How can I turn intensity image thumbnails from all black to the actual image?

I have a stack of reconstructed 16 bit- gray scale images (resolution unit: 2; 96 dpi hor. & vert. resolution) from an X-ray microtomography scan and when I open the Windows folder they are contained in, their thumbnails appear completely black, rather than being small versions of the actual images.

The images are however view-able only after adjusting the contrast setting in a graphics viewer like IrfanView, or with the Adjust Contrast tool after using the IMTOOL function in MATLAB.

Is there some sort conversion I need perform on these images before they can be viewable without changing contrast, rather just having a black picture?

Thanks