by: username_0 on 2021-10-08)
  
  I'm trying to black out/censor segments of a screen-recording. I basically need something to check the color of a pixel on the video, and if the color does not match, it somehow censors the section of the video.
  
  Example:
  The source video needs to have at position 100;150 the color #f3f3f3. If this condition is true, just display the clip normally, if it's some other color, change the opacity to 0 or apply a blur.
  
  (preferably in AfterEffects or PremierePro)
  
  **Tags:** after-effects, premiere
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2021-10-09. Score: 0 | Accepted answer
  
  Below is how to change the colour of a shape in after effects based on the background colour at a given position:
  
  Put a null on the position you wish to sample.
  
  Put this expression in the fill colour of the object you want to change:
  
  ```
  target = thisComp.layer("BGLAYER");
  colorpicker = thisComp.layer("sample 1 null");
  target.sampleImage(target.fromWorld(colorpicker.position), [0.5,0.5], true, time)
  
  ```
  
  BGLAYER
  is the name of your background layer (eg your video)
  
  sample 1 null
  Is the null which is colour picking
  
  You will also need a conditional statement in the expression to switch its opacity on or off - I'm not sure how to do that, but will add it to this answer if I work it out.
  
  
  ---
  
  