1. A computerized method to automatically determine an acquisition volume from which a magnetic resonance data set is to be acquired, said method comprising: operating a magnetic resonance data acquisition unit to acquire at least one preliminary magnetic resonance data set that at least partially encompasses an examination region of a subject; in a processor, reconstructing multiple magnetic resonance images from said at least one preliminary magnetic resonance image data set; in said processor, automatically segmenting the examination region from each of said multiple magnetic resonance images, thereby obtaining multiple segments of said examination region; in said processor, projecting said multiple segments of said examination region into a projection plane; in said processor, automatically determining an envelope that encloses the multiple projected segments of said examination region; in said processor, automatically determining at least one rectangle that includes said envelope; in said processor, automatically calculating the acquisition volume using said rectangle; and in said processor, automatically generating, from the acquisition volume calculated using the rectangle, a protocol for operating said magnetic resonance data acquisition unit, said protocol including specifications of respective coding directions for readout, phase coding and slice selection gradients needed to acquire the calculated acquisition volume, and making said protocol available at an output of said processor in an electronic form configured to operate the magnetic resonance data acquisition unit.