I have a file of pictures I use while I'm writing. They are pictures of buildings, trees, views, flowers, etc. I have many, many pictures of rooms. Strangely, I don't have any pictures of people.
When I first started writing seriously five or so years ago I would always find pictures of people I would use as jumping-off points for my characters. I know of many authors that swear by this technique, but I don't do it any more. I find it too limiting.
I need to look at pictures of rooms for details. What does the ceiling look like? How is the furniture situated? What kind of fabric is used? Remember; I write stories happening 70 years ago in a country I don't live in. The internet and picture books are my telescope to the past. I can look at old menus; read books written in the period, look at pictures of old automobiles. I look at lists of what music was popular, what plays were being performed, etc. But faces? No, no, no!
I do have pictures of people, but for the clothes. How narrow are the belts? How big are the hats? What style are the shoes? What colours are the most prevalent? Actually, I have a fairly comprehensive knowledge about clothes (I was a costume designer at one point), so most of these pictures are for confirmation that my knowledge is correct.
I don't want faces. I have the faces in my head and I want readers (if I ever have any) to make up their own pictures. I'll say if someone's got curly hair if it's a character note (for the character or for someone else). I'll mention someone being exceptionally tall or short. I'll talk about the wart which she tries to hide. Someone could talk about someone's blue eyes or extremely long eye lashes. Physical similarities are also mentioned. But I'm not copying anyone's face. These characters aren't based on anyone and I don't want anyone's face on them; even if it's only in my head.
How important are pictures to you when you're writing? Do you refer to them constantly? Do you have pictures of your characters?