The mismatch of the code and the equation (9) in the paper

[blindwang]

Thank you for your excellent work! I noticed a small issue in the code that might be causing a mismatch with Equation (9) in the paper. Specifically, the formula for expanding dark features in the paper includes a negative sign, but the current implementation uses a positive sign for both dark and bright features.

Here’s a more detailed description of the issue:

1. Code Implementation: The current code computes the exponential function as:

   y = np.exp(par * (image - mu_image))

And the par is in [0.5, 1, 2, 5].
2. Equation (9) in the Paper: According to the paper, the formula for expanding dark features should include a negative sign:
$$\tilde{I}_2(x, y, t) = \exp\left[-\delta_2 \cdot (I(x, y, t) - I^l(x, y, t))\right]$$