Trying to speak about "logiciel libre"

[MJ Ray]

phil hunt <philh at comuno.freeserve.co.uk> wrote:
> On Thursday 16 May 2002 12:46 am, MJ Ray wrote:
>> ITYM "image conversion" is the noun?
> That phrase is a noun-expression. Both "image" and "conversion" 
> are nouns.

But I think "image conversion" is a noun too, but a sort of compound noun. 
A noun expression can contain adjectives too, I thought.  Is that right, or
do I have to go digging through the linguistics books...?