As one of the users who voted to close your question, here's my take on it. Despite your claims that it was an expert level or a research question, your actual phrasing of the question leaves a lot to be desired. The question did not make an effort to show that it is a research question that would be of interest to signal processing folks.
In the current question, the phenomenon is most likely due to physiochemical reasons and is not quite related to signal processing. While I agree with several of Pearsonartphoto's points, I disagree with the notion that just because some biological/physical/chemical reaction could also be written in signal processing terms, it makes it right to do so. That might be an interesting approach to perhaps get a point across, but should not substitute for an answer. For example, in a comment to his answer, I say that the transient effects could also be due to an increased relaxation time of the chemicals in the photoreceptors (plausible). Now the math behind my simple argument is merely an exponential decay, which also comes up in radioactive decay, the Arrhenius equation, RC circuits among several others. Does that mean it is reasonable to explain how long it takes Uranium to decay to Thorium using RC circuits? I would think not.
This site should be for specific questions (within the scope) with specific answers. Definitely research level questions that make you think are welcome here. However, we must stay clear of questions that merely state a commonly observed phenomenon and bluntly ask for a signal processing explanation. The onus is upon the OP to do the preliminary research and in fact show beyond reasonable doubt that there indeed is some signal processing involved here. Formulate that in the question and then ask for an explanation.
Lastly, it is highly disingenuous on your part to play the victim when you knew very well that this site was perhaps not the best place to ask this question. From the very first line of your question:
(...I apologize if this question is not apt in here..)