Homomorphic Filter Function Using Frequency Domain Processing Methods

This article presents a homomorphic filter function based on frequency domain processing methodology. The homomorphic filter function operates in the frequency domain and is designed to handle non-Gaussian filtering scenarios including Butterworth and exponential filter types. Implementation typically involves logarithmic transformation of the input image, followed by Fourier transform application for frequency domain manipulation. The core algorithm applies customized filter functions (with adjustable cutoff frequencies and order parameters for Butterworth implementation) to separate illumination and reflectance components. Through inverse Fourier transform and exponential operations, the filter significantly enhances image quality by simultaneously normalizing brightness and improving contrast. This technique demonstrates particularly notable performance improvements when processing darker images where dynamic range compression and detail enhancement are critically required.