The major studios are not experiencing a box office slump. Thanks to a potent first quarter that has offset a weak summer, the majors have taken in $4.333 billion at the domestic box office. Through the same point in 2004, their box office receipts had amounted to $4.301 billion. This weekend, total box office of $148.9 million — led by the surprising $56.1 million bow for 20th Century Fox’s “Fantastic Four” — was higher than last year’s figure, if only by the slimmest of margins. The weekend-to-weekend comparison has never been the best measure of box office strength (during the so-called “slump” there have actually been several weeks, for instance, where 2005 has outpaced 2004), but the streak has been the basis for many cavalier pronouncements that Americans were no longer interested in going to the movie theater. So, why is total box office down for the year? Look at the indies. Last year, because of the runaway success of “The Passion of the Christ” and “Fahrenheit 9/11,” independent distribs took in $633 million through the second weekend of July. This year, without a blockbuster to match those titles, the sector has grossed $189 million, a difference of more than $440 million. That shortfall is the sole explanation for why this year’s box office is trailing 2004 by 8.4% or $4.522 billion to $4.934 billion.