Oh! Thanks! I thought I'd better look further, and discovered that although the word 'minuscule' has a Latin and French origin, that the alternative 'miniscule' is frequently used.
Here, from stancarey@wordpress: "a minuscule matter of spelling":

"The common prefix mini- has probably lent minuscule a folk etymology that influences its contemporary spelling: miniscule is a popular variant. Pronunciation might also have played a part.

Here are some examples of miniscule I’ve come across in books:

There is even a miniscule dance floor for the perpendicular manifestations of horizontal intentions (Hugh Leonard, A Peculiar People)

Only in the microscopic domains of the atom, or the vast reaches of interstellar space, do miniscule discrepancies between nature according to Newton and nature according to Nature make themselves known. (Ian Stewart, Does God Play Dice? The New Mathematics of Chaos)

So, the alternative use exists and is not condemned. "Mini-" seemed right at first glance because these images are enlargements of "mini-sized" originals. Thanks for the dialogue!