Here are some options, depending on the context:
Formal:
* Collection: This is a general term for any group of pictures.
* Gallery: Used for a collection of pictures displayed in a specific space.
* Portfolio: Used for a collection of pictures shown to represent an artist's work.
Informal:
* Set: For a group of pictures that go together, like a series.
* Pile: For a random collection of pictures.
* Album: For a collection of pictures bound together.
Creative:
* Panorama: For a collection of pictures that show a wide view.
* Mosaic: For a collection of pictures that are put together to form a larger image.
* Display: For a collection of pictures arranged for viewing.
The best option depends on what type of pictures you're referring to and the tone of your writing.