The Gerchberg-Saxton algorithm is a computational method used in optics and image processing. It aims to reconstruct a complex image from its intensity measurements, typically in the context of Fourier optics. The algorithm iteratively refines an initial guess of the image by alternating between the spatial and frequency domains. This technique is particularly useful in applications like holography and phase retrieval, where only the intensity of light is measured, not its phase. By applying constraints in both domains, the Gerchberg-Saxton algorithm converges towards a solution that approximates the original image, making it valuable in various scientific fields.