Page with dotty portraits lacking an introduction to Roy Lichtenstein? (3,6)

I believe the answer is:

pop artist

I'm a little stuck... Click here to teach me more about this clue!

'portraits lacking an introduction to roy lichtenstein?' is the definition.
I can't judge whether this definition defines the answer.

'page with dotty' is the wordplay.
'page' becomes 'p'.
'with dotty' becomes 'opartist' (I can't justify this - if you can you should believe this answer much more).
'p'+'opartist'='POP ARTIST'

Can you help me to learn more?

(Another definition for pop artist that I've seen is " Musician".)

I've seen this clue in The Guardian.

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