I dont think men look at images more than women. Women look at other women, and images of women more than men do. They also look at them differently than men do. While its true that theres a ridiculous amount of male targeted porn/semi-porn out there, your average male has no need to, and doesnt, spend alot of time looking at the images in order to uh, conclude his business. Women on the other hand will spend more time on each image of a woman(fashion, fitness related), and spend more time overall in their day looking at and evaluating other women.
I also think the male brain receives a female image as a collection of sexual objects (breasts, legs, butts, etc). I think the female brain processes the image more as a whole, and not so much as an assortment of body parts of varying degrees of interest.