I think you are confusing two different things.
In such words as
blackbird, blueprint, greehouse, redbrick (
BrE),
brownstone (
AmE), etc, where the noun is constructed from an adjective and a noun, the word stress in the noun so constructed is on the first syllable.
When we have an adjective 'describing' a noun, as in
a black bird, a red brick, then the two words are fairly equally stressed. If we wish to contrast the adjective with another adjective, then the adjective will be stressed. Similarly, if we wish to contrast the noun with another noun, then the noun will be stressed.