It's hard to make headway in copyright law trying to reason like a regular human being.
Copyright is an artificial constraint on something that is otherwise constrained only by cost of raw inputs and machine labor (even back in the days of setting the lead by hand)... And in that sense, not very constrained at all. The whole thing is an artifice that tries to encourage creation of novel work by couching monopoly on ideas in property law.
This leaves you with a quantum beast that mostly runs on "vibes." To your example: no, illegal, because you made a copy, right there, when you format-shifted. Or yes, because you preserved the total number of instances. Or no, because you moved a tangible format that is easy to preserve singularity on to a hard-to-audit, easy-to-copy format, thus greatly increasing the risk of copyright fiolation. Or yes, because you actually recorded the fact of the position of the ink on the paper in your original copy, and you can't copyright facts ("this is a historical record of what my book looked like"). Or...
Copyright is a ball of string and chewing gum held together by a few explicit laws and many, many centuries of precedent. It's very hard to predict what the end result of a lawsuit in novel territory will be, because it really does come down to "Which faction do the judges think should have more power today?"