get the operating system of an Amazon image via Fog

get the operating system of an Amazon image via Fog

My end goal is to get the operating system of an Amazon image. When I do:
connection = Fog::Compute.new(provider: 'AWS',
aws_access_key_id: 'blah',
aws_secret_access_key: 'thing')
images = connection.describe_images('Owner' => 'self').body['imagesSet']
The data I get returned does not include platform, as this documentation
suggests. However, I do get values like:
architecture: "x86_64",
imageType: "machine",
kernelId: "aki-825ea7eb",
And if I Google for that kernel ID I find this page saying it's Linux. Is
there a way I can pass kernelId to Amazon via Fog and get back data about
that kernelId, such as linux?
On a separate note, sometimes my images don't have kernelId, so are there
any other fields in a <DescribeImagesResponse
xmlns="http://ec2.amazonaws.com/doc/2012-12-01/"> that are definite
indicators of operating system?