Lossless rotate based on EXIF value results in slight crop

[kaon]

I received a portrait oriented photo from an iPhone4 by email, the dimensions were 478 x 640.
As usual, xnview displays it correctly in portrait orientation while most other applications do not. I gather that this is due to most viewers ignoring orientation via EXIF. So I use xnview's "JPEG lossless rotate based on EXIF value", so that it will display correctly in other applications. I've done this many times, this is the first time I noticed a uncommanded crop. The dimensions changed to 464 x 640.
(xnview ver: 1.98 on Win7.)

[xnview]

Yes lossless rotation use width/height as multiple of 16

[kaon]

Yes lossless rotation use width/height as multiple of 16

Ah, thank you.
Feature suggestions:
- Improve the lossless operations (crops and rotates) so that they can output non-multiple-of-16 outputs

Questions:
In the present version, what is the behaviour of the unintended crops due to non-multiple-of-16:
- For lossless rotate, are the crops equalized from LEFT & RIGHT / UP & DOWN?
- For lossless crops, are the unintended crops conservative or aggressive? Are they equalized from LEFT/RIGHT/UP/DOWN?