As Ray says on my other question:
BOTH pictures present him with fake hair. Initially, the producers didn't want a bald captain, so they issued Patrick Stewart a toupee. I don't know when, why and how this idea changed.
But I can't find anything to substantiate it.
On this question Marian says:
Gene was so right. Plus...I've seen or read (not sure which) an interview with Stewart in which he explains that wigs were tried on him, but he simply looked like a bald guy in a wig, so they let him be natural.
But no one has a reference.
Memory Alpha only says that he wore it for a flashback.
The only other reference I found about it is here but nothing conclusive.
Did he wear a toupee for his audition?