JPG lossless rotate is 180 off

[everything]

JPG lossless rotation is not working on a few specific photos: when I choose 90, I get 270, and when I choose 270, I get 90. I have been using these rotations for years with no problem.

These are photos I took of pages in a book with the book lying on a table and the camera pointing straight down and sometimes the camera was rotated either left or right to give Portrait orientation. The book pages have photographs of rooms but they are murky and unclear, and there is *no* text. Could this have caused problems with how the camera decides the orientation?

I tested a few other unrelated photos (not of book pages) and lossless rotation is working fine.


Ifranview 4.35
Win 7 Pro 64 bit
Canon Powershot S100

[Bhikkhu Pesala]

I don't have a camera, but I guess they use a sensor to determine the orientation in which the camera is being held. If you're pointing straight down on the book, it seems obvious that the camera's sensor won't know which way is up.

Try standing the book on a lectern or book rest while taking the photos. It might also be easier to do.

[jazzman]

Presumably you have the display option "Auto-rotate image according to Exif" activated. So what you see isn't the actual orientation of the image and you will apply the wrong orientation amount.



If you want to delve deep into this, there are several threads discussing the pros and cons of the settings, e.g. https://irfanview-forum.de/showthread.php?t=10057

[Mij]

Jazzman, if you look you will see that the thread you linked to was started by the same person as this one (Everything).
Bhikkhu Pesala, I think that most modern cameras now have 3-axis sensors so they do know they are pointing down. You are correct though that they cannot tell in that state whether the camera has been rotated, so when pointing down they usually just leave the EXIF tag set to Top Left all the time.
Everything, you might like to consider what would happen if you mounted your camera on a tripod pointing down at your book. If you stand behind what you normally consider to be the the bottom of the camera you will see on the screen what you think of as a Landscape image. If you walk around to one or other side of the camera you will see what you think of as a Portrait image. The camera has not moved though, only you. Cameras are not yet equipped with sensors that detect which side the photographer is standing. That is probably next year's technology.