The official China News Net published an article based on interviews with Chen Shilin, translated by CDT:

Chen Shilin is a high-ranking technician in the China Photographic Association. In the past he served as group director of the Xinhua News Agency photography department technology group, Renovation Group director, and director of the National Political Leadership Photography Work Group. At that time, other than Chairman Mao’s official portrait, Chen Shilin also retouched all national leaders’ photographs including those of Zhou Enlai, Liu Shaoqi, Zhu De and Lin Biao.

At age 10 Chen Shilin was sent by his father to apprentice at the Nanjing Photographic Studio. After this he went to Hong Kong and Taiwan to study the skill of retouching photographs. In July 1950, Chen Shilin returned to the Mainland. At that time there were very few people who knew how to retouch photographs. He also could alter the light of a photograph, and adjust its density and three-dimensional effect. For this reason Chen Shilin was identified as a person of talent, and entered the Central News Photography Bureau. Later he entered the Xinhua News Agency’s photography department, and enjoyed similar preferential treatment to that of old revolutionaries from Yan’an, eating special food and being provided special living arrangements.

He was fortunate to have been chosen to prepare Chairman Mao’s official photographic portrait, and put his skill to its maximum use.

More excerpts from the article, selectively translated by CDT:

… Chen Shilin recounts that photographing Chairman Mao was a challenge. He was always so busy and tired. You couldn’t tell him to go brush his teeth and make them nice and white! In photographing Chairman Mao, we had to make certain arrangements and slightly retouch the photographs, but that’s all. If his teeth came out black in the original photo, this did not accord with essential truth, which is that the Chairman’s teeth were white, so I retouched the photo to turn black-looking teeth into white ones thus according with essential truth.

… Chen Shilin relates that in those special years because of political circumstances some photographs had to have major overhauls performed on them. For example, in those years the Xinhua News Agency published a photo of Chairman Mao, [Mao’s heir apparent] Liu Shaoqi, Deng Xiaoping etc. all attending a conference together. But for some reason the photographer did not include Deng Xiaoping in the original photograph. So we had to come up with a quick fix. So in the processing stage, we removed the head of Marshal Chen Yi–who was in the original picture–and replaced it with the head of Deng Xiaoping!

… Chen Shilin gradually came up with a method for his work. To let the photograph “most resemble” Chairman Mao, he let the leader’s charisma be tacitly expressed, and reflect the deep respect that the people had toward their leaders. The photographs had to reflect carefully observation, draw on strong points to offset weaknesses, and project a strong personal aura. Like the halo around Chairman Mao’s head, it had to be light in just the right places. And the wrinkles in his forehead had to express wisdom, if they radiated a little light it was best. And in his later years the bags under the Chairman’s eyes became increasingly pronounced. This was best to soften a little. And Chairman Mao’s eyes were originally very bright. But in his later years they became turbid, so it was necessary to lighten the whites of his eyes.

… There is also one thing that Chen Shilin did not talk about, and only later in life revealed: “At that time when I received a picture of Chairman Mao, I felt that it was my obligation to make him look like a great man.” In Chen Shilin’s view, pictures that were overly realistic were failures: Chairman Mao’s eyes were not bright, as he got older they became dimmer, and his clothes were in shadow, and his collar was not straight. But Chen Shilin’s skill was such that he could retouch the photograph so that it made the Chairman look younger than the third official photographic portrait of Chairman Mao made five years earlier, with his hair darker and wrinkles less pronounced.

… Chen Shilin began work on the fifth official photographic portrait of Chairman Mao. This was in his later life when Chairman Mao’s health was in rapid decline. No matter how the picture was retouched, he could not summon the image of a great leader. No matter how he tried, when you looked at the picture you did not see “the great Chairman.” So Chen Shilin abandoned the effort and gave up in frustration.

… Chairman Mao died in 1976. As a “representative of the masses,” Chen entered the Great Hall of the People and looked upon Chairman Mao’s remains and was wracked with sadness. Although he had retouched the Chairman’s photographs for half his life, this was the first time that he had been in such close proximity to the Chairman. The Chairman was made up with rouge to look like he was still alive. Chen Shilin thought to himself that although the Chairman looked good even in death, he did not resemble his official photographic portrait.