For example when there is a rich person being investigated on Law and Order, they nearly invariably show a large portrait of the person on the wall of their palatial abode. It might well vary from show to show but are there people whose sole jobs are creating these paintings for shows? Are they even usually actual paintings? Seeing as they’re rarely on screen for more than a couple of seconds it could just be they’re photos that are done up in Photoshop to look painting-like.
You can find dozens of artists willing to do a quick painting for a TV show or movie if you pay them. They can be done pretty quickly, too – you only have to get the face looking about right (which you do from photos) and then you can paint the rest in.
It may be even more cost-effective than Photoshop, and it will look like a painting (i.e., the surface won’t be flat). Besides, they’ve been doing this in Hollywood for decades, so they probably stick with what they’ve always done.
Mostly it’s just journeymen who toss off a quick, bad painting a job. But occasionally a real artist gets involved. The 1945 Picture of Dorian Gray is a great film; partly due to the pair of paintings done by the Albright brothers. Ivan did the paintingof the accumulated decay of a life of evil, and his brother Malvin did the more conventional portraitof the young Dorian, pre-curse.
If you want to see something like this in action, and you ever visit NYC, I can tell you were to go. At the 42nd Street station on the 8th ave Line (the A, C, and E trains, Just underneath the Port Authority Bus Terminal). There are some shops only accessable form the subway station. One of these shops is an art studio where a painter sits every day, his back to the big glass window, at an easel with a photograph right next to him. In about 2-3 hours you can watch him make an Oil painting reproductioni of that picture (mostly portraits). It is really funny if you pass throught hte station right as he is starting (a mostly blank canvas, maybe an outline or some backround) and then a few hours later pass by and almost finished painting