HOUSTON -- If you're wanting an image-change, Houston, which had an image problem of its own not so long ago, is a good place to come.

The city went bust with the oil industry in the mid-80s, and the world thought of it, one Houstonian said, "as having tumbleweed growing in the streets and the buildings boarded up."

But now, after a painful economic recovery and a big boost from its famous adopted son, George Bush, Houston is decked with flags and flowers and playing host to the economic summit of the world's seven participating nations.

And if Houston -- "hot and proud" -- can come back, why can't some sinner-countries find redemption among its steaming pavements and innumerable used-car lots?

Here is Germany, once the jackbooted scourge of Europe, coming on as sports fan and tree-hugger. The German briefing room still hums with the vibes of its victory in World Cup soccer. And Chancellor Helmut Kohl threw a letter over the wall just prior to his arrival, challenging the other six of The Seven to join Germany in a drive to cut carbon dioxide emissions by 25 percent in the next 15 years.

German reunification may still cause shudders among the older generation, but Kohl, as a friend of clean air, will make no new enemies -- as long as you don't count White House Chief of Staff John H. Sununu, who held a news conference warning against "haste" in cleaning up the environment.

It is a matter of some amusement in the vast Convention Center where the press and spokesmen gather that Germany and her old Axis partner, Japan, have been reunited. They are third-floor neighbors and do the most business of any delegations.

At a first-day news conference, Japanese spokesman Taizo Watanabe showed that they are still in cahoots, this time benignly on the environment: Japan, he said, has made the greatest reduction in carbon dioxide emissions of any industrialized country. Fifty years behind schedule, they appear to be conquering the world -- Germany taking custody of Europe, and Japan's old vision of the "Greater East Asia Co-Prosperity Sphere" coming true.

Germany's plan to give financial aid to the Soviets has its critics, as does Japan's to do the same for China. After a generation of well-earned and enforced diffidence in foreign affairs, Japan is back -- and being accused of grossness and crass commercialism in asking for economic sanctions to be dropped against the perpetrators of Tiananmen Square. The Japanese say that the United States will profit even more from renewed trade. But those who remember the Bataan Death March and similar horrors thought Japan could do better its first time out.

So did Japan. The economic geniuses of Tokyo have begun to turn their talents towards peacemaking. They have quietly, humbly tried to revive that battered child of Asian nations, Cambodia.

For the past year they have been behind the scenes dispatching emissaries and observers through their neighborhood. Japan was deeply hurt several years ago when France convened a parley on Cambodia without inviting them. But last year, Japan was invited to Paris for yet another futile conference, and since then, behind the scenes, it has conferred with the Vietnamese government and the prime minister of Thailand, who urgently encouraged them to take a lead in a regional settlement.

Last spring, Tokyo reached down into a low level of the bureaucracy in the Southeast Asia section of its foreign ministry and sent to Cambodia an observer named M. Kohno. He reported that the Cambodian people seemed "inclined" to accept Hun Sen, the prime minister installed by Vietnam, and that the young leader seemed to be trying to loosen Vietnam's grip on his government. Surprisingly, the State Department invited Kohno to Washington to share his impressions with them. The State Department, it seems, has been floundering more than was thought in its search for a policy that would punish Vietnam but prohibit new atrocities by the Khmer Rouge.

Last month, Tokyo convened a cease-fire conference, which was attended by representatives of Hun Sen and Prince Norodom Sihanouk, but not by the Khmer Rouge. The State Department was not, in the words of one observer, "100 percent for it," and later dismissed the results.

But Japan is doing even more. It is leaning on China to cease its arms supply to the Khmer Rouge. It is, apparently, telling China it would be much easier to grant the loans that China wants if it would help end this pathetic war in Asia. You could hardly ask more of the Japanese. It seems that people can change. Ask Houston.