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Activity Forums Adobe After Effects Expressions Scale based on luminance

  • Scale based on luminance

    Posted by Collin Robert on June 26, 2018 at 7:14 am

    I am trying to make the girl’s shoes 2x’s normal scale. I tried increasing the Horizontal and Vertical pixels by using the displacement map as seen in my image upload. Can an expression be used to scale pixels based on luminance or Hue?

    Thank you!
    Collin

    Collin Robert replied 8 years, 1 month ago 3 Members · 5 Replies
  • 5 Replies
  • Kalleheikki Kannisto

    June 26, 2018 at 8:02 am

    I don’t see how you could achieve this with a displacement map.

    You need to know

    A) what to scale and

    B) around which point

    For A, you need a mask for each shoe, separately. For B you need to track the “attachment points”, i.e. the anchor point around which each shoe gets enlarged, separately.

    With those two things (or, really four, since it is two shoes) in place you can scale each shoe correctly.

    Kalleheikki Kannisto
    Senior Graphic Designer

  • Collin Robert

    June 26, 2018 at 9:29 am

    You are right the anchor points are essential. Apon thinking about it I will track an anchor point to each sock, (without motion tracker if needed). Using the track, Ill add an adjustment layer to scale both the mask layer, and the footage layer. But I cant use “Scale” property twice in one Adjustment Layer, so Ill try “Bulge”. Or “Scale” with the 2 tracked anchor points on separate adjustment layers?

  • Jacob Roth

    June 26, 2018 at 12:22 pm

    You could add a transform effect. That would give you a second Scale attribute.

  • Kalleheikki Kannisto

    June 26, 2018 at 7:20 pm

    Null objects would come in handy here. Once you’ve tracked a sock, you can apply the tracking to a null object and parent both the copy of the footage for the shoe and the matte layer to it. Same for the other shoe. No need for adjustment layers.

    Kalleheikki Kannisto
    Senior Graphic Designer

  • Collin Robert

    June 26, 2018 at 7:35 pm

    Yes! that will be the fastest way. Thank you.

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