then storedStructure will have 3 fields, one that contains each variable you saved. You can get then back to individual variables from the structure if you do this
To convert images to .dat format see the link below:
You can also use the ImajeJ software. Upload the image (I mean 2D), then go to Analyze tool bar, then Tools and Save X,Y coordinates. It will generate a txt file with X,Y coordinates and pixel values.
I hope it help you as other colleagues referred to matlab.