This tool allows to view embedded thumbnails, which are a part of some jpeg images. Apart of the full size image jpeg-files often contain a thumbnail for previewing the picture on the camera's LCD screen, in file managers, or in photo manipulation software.
You will select a folder to read files. The found thumbnails are presented in a column. The results also contain thumbnail sizes and image paths.
Not all jpeg-files contain thumbnails. Also not all, but typically the majority of thumbnails can be extracted with the tool.