To find out uniq values from an array of hashes based on an input hash

a = [
  { :color => "blue", :name => "wind" },
  { :color => "red", :name => "fire" },
  { :color => "white", :name => "wind" },
  { :color => "yellow", :name => "wind" },
  { :color => "green", :name => nil },
  { :color => "white", :name => "snow" }
]

I have another hash
b = { blue: 'blue', white: 'white', red: 'red', green: 'green' }

The result I need is:

['wind', 'fire']

# To find out uniq names based on the input hash.

What I tried:

names = a.map{ |i| {i[:color], i[:name]} }.delete_if { |key, value| value.nil? }
resultant_names = []
b_values = b.values

b_values.each do |c|
  if names[c]
    resultant_names << names[c]
  end
end
resultant_names.uniq

Need a better approach please. This goes with too many loops.