An EMCCD-based dual modular x-ray imager was recently designed and developed from the component level, providing a high dynamic range of 53 dB and an effective pixel size of 26 μm for angiography and fluoroscopy. The unique 2 × 1 array design efficiently increased the clinical field of view, and also can be readily expanded to an MxN array implementation. Due to the alignment mismatches between the EMCCD sensors and the fiber optic tapers in each module, the output images or video sequences result in a misaligned 2048 × 1024 digital display if uncorrected. In this paper, we present a method for correcting display registration using a custom-designed two layer printed circuit board. This board was designed with grid lines to serve as the calibration pattern, and provides an accurate reference and sufficient contrast to enable proper display registration. Results show an accurate and fine stitching of the two outputs from the two modules.