The scientific theory is there, and so are proper glasses. But there is yet another factor to be mastered before best results can be achieved in microscopy: Illumination.
The purpose of pre-processing is to decrease the influence of the environment such as illumination, temperature, noise and the unstable factor of the stream line.
The intrinsic factor influencing the autumn-color leaf is the change of photosynthetic production, and the extrinsic factors are illumination, temperature and moisture.