Abstract: We present an implementation of weight selection in multi-scale retinex (MSR) using the biogeography-based optimization algorithm (BBO). The existing MSR algorithm provides the same values to the Gaussian filters with different scales and cannot ensure the best enhancement results in various environments. We use BBO for weight selection to optimize the enhancement in MSR. The optimization of weight selection compensates for the defects of the scale parameters in Gaussian filters. Extensive simulations with comparisons to the existing MSR verify that our method achieves better enhancement results.