PlanckianJitter

Simulate color temperature variation via Planckian locus jitter. mode and magnitude control the shift. Good for robustness to different light sources.

This transform adjusts the color of an image to mimic the effect of different color temperatures of light sources, based on Planck's law of black body radiation. It can simulate the appearance of an image under various lighting conditions, from warm (reddish) to cool (bluish) color casts.

PlanckianJitter vs. ColorJitter: PlanckianJitter is fundamentally different from ColorJitter in its approach and use cases:

1. Physics-based: PlanckianJitter is grounded in the physics of light, simulating real-world color temperature changes. ColorJitter applies arbitrary color adjustments.
2. Natural effects: This transform produces color shifts that correspond to natural lighting variations, making it ideal for outdoor scene simulation or color constancy problems.
3. Single parameter: Color changes are controlled by a single, physically meaningful parameter (color temperature), unlike ColorJitter's multiple abstract parameters.
4. Correlated changes: Color shifts are correlated across channels in a way that mimics natural light, whereas ColorJitter can make independent channel adjustments.

When to use PlanckianJitter:

• Simulating different times of day or lighting conditions in outdoor scenes
• Augmenting data for computer vision tasks that need to be robust to natural lighting changes
• Preparing synthetic data to better match real-world lighting variations
• Color constancy research or applications
• When you need physically plausible color variations rather than arbitrary color changes

The logic behind PlanckianJitter: As the color temperature increases:

1. Lower temperatures (around 3000K) produce warm, reddish tones, simulating sunset or incandescent lighting.
2. Mid-range temperatures (around 5500K) correspond to daylight.
3. Higher temperatures (above 7000K) result in cool, bluish tones, similar to overcast sky or shade. This progression mimics the natural variation of sunlight throughout the day and in different weather conditions.

• The transform preserves the overall brightness of the image while shifting its color.
• The "blackbody" mode provides a wider range of color shifts, especially in the lower (warmer) temperatures.
• The "cied" mode is based on standard illuminants and may provide more realistic daylight variations.
• The Gaussian sampling method tends to produce more subtle variations, as it's centered around daylight.
• Unlike ColorJitter, this transform ensures that color changes are physically plausible and correlated across channels, maintaining the natural appearance of the scene under different lighting conditions.