choosing image style during content creation I am seeking for a method to enable users to:


choose image style (thumbnail, medium, large, ...) during content creation 
change this style anytime during content update


Right now, with "Image" module on, the image field style can be decided only during content type creation.

I tried to use "Media" module 7.2, and there is possibility to choose image style during content creation, but no possibility to change it later.
The Formatter Field module looks like the right one. Here is a quote about it (from the module's project page):

... provides a mechanism for specifying a formatter and formatter settings to be used for displaying a field, on a per-entity basis. By default, Drupal provides formatters and settings per entity bundle, but in certain situations it is necessary to choose the formatter at the entity level.
For example, say you have a page node with an image field. Normally, you would select an image style as the formatter, and all page nodes would use that same image style. With this module, you can add a formatter field to page nodes, which is hooked up to the image field. Then when the node is created or edited, the image style can be selected per-node.