Yusuf's Thoughts

Chromatic Aberration Feedback

3 min read

Inspired by: Okamirufu Vizualizer

The signature post-processing technique used by Okamirufu Vizualizer to give generative visuals a “rendered,” high-end feel. It uses time-delayed RGB splitting to create movement-based color separation.

Operator Families in this Recipe

  • TOPs (Texture Operators): Time-based caching and feedback loops.

Part 1: Movement-Based RGB Split

Instead of a static lens effect, this technique separates colors based on time, making fast-moving objects “ghost” in different colors.

  1. Cache TOP: Take your final Render TOP and connect it to a Cache TOP.
    • Cache Size → 20.
  2. Select TOPs: Create three Select TOPs pointing to your Cache TOP.
    • Select 1: Set Cache Index to 0 (current frame).
    • Select 2: Set Cache Index to -5.
    • Select 3: Set Cache Index to -10.
  3. Reorder TOP: Connect all three Select TOPs to a Reorder TOP.
    • Output Red → Input 1 (Red).
    • Output Green → Input 2 (Green).
    • Output Blue → Input 3 (Blue).
  4. The Result: You now have an RGB split that only appears when objects move.

Part 2: Growth Feedback Loop

To make the visuals “bloom” and grow over time:

  1. Feedback TOP: Connect your Reorder TOP to a Feedback TOP.
  2. Transform TOP: Add a Transform TOP after the feedback.
    • Scale → 1.005.
    • Rotate → 0.1.
  3. Level TOP: Add a Level TOP after the transform.
    • Opacity → 0.98.
  4. Blur TOP: Add a Blur TOP after the level.
    • Filter Size → 2 (Small).
  5. Composite TOP: Connect your Reorder TOP and the Blur TOP to a Composite TOP.
    • Operation → Screen or Add.
  6. Close the Loop: Drag the Composite TOP back onto the Feedback TOP.

Part 3: Final Polishing

  1. Luma Blur TOP: Connect your composite to a Luma Blur TOP for a final soft glow.
  2. HSV Adjust TOP: Use this to boost Saturation and slightly shift the Hue for a more psychedelic feel.

Troubleshooting

  • “It’s getting too bright!” — Lower the Opacity on your Level TOP or the Brightness of the feedback.
  • “The trails aren’t moving.” — Make sure the Transform TOP has a non-zero Scale or Rotate.

Parameter Tuning & Behavior

ParameterBehavior
Cache IndexHigher negative values = more pronounced time-based color separation (ghosting).
Feedback ScaleHigher = trails expand faster; Lower = tighter, more concentrated trails.
Feedback RotationHigher = more spiral-like motion in trails; Zero = straight expansion.
Level OpacityHigher = trails persist longer (more “ghosting”); Lower = trails fade out quickly.
Blur Filter SizeHigher = softer, glowier feedback; Lower = sharper, more defined trail edges.

Network Architecture

To visualize how the data flows, here is a map of the final network:

[ INPUT ]
Render TOP
    │
    ▼
[ Cache TOP ] (Size 20)
    │
    ├─▶ [ Select TOP ] (Index 0) ──┐
    ├─▶ [ Select TOP ] (Index -5) ─┼─▶ [ Reorder TOP ] (R, G, B Split)
    └─▶ [ Select TOP ] (Index -10) ┘           │
                                              ▼
[ TOP FEEDBACK LOOP ] ◀───────────────────────┘
    │
    ▼
[ Feedback TOP ] ──▶ [ Transform TOP ] ──▶ [ Level TOP ] ──▶ [ Composite TOP ]

Data Flow Explanation

  1. Caching: The Cache TOP stores a short “history” of the last 20 frames.
  2. Splitting: The Select TOPs grab frames from different moments in time (current, 5 frames ago, 10 frames ago).
  3. Colorizing: The Reorder TOP puts these different moments back together, but assigns them to the Red, Green, and Blue channels. This creates the “time-based” RGB split.
  4. Feedback: The Transform TOP inside the loop scales the image slightly up, which makes the “trails” expand outward in every frame, creating a blooming effect.

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