SEOUL -- South Koreans saw an unexpected face one morning late last month in their copies of Hankook Ilbo, a major national newspaper. There on the front page was a photo of dissident politician Kim Dae Jung, beaming as he met reporters for the first time after 2 1/2 months of house arrest.

Kim is an important political figure here, but for years the government has forbidden newspapers to use his picture. The ban is but one of a maze of formal and informal restrictions imposed by the government on the South Korean press.

Editors have long danced along the edges of these limitations, sometimes publishing pictures of Kim conducting political business with his back to the camera.

Now he has reappeared full-face, part of a cautious flowering in the press that began during the three weeks of street demonstrations against the government of President Chun Doo Hwan.

Chun announced last week that he had accepted a package of democratic reforms, including the easing of government restrictions on the press. The speech helped defuse sometimes violent protests that gripped South Korea last month.

Longtime readers say journalists are paying increased attention to sensitive political subjects and are reporting on the feelings of dissidents in unusual detail and length.

Despite objections from the government, South Korean newspapers recently went ahead with prominent stories reporting that other cities would seek to host the 1988 Summer Olympics if Seoul, the scheduled host city, proved unable to hold them.

Recent editions of the Dong-a Ilbo newspaper published an interview with Kim on its front page. All four national newspapers published his photo.

New aggressiveness by the newspapers and looser regulation by the government seem to have given rise to the changes.

Press freedom has been much in the public mind recently, beginning with the trial last December of three men who published confidential government "guidelines" that were dispatched daily to newspaper editors by the Ministry of Culture and Information.

The government never denied the authenticity of what was published. But it said national security had been endangered because some of the guidelines touched on military subjects.

Dissidents here depict the guidelines as orders. Editors often question that view, saying the guidelines in many cases are defied.

The three men were tried in a courtroom packed with cheering supporters. Early last month they got off with probation. The opposition hailed the judge's ruling, saying he had resisted government pressure to impose stern sentences.

Before the verdict, reporters and editors at Seoul Shinmun, a newspaper regarded as a government organ, revolted against their management after the paper reported that the U.S. government had acquiesced in a highly unpopular decision by President Chun to suspend a debate on constitutional reform.

The U.S. Embassy, in a highly unusual action, issued a denial. That led about 70 journalists at the paper to sign a statement complaining that "readers have become completely indifferent to our newspaper."

Journalists at Dong-a Ilbo and Hankook Ilbo have signed similar pledges to defend press freedoms.

Despite the changes, many South Koreans continue to see newspapers as a tool of the government. Many areas of reporting remain off limits, especially when they relate to Chun personally.

During the weeks of street demonstrations, newspapers made little effort to uncover details of Chun's role in responding to the crisis, for instance. Some Koreans believed that the newspapers were fundamentally unwilling to directly criticize his handling of the situation.

Reporters sometimes were taunted in street crowds. It was common to hear demonstrators complain that newspapers systematically underplayed their numbers.

Last month, rioters outside Seoul's main railroad station burned 45,000 copies of the Kyunghyang Shinmun, another government newspaper. The newspaper's reporters, afraid of becoming targets, issued a joint statement saying they favored full press freedoms.

Demonstrators were more angry generally at the country's two television networks, Korea Broadcasting System and Munhwa Broadcasting Corp. KBS' evening news usually begins with long reports of what Chun did during the day. During the protests, most demonstrators assumed that KBS camera crews handed over their tapes to police and intelligence agencies for identification of people taking part.

During demonstrations in Pusan, protesters attacked the local KBS station. In Seoul, they kicked and struck a car carrying an MBC crew as it left the grounds of Myongdong Cathedral.