Passing an array from a template to a helper function

Using Ember, I'm attempting to pass an array from a template

to a helper function

export function segmentArray([array, itemsPerRow]) {

  /* Logic to create and a return multidimensional array */

}

I know images is being populated correctly as I can use the helper on it. However, array is being passed in as "<(subclass of Ember.ArrayProxy):ember355>" with no length or content.

How can I pass in, modify, and return an array?