Why can't I open all the files on the SD card from the CI-203?

There are two files transferred for each data file on the SD card in the CI-203. One file contains the spreadsheet with measurement data such as length/area/width information. The other file is an image data file.  

The .img file holds the information that the data file shows in numbers. Also, if there is no data in a file, the file name will still appear on the SD card.