Hello Tomas.
A customised "functional global variable" should be a good solution. My idea is:
(1) Keep the array of images in the shift register of the functional global variable (e.g. as a 3D-NumericArray or as an Array of Cluster of Image).
(2) Allow for reading and writing of
one element of the array by the functional global variable. (= Do not pass the contents of the shift register to the input or output terminals of this VI. The array of images should only "live" in the shift register.)
This solution should be memory friendly and come with a good access time to each image.
Hope this helps, Guenter