Scene optimiser needs to be on, I know that much. Works for me occasionally but it's really hit and miss. I recommend Adobe Scan personally.
No matter how many times I open and close the camera, or turn scene optimizer on or switch document scanner on or off, It will only work sometimes! How can I activate it manually or guarantee it will work. I scan two pages of a 5 page book and it stop. It happens often this way.
I'm still having major issues getting my document scanner function to work. It used to work all the time, but since last few updates, my S10 won't offer document scan under any circumstance. Very annoying, as was a great feature.
I have the Scene Optimiser on and the Motion Photo off.
Suggest Document Scanner is offered as a manual selection under 'More' camera modes selector, on bottom of camera screen. Any suggestions?