Eisenhower might not have been re-elected president if he had lived in the age of color television.

But in monochrome, like looked upstanding and authoritative because black and white pictures left his features incomplete. We filled them in ourselves and made him everybody's grandpa, a consummate beacon of trust, even if he did have Elmer Fudd's hairline.

He returns in black and white tonight for a 15th anniversary broadcast of the program prepared for the 20th anniversary of D-Day-" CBS Reports: D-Day Plus 20, Eisenhower at Normandy," at 8 o'clock on Channel 9. The original 90-minute film has been edited down into a concise, nostalgic, transporting and colloquial hour.

In his current autobiography "As it Happened," CBS Chairman William S. Paley says he personally talked his old friend Dwight D. Eisenhower into revisiting the sites of the Normandy invasion for CBS News cameras, and Paley says he even tagged along with the crew, and correspondent Walter Cronkite "to tour landmarks of the war with him."

What you get from this report is a sense of the immensity of what Eisenhower told his troops was to be a "great and noble undertaking." Cronkite and Eisenhower first visit Southwick House, near Portsmouth, the English town that became Supreme Headquarters of the Allied Expeditionary Force.

As a carthic rejoinder to the recent ABC fictionalization, "Ike," the program is completely devoid of lurid gossip about alleged love affairs and of the allegedly bitter politicking that went on between Eisenhower and such blowhards as Field Marshal Montgomery. Eisenhower makes no disparaging references to anybody.

He and Cronkite appear to get along like a couple of chummy old dogfaces. "just stop here a minute, Walter," Eisenhower says to Cronkite, who is driving a jeep himself in the countryside beyond the Normandy beaches. What is most stirring about the program is Eisenhower's reverence for the men who fought the battle, not the men who planned it. "The thing that pulled us out," he says, "was the bravery and courage and initiative of the American G.I."

At the end, the two walk among thousand of white crosses at the American cemetery near St. Laurent, overlooking Omaha Beach. "I devoutly hope that we will never again have to see such scenes as theses," Eisenhower says. Of the 9,000 buried there and others who died in the invasion and the war he sayy, "They bought time for us, so that we do better than we want before."

From 1959 to 1967, CBS News carried on the Edward R. Murrow tradition with "CBS REPORTS," A MONTHLY SERIES OF DOCUMENTARIES IN PRIME TIME. THE PROGRAM BECAME A VICTIM OF BITTER POLITICKING ITSELF - THE CBS corporate kind. Murrow left the network in 1961 and Fred W. Friendly, executive producer of "D-Day Plus 20 Years" and president of CBS News, left dejectedly in 1966.

One of the most imposing things about "CBS Reports" was its opening and closing musical signature, the stateliest theme from Aaron Copeland's "Appalachian Spring." There was something grand and goose-pimply about the way it was used; it said, perk up your ears, here comes something great. A CBS News spokesman said yesterday there is talk of bringing the theme back, but "CBS Reports" will never be the same. Three Women

From the opening chorus of "Peek-A-Boo" to the closing one of "Toodle-Oo," Thames Television's "The One and Only Phyllis Dixey" proves an affecting and melancholy biography of a stripteasing trailblazer. The 90-minute program, at 8:30 tonight on Channel 26, is part of an evening devoted to women in varying stages of distress and, in Dixey's case, varying stages of undress as well.

According to this loving though eventually morbid period reproduction by writer Philip Purser and director Michael Tuchner, Dixey was hardly a salacious bumper and grinder but instead appeared in quaint little pageants of even religious tableaus, the common thread of them being that they required her to remove most of her clothing. The film reminds us, in an age of libidinous exhibitionism, how tantalizing the tease can be, and actress Lesley-Anne Down, in the lead role, is an entirely healthful pleasure to observe.

Down's performance is particularly impressive for the way she ages the character through the decades, at one moment the toast of England with her tasteful revues and then, following World War II, largely forgotten by a public demanding more explicit and less polite displays of sex in public. The art of suggestion dropped dead. Dixey herself, having been reduced to the position of a domestic servant, does her own final, sad toodle-oo from a lonely hospital bed.

From this immersion in innocence of the past we plunge into the all-hung-outness of the present with "Hard Work," a half-hour documentary at 10:30 on Channel 26. Local filmmaker Ginny Durrin shot the film at a 1978 convention of American prostitutes in Washington and concentrated on the group's articulate and spirited leader, Margo St. James, who runs 5 miles every morning, falls in love "every year at least once," likes "a nice strong arm" around her, and thinks the national de-criminalization of prostitution would end a lot of needless legal harassment and, symbolically anyway, shameless male hypocrisy.

Durrin may have paid too much attention to the journalists and TV newsfolk who followed St. James all over town - St. James refers at one point to "the press and other groupies," which suggests her view of the omnipresent entourage. But this is still a lively, forthright, perceptive and attentive film, and it has a lot to say about things one might think have already been said too much about - role playing, game playing and the number of standards people employ for judging the conduct of others.

The idea of prostitution as merely an alternative "life style" may be pushing open-mindedness a trifle far, but it still comes off as preferable to the screaming extremism of a fundamentalist preacher to whom "prostitution" is somehow synonymous with "communism."

St. James' life up to now is touchingly and economically evoked with a montage of home snapshots, which she narrates. She speaks with passion but hardly without an ironic humor in her own behalf, and she looks like fun.

The first of the three programs about women, "Marilyn," will be shown at 8. This black and white film, a quickie on Marilyn Monroe's life produced soon after her death, has some valuable footage, but retroactive innocence is hard to come by; we know much more about Monroe's life now than was known to these film-makers, and narrator Mike Wallace, in 1962.

It's an old coincidence that programs about President Eisenhower and Marilyn Monroe, two disparate but unmistakable '50s icons, are being shown at the same hour on two different stations, but the program that will beat them both in the ratings - an a return itself - is yet another episode of "Happy Days" on ABC. Given a choice, people will take a '50s that never were to a '50s that really happened. The decade has become a mere commercial commodity, as readily marketable as peeks at Phyllis Dixey's flesh or the time-release companionship of a Margo St. James. CAPTION: Picture, Walter Cronkite, and Dwight Eisenhower in "D-Day Plus 20 Years"