Extracting unique values from array

I performed MorphologicalComponents on an image, and from there used SelectComponents to filter out my desired components. Is there a way to extract out the unique values from the entire array? i.e. get a list of the labelled component values

I tried using DeleteDuplicates, but that only works on a list, and also tried using Select with a search criteria #>0, but that didn’t work out as well.

Thank you!