Google feature requirements are now requesting different image sizes for the same data item.
For example, the Google Structured Data feature for Products shows the following requirement for the product image property.
How to do this in Schema App:
Step 1: Create the images with those different ratios in your website/image storage. This way there is a URL for each of the images.
Step 2: Go to your data item, use the + next to image property to add multiple images.
Step 3: Enter the URL for the different images you created to meet the Google requirement
Step 3. Go to Tools>Image Repair, and setup each image as an image object.
Schema App will pull the sizes of the images from your image online, and since you are linking each image to the data item, it will satisfy the requirement from Google.