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RGB Math Components

For you math whizzes out there, Filter Forge 2.0 introduces 24 new RGB Math components that operate on RGB color channels and include arithmetic, trigonometry, power, roots and logarithms, rounding, conditional operations, linear interpolation and directional derivatives. Thanks to the support of unlimited HDR colors, these new components can handle unlimited double-precision floating-point numbers, from tiny fractions to trillions, both positive and negative. To help you fine-tune and debug the calculations, we're also introducing the new Color Inspector which lets you see the exact RGB color values of any component's output.

RGB Math Components

List of RGB Math Components


  • Add
  • Subtract
  • Multiply
  • Divide
  • Abs
  • Negate

Power, Root and Logarithm:

  • Power
  • Root
  • Log


  • Sine
  • Cosine
  • Tangent
  • ArcSine
  • ArcCosine
  • ArcTangent
  • ArcTangent 2


  • Ceil
  • Floor
  • Round

Conditional Operations:

  • Min
  • Max
  • If

Other Components:

  • Lerp (means "linear interpolation")
  • Derivative (or "slope")

Derivative Explained

This scary-sounding but powerful component deserves additional explanation. Mathematically, it calculates a channel-wise directional derivative of a surface specified by its Source input along a direction specified by its Angle input. To put this in simpler words, this component treats its input image as a height map (actually, three height maps – one for each RGB channel) and calculates the surface slope for a specified "viewing angle" – the steeper the slope, the brighter the output:

Derivative Explained

Note that the output values of the Derivative component can be negative:

Negative Derivative

Despite its mathematical roots, this component has many uses for a digital artist. For example, it can be used for detecting edges, simulating snow or dust-covered surfaces, assembling custom normal maps, or creating novel lighting effects that are impossible to achieve using the "fixed-function" lighting system built into Filter Forge.

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(after showing Filter Forge to a class at Adobe MAX 2009)

Russell Brown
Senior Creative Director
Adobe Inc.

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“It's a powerful and logical way of creating effects that's relatively easy to learn by seeing how other effects are built. Creating filters from scratch is time-consuming, but for a wider user group, it's a great way to modify already-created effects.”

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Digital Arts

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