MCYT Dataset conversion .fpg to .jpg

I am working on MCYT-100 Signature dataset, and that dataset contains ".fpg" file, and Matlab is not recognizing that file extension, can anyone help me in the conversion of that file to .jpg, .png. i have tried some method of file conversion like * FOR /R %f IN (*.fpg) DO REN "%f" *.jpg* but it is not fulfilling my task. i have also tried to convert this file through online systems but they are also not able to recognize the file extension.