Hakimzadeh was born in Iran but is a British national
An Iranian scholar who stole pages from priceless books at Oxford's Bodleian library and the British Library has had his sentence halved.
Farhad Hakimzadeh, 61, of Knightsbridge, central London, pleaded guilty to 14 counts of theft and was jailed for two years in January 2009.
Judges at the Appeal Court reduced the sentence to 12 months and a deportation order was overturned.
The British Library said it was disappointed with the court's ruling.
The court heard Hakimzadeh had cut leaves out of precious works and inserted them into his own copies.
Police found the altered editions along with several loose pages in the library at his home.
British Library staff believe he smuggled a scalpel into the building and positioned himself away from security cameras to commit his crimes.
The books dated to the 16th Century and all concerned European engagement with the Middle East.
William Boyce QC, for the scholar, pleaded his "philanthropic and charitable works" in mitigation, asking for his jail term to be decreased.
Mr Justice Blake, giving the court's judgement, said: "This was not a case of someone stealing to improve his library then preventing scholars from accessing those books in the future. All the books have been recovered and so have the pages.
"He has suffered a considerable humiliation and loss of reputation at the age of 61 years."
The decision means that Hakimzadeh, having served 104 days, will be released in 78 days time.
A spokesman for the British Library said: "When Hakimzadeh damaged and stole pages from Library items he abused the trust that we extend to all researchers using our collections.
"We have zero tolerance of anyone who harms our collections and will pursue anyone who threatens them with utmost vigour."
The spokesman added that the Library will "continue to pursue a number of routes with the aim of achieving redress for the damage he caused."