This has been a bad presidential campaign for columnists, because most of us have been wrong in our estimates and calculations about half of the time.

The campaign has seesawed so unpredictably that it hasn't been difficult to be both right and wrong within the space of a couple of days.George Bush took a beating in some of the early primaries and was prematurely written off. But then he bounced back, sweeping his rivals for the Republican nomination into oblivion.

Then Michael Dukakis, who in the campaign for his party's nomination had been one of the "seven dwarfs," came roaring across the presidential ring, and at the Democratic convention in Atlanta drove Bush onto the ropes. Dukakis left Atlanta with a strong lead in the polls.

But then Bush bounced back, came out swinging at the Republicans' convention in New Orleans, and even with an albatross named Quayle around his neck, has been giving Dukakis a kind of daily lesson in political pugilism.

Particularly fascinating is the transformation the two candidates have undergone.

Bush was earlier battling a public image of indecisiveness, hovering anonymously in the shadow of Ronald Reagan. In a biting column, George Will described him as a lap dog. Some doubted his zeal and commitment to the race for the presidency.

But since the Republican convention, the lap dog has become, if not a Doberman pinscher, at least an assertive German shepherd. The Democratic taunt: "Where was George?" is fading a bit, because now George is everywhere, barking in Boston harbor at the Dukakis environmental record, sniffing out alleged instances of Harvard liberalism, and snarling at Dukakis's prison furlough program.

By contrast, Dukakis was earlier battling a public image of aloof and unamused intellectualism; rather like a very intelligent but highly controlled wire-haired terrier. He seemed reluctant to mix with the crowds, unable to depart from an inflexible game plan. When Bush started darting in on the offensive, Dukakis would bark bravely back.

But in so doing he has seemed to become defensive and even indecisive, beginning to give mixed signals on such issues as defense and the Strategic Defense Initiative. The intelligent terrier has seemed more like a bright, but unfocused poodle.

The improvement in Bush's image is in large part due to the political experience and sophistication of the man who runs his campaign, James Baker.

As a key White House aide through much of the Reagan administration, Baker, along with another former aide, Michael Deaver, was responsible for consolidating Reagan's favorable image on TV. Now Baker is doing it for Bush, choosing the settings, writing the headline they would ideally like to see on that evening's newscasts, and communicating it clearly.

In response, Dukakis has brought back to his campaign John Sasso, who was dropped last year for his overenthusiastic unmasking of plagiarism on the part of Sen. Joseph Biden, a rival Democratic contender for the presidential nomination.

Will image triumph over policy? Dare we hope for a blend of both?