Hi @Pizza_Sub_Pizza,
Im afraid that there will not be an easy ‘casting’ way for what you want to do.
What you can do though is to create a new 
Image with the desired PixelFormat and the use LinearAccess to write the values from your 16bit image into this image.
See:
https://forum.commonvisionblox.com/t/writing-pixel-values-to-an-array/196/7
Cheers
Chris