I introduce a simple analytical approximation for the reflectance from a semi-infinite medium which has scattering and absorption. Its inverse transformation (reflectance to scattering/absorption coefficients) has also simple analytical solution.

See build/transfer.pdf (currently written only in Japanese).

Although this work is original, it is obvious that similar works exist (…​and they are most likely better than mine) since it seems a very basic and common problem. Unfortunately I cannot find them, at least freely avaiable on the Web. Let me know if you find them and I should cite them.