07.11.2023 – Colour match and Tracking

Week 6 – Color Match and 2D/2.5D Tracking in Nuke

Color Match

In Nuke, achieving accurate color matching involves the use of specific knobs in “Grade” node:

• Whitepoint: Pick the original color to match the white balance.
• Gain: Select the color you want to match.

To match colors from A to B, a technique involves blurring each image, dividing, and then multiplying the divided image with the original image.

When working with multiple nodes together, you can create a clone through ‘Edit-Clone’, and a small ‘C’ will appear in the corner of the cloned node.

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Tracking

The Transform node in Nuke is a versatile tool for handling translation, rotation, scale, tracking, warping, and motion blur. It can be used in a combined or separate manner for various operations.

There are three types of tracking:

• 2D Track: Involves tracking in X and Y directions, suitable for screen replacement, parallax tracking, and shots without perspective or spatial movement.
• 2.5D Track: Uses 4 points and mimics perspective (not real), beneficial for tracking when a 2D track has perspective.
• 3D Track: Involves tracking in X, Y, and Z directions, used for 3D matchmove.

For tracking a shot:

1. Create a tracker node and connect it to the shot.
2. Add a tracker point and position it in the area to be tracked. (An enlarged view for the tracker point is available.)
3. Set the current frame as the reference frame in the “Transform” tab and calculate the data.

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Applying Tracker Data to Other Nodes:

• Change Knob: In the Transform tab, select “match-move-1-pt” (1pt for a single point, or “match-move” for multiple points) and connect the tracker node to the node you want to matchmove.

• Export Data into Transform Data (Recommended): This is connected with the original tracker node using Expression. When you retrack the data, it is automatically applied to the connected node. Export data below the tracker data.

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4 Points Track for Screen:

1. Create 4 trackers and position them clockwise.
2. Calculate the input.
3. Check all T/R/S knobs.
4. Set the current frame.
5. Export using “CornerPin2D (use current frame)” and connect it. (Check the cornerpin data using Merge (difference) or Laplacian node.)

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PlanarTracker:

Utilize the “PlanarTracker” node to track using roto. Similar to the “Roto” node, creating it generates a “PlanarTrackLayer” into the Root. Roto and track the desired area, match the plan to the perspective, and export tracking data in the “Tracking” tab with “CornerPin2D”.

Pre-Tracking Treatment:

Before tracking, it’s advisable to adjust the original plate for better results. This may involve denoising the plate using Denoise and Median nodes, increasing contrast with a Grade node, and, in certain cases, utilizing a Laplacian node for improved tracking.