Question to "Confirm" Message for Jpeg lossless transformations

[herb]

Hello Pierre,

I am working with XnViewMP 1.3.0 on a Windows 10 system.

For Tools -> JPEG lossless transformations -> Rotate counter clockwise (or other operations) I expect to see a "Confirm"-popup message "JPEG lossless operation will modify original file ...".

But I have *.jpg images for which this message is displayed and I have images for which this message is not displayed.
Now my question is: why is this message not always displayed?

Best regards
herb

[xnview]

for which file it's not displayed?

[herb]

Hello Pierre,

Thanks for looking into this. Because the image is to big to be attached here, I will send it via mail.

Best regards
herb

[xnview]

When image size is not a multiple of 16, you have the message...

[herb]

Hello Pierre,

thanks for your reply.

But as the confirm-popup message states 2 things:
- original file will be modified AND
- some pixel might be removed (depending on image size)
I thought that it will be displayed for all images.

Best regards
herb