A man has been jailed for two years for defacing a painting by artist Mark Rothko.
Wlodzimierz Umaniec, 26, also known as Vladimir Umanets, defaced the mural, worth in the region of £5 million to £9 million, at London's Tate Modern gallery on October 7 this year.
Umaniec, a Polish national living in Worthing, West Sussex, admitted criminal damage to the value of in excess of £5,000 - but estimates suggest the restoration of the painting will cost around £200,000.
Judge Roger Chapple, at Inner London Crown Court, told Umaniec: "Your actions on the 7th of October of this year were entirely deliberate, planned and intentional."
The vandal, who co-founded the artistic movement "yellowism", stepped over a barrier in the art gallery and daubed his name and the words "12 a potential piece of yellowism" before fleeing.
The court heard that he went to the gallery intending to put his "signature" on a picture, but decided to damage the Rothko painting only at the time he saw it on display.
The gallery was then put into "operation shutdown" with people prevented from leaving or entering the building.
Speaking about "yellowism", Judge Chapple said it was "wholly and utterly unacceptable to promote it by damaging a work of art" which he called a "gift to the nation".
He said it was "abundantly clear" that Umaniec was "plainly an intelligent man" and told the court he had described Rothko as a "great painter" in a letter he had written to him. The judge also said the incident had led to galleries reviewing security arrangements at a cost to themselves and the taxpayer.
Gregor McKinley, prosecuting, said: "Sotheby's has given Tate Modern a verbal estimate of pre-damage value of approximately between £5 million to just over £9 million."Mr McKinley said the complex work to restore the painting will take about 20 months and cost "something around £200,000".