Read a book, then see the movie, and comparisons are inevitable. Why didn't the actor more resemble the main character? What happened to the character-A-meets-character-B scene? Why were whole sections left out of the film?

It can be frustrating for the reader expecting to see a beloved book turned into cinematic eye candy only to be disappointed.

Now comes a chance for readers to discuss how movies do or do not live up to the written word and why or why not.

Beginning 7 p.m., the Peters Township Public Library will sponsor the first installment of Books On Screen, a discussion of how four novels and their movie versions stack up.

Each participant receives a book and can check out one of four available DVDs or view the movie at a special library screening. "Mystic River" by Dennis Lehane is first up for discussion. Continuing on Sundays in March, April and May will be "The Quiet American" by Graham Greene, "The Hours" by Michael Cunningham and "High Fidelity" by Nick Hornby.

Books on Screen is part of the Pennsylvania Humanities Council's Read About It program. Started as a pilot program in 2000, Read About It uses libraries to lure readers into discussions in which they might not otherwise engage. Other genres on which discussions are based are: Detecting Women, Facts in Fiction, Life Stories and Pennsylvania Writers.

"Ours is different from other book discussions, because it's not driven by lectures. Rather, leaders are brought in to facilitate discussions. We try to bring in a new audience or those who haven't participated in a book discussion forum before," said Marcie Thurstlic, program communications assistant at the humanities council.

Two other libraries in Western Pennsylvania are participating this time: Penn Area in Harrison City, Westmoreland County, and Indiana, Miss Thurstlic said. Peters was chosen in part because the council is trying to expand the program to regions it has not reached before, she said. There are 16 Read About It programs going on statewide.

David R. Shumway, Carnegie Mellon University English professor, will lead the discussion.

Pier M. Lee, library director, sees the program as another way to reach its 26,905 patrons, calling the book and movie discussion fascinating. She is constantly informally surveying patrons -- in schools and even in the library parking lot -- about their interests.

"As a public librarian, it is important to know what your community needs. I have received specific requests to provide a film theory discussion group. This particular offering from the Pennsylvania Humanities Council seemed to tie in nicely with requests patrons have made to me for library programming."

As of Feb. 15, 30 people had registered for the discussions and six were on a waiting list.

Among the patrons who have signed on are Maura Kelly, 41, a stay-at-home mom, and Kevin Bastos, 33, a Peters Township High School media teacher whose subjects consist of photography, newspaper, advertising, the yearbook and video.

At the library recently, Mrs. Kelly and Mr. Bastos talked about what they hoped to get out of Read About It.

"I enjoy reading, just discussing, talking with people. I really like to argue and the fact that you can sit with a group of people and argue something that's innocuous or no one has any ownership of is to me very interesting," said Mr. Bastos, who belongs to another book club and reads about two books a month.

He thinks it is impossible to compare books and films absolutely because they are different types of media. The written word has the advantages of depth, scope and characterization, he said, but film has the capacity to visualize and an actor can bring something to a role the reader may not have conceptualized.

"Anybody who'd tell me they weren't affected by seeing "Jurassic Park" on the big screen is lying. Don't get me wrong. I loved the book but the movie was fantastic, as well."

For her part, Mrs. Kelly, who reads two or three books a month, regularly attends movies and belongs to a neighborhood book club, said she too, looks forward to the discussions.

When it comes to her reading preferences, she said, "It has to move me deeply. I like to be transported into another person's life for a while and see the world through their eyes even if it's a disturbing topic, and I guess I find that generally the things that move me deeply are disturbing topics. So what other people . . . might consider depressing, I think is very powerful."

During the discussions, she hopes to get a deeper understanding of the link between books and films and of the writing process in general.

"I always like seeing the movie after [reading the book] and it is never as good. That doesn't mean it isn't good. I like seeing the director's interpretation of the book, and it allows you to kind of relive the book a little bit, even though they always leave out parts that you're disappointed that they left out."

In a telephone interview, Mr. Shumway acknowledged the common complaint that movies don't always live up to the books on which they are based. That is due in part to the elements left out when a book is interpreted for the screen, Mr. Shumway said. There also could be problems when characters do not match a reader's preconceived notions.

But books are not invariably better than the film adaptations, Mr. Shumway said, citing "Casablanca," regarded as one of filmdom's best. It is based on an unproduced play by Murray Burnett and Joan Alison called "Everybody Comes to Rick's." He also said director Billy Wilder's 1943 adaptation of "Double Indemnity," by James M. Caine, is considered as one of the great works of cinema.

A movie also may be better for deviating from literature, as in the case of director Howard Hawkes' adaptation of the "Big Sleep," by Raymond Chandler. In that case, Mr. Hawkes created the Lauren Bacall-Humphrey Bogart love story, which makes it the most interesting thing about the film.

The point is books and movies are two different kinds of storytelling, Mr. Shumway said. Of the four books up for discussion, he believes "High Fidelity" made the best adaptation to screen. The movie effectively captures the novel by incorporating the very strong presence of the narrator, he said. Part of its success derives from the fact the movie incorporates a lot of music, bringing it alive in a way the book cannot.

As far as the library program is concerned, Mr. Shumway said, "I hope that [participants] will learn to appreciate both books and films a bit more deeply and understand better how each form works in their different ways."