The field type Image creates a field to add an image to the form.
Tip! If you want to make sure the images in the form is scaled to the screens size, you could add CSS classes for this. Read more about images and CSS classes in the Bootstrap documentation.
Add two Bootstrap CSS classes; img-responsive and col-md-6 in Advanced settings for the Image field. The result is an image that will stay at 6/12 columns in width and at the same time keep proportions and scale accordingly to the screens size.
Example above showing an Image field with two Bootstrap CSS classes, img-responsive and col-md-6.