Books in copyright can be digitized as an Exception under Clause 52-1(a)(i) – provided it is for private or personal research.

Relevant passage:

52. Certain acts not to be infringement of copyright. —

(1) The following acts shall not constitute an infringement of copyright, namely, —

[(a) a fair dealing*** with any work, not being a computer programme, for the purposes of—

(i) private or personal use, including research;

Explanation. — The storing of any work in any electronic medium for the purposes mentioned in this clause, including the incidental storage of any computer programme which is not itself an infringing copy for the said purposes, shall not constitute infringement of copyright.]

*** fair above only refers to ethical behaviour – such as not falsely claiming a work to be yours. it is not related to page-count.

Reference:

https://copyright.gov.in/Exceptions.aspx