JOHANNESBURG — With giant portraits of Nelson Mandela and colorful posters, South African artists are celebrating the 95th birthday Thursday of the anti-apartheid leader, who remains hospitalized although his condition has improved.

The “father of the nation” has inspired many artists to create works to commemorate the Nelson Mandela International Day, a day declared by the United Nations as a way to recognize the Nobel Prize winner’s contribution to reconciliation.

Paintings and posters depicting Mandela have sprung up around Johannesburg in tribute to the life of the ailing icon, some on a very large scale.

Artists John Adams and Paul Blomkamp created two of the biggest Mandela paintings in tribute to the iconic leader for his years of public service to his community. They say their paintings reflect the scale of Mandela’s global contributions and the exceptional energy of the anti-apartheid leader.

Adams said his portrait of Mandela — at 4.8 x 4.5 meters (16 x 15 feet) — is the largest that exists of the anti-apartheid leader. The 38-year-old, who painted the portrait at his childhood home in the Johannesburg suburb of Bosmont, said Mandela inspired him as a young artist.

“The moment he was released, schools were opened to everybody,” said Adams, who is of mixed race and got new educational opportunities with the end of apartheid. “It was momentous to me because the extra bit of education really impacted my life dramatically … I started really understanding what art is and the degrees to which you can really extend and improve yourself as an individual.”

Adams’ painting features Mandela waving with the African continent in the palm of his hand, as people in the background cheer the former president’s contributions. It will also include some of Mandela’s famous words.

The painting will be exhibited at Johannesburg’s concert arena, the Coca-Cola Dome, from July 24 to 27 and then will be auctioned to raise funds for South African charities for abused children, the Teddy Bear Clinic and Sunlight Safe House.

A “labor of love” is how artist Paul Blomkamp describes his portrait of Mandela. Blomkamp spent 14 months painting vibrantly colored stripes that form a smiling Mandela face, which he said was inspired by the iconic figure’s exceptional energy.

“I wondered how he arranged his energy so he could be so great and give so much to the world,” said Blomkamp.

The painting at 4.2 by 4.2 meters (14 x 14 feet) is too large to fit in Blomkamp’s Rivonia home studio, so he has created it in panels. He hopes the painting will one day be housed at a planned children’s hospital to be named after Mandela.

Blomkamp said his painting will be featured in a display in New York’s Times Square Thursday in honor of Mandela’s birthday, a tribute he considers worthy of the leader’s global impact.

“I don’t want his work to be forgotten,” said Blomkamp. “So we’ve got to do something big.”