focus warning

[jameswilson]

Im thinking aloud here as im not sure if my idea is workable. I was reading an article on autofocus systems the other day (i always wondered how it worked) and it appears its all based on the histogram. As cameras can monitor this histogram and look for focus issues and adjust on the fly, could zm have (another) component that could be disabled that could check for focus issues say once an hour etc. This way if we do get any focus drift we could set an alarm, or email alert. Again just wondering and if its a load of work forget it

[zoneminder]

Monitoring the histogram per se isn't very hard. However I think auto-focus works by moving focus back and form and then finding the minimum point. I don't think there is any deterministric method for saying one particular shape of histogram implies focus or otherwise. Rather it just uses a comparion as the focus is moved. I could be wrong though, so if you have an algorithm to hand just point me at it and I will take a look.