jt to jpg conversion represents export of previews of 2D views of a model saved in JT Open format (.jt) as a plain JPEG picture (.jpg, .jpeg). Many 3D modeling tool offer some kind of preview export function, which means that any decent program that works with JT format should also be able to help you to convert jt to jpg.
Open JT file Open JPG fileA 3D product data optimalization software
A 3D CAD translation software