This paper presents a method for evaluating electromagnetic (EM) emanation from displays without screen image reconstruction. Our method focuses on low voltage differential signaling (LVDS), which is widely used in laptop PCs and tablets. We evaluate the EM leakage by changing the display color. The concept of our proposed method is to utilize LVDS by displaying a specific image to control the EM emanation at the leakage frequency. By detecting the controlled emanation as an audible frequency range signal, the leakage frequency can be estimated. We experimentally confirmed that the EM emanation at the intended audible frequency range signal with the proposed method was approximately 6-13 dB greater than that with the conventional method. We demonstrated that our method can estimate EM leakage even with high background noise.