Exposure Fusion

Implement exposure fusion to blend multiple exposures without HDR tonemapping, leveraging quality metrics to produce a seamless image. This technique is crucial in HDR Imaging as it allows for the combination of differently exposed images, capturing a wider dynamic range.

Exposure fusion directly blends images using weight maps based on contrast, saturation, and well-exposedness, which are calculated as $C = |\nabla I|$, $S = \text{std}(R, G, B)$, and $E = \exp(-\frac{(I - 0.5)^2}{2\sigma^2})$.

1. Calculate contrast using the Laplacian filter.
2. Compute saturation as the standard deviation across color channels.
3. Determine well-exposedness using a Gaussian function centered at 0.5.

This technique is widely used in digital photography to capture high-contrast scenes.