Exist several scenarios that occur due large image size.

Steps to reproduce:

1. Go to Administration -> Images, type - Icons
2. Upload large image

Result:
Large image size breaks icons layout. If upload the same image to background type - layout looks fine

Expected:
Layout didn't break

Steps to reproduce:

1. Go to Administration -> Images, type - Icons
2. Upload image with height more than 2000
3. Go to Maps constructor
4. Add element
5. Choose previous uploaded image as icon

Result:
Appears error that "Incorrect value "2048" for "height" field: must be between 1 and 2000". But map successfully saved

Expected:
Can't upload such big image in Administration -> Images or can't save map

Steps to reproduce:

1. Go to Administration -> Images, type - Icons
2. Upload jpg image (image size 427 KB)
3. After upload check image size on frontend

Result:
Image converted to png, but size become bigger (4.2 MB)

Expected:
Correct converting