SQLite Forum

How to READ and WRITE an image to an SQLITE BLOB FIELD
The reference material says:

7.3. File I/O Functions<br />

The command-line shell adds two application-defined SQL functions that facilitate reading content from a file into a table column, and writing the content of a column into a file, respectively.

So, those functions are part of the SQLite shell, and are not in the SQLite library by default. The SQLite library that PHP offers will not have them either, because it doesn't need them.

You will have to use PHP functions to read the image into memory and bind it as a BLOB to your prepared INSERT statement, and the other way around for SELECT.