Herein, a new imaging-transformation method for acquiring a measurement matrix is proposed. A visible light camera is used to capture amplitude-modulated plate pattern information, then a coherent imaging algorithm is used to obtain the simulated light field, and finally the simulated light field is transformed into a ghost imaging measurement matrix. We validate the feasibility of this imaging-transformation method using an established terahertz ghost imaging system. Experimental results show that the measurement matrix obtained using the proposed method can enable terahertz ghost imaging to reach diffraction limit resolution. The resulting image quality is superior to that obtained using the classical scanning method. In addition, we experimentally study the influences of sampling frequency, pupil function, and matrix resolution on the final image quality.