The de Blasio administration is using inaccurate renderings in a bid to sway public support for a controversial new jail proposed for the South Bronx, a new study charges.

The 25-story lockup eyed for Mott Haven — which is part of Mayor Bill de Blasio’s larger efforts to shutter the scandal-scarred Rikers Island jail complex by 2027 — is portrayed as significantly smaller and less of an eyesore for surrounding neighborhoods in official documents released by City Hall for a mandatory public review process, according to urban planner George M. Janes.

“The photo renderings of the jail in the [city’s draft environmental impact statement] are terrible,” Janes told The Post Friday. “They show the building in the wrong place at the wrong size.”

“The actual scale of the jail is absolutely enormous, and it will actually tower over this neighborhood,” added Janes, whose firm was hired to prepare the 34-page report by local activists suing the city to block the jail plan.

The urban planner said he believes the “errors” in these preliminary renderings — commissioned and certified by the city’s Planning Commission — occurred because someone took “shortcuts” by slapping a 3-D computer-generated model of the proposed complex onto current photos of the targeted area, rather than combining it with a 3-D digital model of the other existing buildings.

He compared the finished product to using photo-processing software like Photoshop that relies solely on operator judgment.

For example, an eastern view of the proposed jail seen from East 142nd Street and Jackson Avenue in the DEIS seems to show the building predominately hidden behind trees — “when in fact it’s going to tower over those trees and really be a presence in the neighborhood — especially close up within a few blocks,” said Janes.

But City Hall spokesperson Jane Meyer said the renderings “accurately represent our proposed plan to replace the jails on Rikers Island with a smaller, safer, and fairer borough-based system” and “were prepared in accordance with the City Environmental Quality Review technical manual.”

De Blasio last year announced he intends to close Rikers by 2027 and move its detainees closer to courts and their families in every borough except Staten ­Island.

But the plan is facing stiff opposition across the city.