We released a preprint on XCR, a fast, structure-preserving Retinex method based on a complex exponential kernel, on Jxiv, the preprint server of the Japan Science and Technology Agency.

XCR processes 1080p video at an average of 15.32 FPS on a CPU alone (measured on a Snapdragon X PC), without a GPU, demonstrating the potential of real-time low-light enhancement. Its ideas were later reorganized under a single principle, the sigmoid derivative, and evolved into our successor method, SD-Retinex.