Basic concepts
This is how it works in a nutshell:
An image property is a reference to an original image from an image provider. By default, an image provider is registered for images uploaded in the CMS.
An adaptive image property may reference different images for different screen sizes.
An image property may have constraints applied to it, such as minimum size and proportions.
These constraints ensure only valid images can be selected by the user, and that they are suitably cropped.
When an image property is rendered, the original image is automatically transformed through scaling and/or cropping.