Research On Visual Invariance And Frequency Effect Based On Dynamic Receptive Fields

The research on cognitive process of human visual system has great significance in machine vision and cognitive science, especially now that the two famous theories in this field, which called respectively the theory of early characteristics analysis and the theory of early global perception, are still totally different. In this thesis research was conducted by focusing on visual receptive fields to study corresponding visual phenomena with the method of dynamic receptive fields model based on Gabor function. The main work and some highlights of this thesis were summarized as follows:1. A dynamic receptive fields model was proposed based on Gabor function, then illustrated the operation mechanism of dynamic receptive fields and simulated different patterns of visual receptive fields using the model. The results of the simulation showed that the dynamic receptive fields model based on Gabor function was a good describer of the transfer function of visual system and was able to simulate different patterns of visual receptive fields including some uncorroborated patterns.2. The experiments on invariance of rotation, scale, translation and illumination proved that the receptive fields could change the parameters of itself to achieve the purpose of invariant recognition and explained the getting mechanism of invariant information from dynamic perspective. A hypothesis which means the visual invariance was obtained in the early stage of visual process, was proposed.3. It was discussed whether the contrast effect of frequency exist under the condition that the contrast effect of gray level existed obviously and designed the image experiment in some of which contrast effect of frequency could be observed obviously. For the conclusion of the experiment result, dynamic receptive fields model was used to explain the contrast effect of frequency,which shows that the practical phenomena were accord with the theory. Furthermore some spatial illusion phenomena could be explained by the same method.4. The dynamic receptive fields model was modified by adding a time parameter to describe the process which the receptive fields declined. Then the establishing process of the receptive fields was considered to be opposite to which it declined. By this conclusion the results of topological perceptual experiments were explained in the effective and efficient way. It is very significant that the results might make a connection between two conflictive theories in the visual cognition field.In a word, research on visual system was a complex issue. The dynamic receptive fields model proposed in this thesis theoretically not only conformed to related characteristics of receptive fields but also could actually explain some related visual phenomena, especially made a good effect on describing receptive fields and simulating human visual characteristics, which would have the possibility to unify the theory of early characteristics analysis and the theory of early global perception in further research.