value of currentPage will change whenever a filter from sidebar is chosen. Hence the view will replace the current page according to that.
if we push then that will add a new column for the view which should be the case when we want to show the imageviewer. Right?

not necessarly, as an extra step of optimization, i would keep the first page always the same (and change the model to it)
while for the other pages, a normal push/pop would be done as is a bit less frequent

But each model ( ImageFolderModel, ImageTimeModel, ImageLocationModel) would require a different delegate.
So isn't there need of different Pages (for UI) for each model?