Remember, this is 2012. Phone cameras were terrible, so we all had to slap a bunch of filters over our photos to make them palatable. Some were fine. Most were gaudy.
Apple targeted this in their marketing, calling their built-in effects “professional-quality.” They’re...fine, but they’re also 2012 app filters, so. You know.
Similar to the brushes, they expand out from this Pantone-style fan deck.
Some are color-based, others do some kind of blur or texture-mapping. They did a really nice job adapting photo filters to touch here. Take a look at how you can scrub through the black and white filters and change how the photo gets converted to black and white. This is such a neat interaction.