My application downloads images from the web and encloses them in custom Image objects. Using my Image class I can extract particular data from the images. That data is eventually presented to the user.
With the model-view-controller paradigm in mind, can my Image class be considered a model class or a view class?
It would be considered a model - a view is usually a UI template that a model is mapped to.
In a web-based MVC implementation the view is the HTML template into which the data from the model is populated for display.
You answered it yourself when you said "the data is eventually presented to the user". The model is the programmatic representation that you can modify/manipulate/extract data from. The view is the "presentation". Your image class "eventually" gets presented. That presentation is the view. The image class is the model.
A ViewModel class should only contain properties and view spesific logic such as formatting, deciding which data should be visible and so on