We conducted experiments on a real STEM-EDX data with low X-ray counts. The sample was prepared using a commercially available SiC power MOSFET. The resin mold of the sample was removed using a chemical etching process. A section was then fabricated by focused ion beam milling. The sample's bright-field image, as shown in the left of Figure , was obtained using a Hitachi HD-2700 scanning transmission electron microscope with 200 kV of acceleration voltage. The EDX spectral image data of 50 ˆ50 " 2500 pixels by 4096 energy channels with 0.01 keV resolution was obtained by using a silicon drift detector with 140 eV of energy resolution, 21.9 degrees of X-ray take-off angle with the JEOL JEM-ARM200F with 200 kV of acceleration voltage, and 0.2 nm of beam diameter. For a reference, we roughly annotated the three main components as three regions in Figure on the right, based on the contrast of the bright field image and a manual elemental mapping analysis. In our numerical experiment, we used 250 channels from 0.11 to 2.6 keV, since the channels of higher energy are redundant with no signature. The lower limit of the energy channel was determined to properly apply wPCA , since it requires the data to have nonzero intensities, and otherwise, the rescaling becomes singular. Note that the proposed method itself can even be applied for data with zero intensities. We thus used the EDX spectral image data matrix with a size of 250 pchannelsq ˆ2500 ppixelsq in the following numerical experiment.