• Adobe After Effects Expressions

  Logo black or white depending on background brightness

  Posted by Mårten Gunge on April 19, 2016 at 1:54 pm

  Hi.

  I want an expression to make a logo become black or white depending on the background brightness (dark=white logo, bright=black logo).

  I guess that one could use “sample image” in some sort of a way. Please enlighten me.

  Mårten Gunge replied 10 years, 4 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  April 19, 2016 at 9:12 pm

  One way would be to have a light logo with an opacity expression like this:

  bg = thisComp.layer(“background”);
  rgb = bg.sampleImage([bg.width,bg.height]/2,[bg.width,bg.height]/2);
  hsl = rgbToHsl(rgb);
  if (hsl[2] > .5) 0 else 100

  and an expression like this on the dark logo:

  bg = thisComp.layer(“background”);
  rgb = bg.sampleImage([bg.width,bg.height]/2,[bg.width,bg.height]/2);
  hsl = rgbToHsl(rgb);
  if (hsl[2] > .5) 100 else 0

  Or you could use a similar concept to control the fill color of a single logo like this:

  bg = thisComp.layer(“background”);
  rgb = bg.sampleImage([bg.width,bg.height]/2,[bg.width,bg.height]/2);
  hsl = rgbToHsl(rgb);
  if (hsl[2] > .5) [0,0,0,1] else [1,1,1,1]

  Dan
• 

  Mårten Gunge

  April 20, 2016 at 9:50 am

  That did the trick. Thanks a lot.

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