When your images are displayed in Preview or on the screens at the conference, they will only be as large as the file you insert.
The full display screen is 1920×1080 pixels. Thus, if you want an image to fill the screen, you must insert an image that is 1920×1080.
If your image is only half the size – 960×540 – it will fill only half the screen.
We recommend that your images are at least 600 pixels wide. However, don’t try to make your image any bigger that the original. This will only cause it to be blurry and hard to read. Try to find an original that is larger.
In this case, bigger is indeed better. The larger your image (photograph, table, diagram) the more detail you can show.