Lossless rotation makes incorrect change.

[calberga]

For some time when I apply a clockwise lossless rotation to a .jpg file (from either camera, scanner, or iPad/iPhone) the result is a 180° rotation. I must then apply a counter-clockwise rotation to get the desired result. This has persisted through several updates. Any ideas? Bad Feng shui?

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[IfThenElse]

Is the problem that Windows is showing the incorrect rotation in the original thumbnail in File Explorer? I have had this problem with some camera images.

I normally get Windows to correct its understanding of the orientation and update its thumbnail by right clicking on the file and selecting Rotate Left or Rotate Right.

You may need to experiment to find what works.

[j7n]

I suspect that the image has a rotation tag in it, and it is automatically rotated upon opening. But a hard rotation must strip this tag.

[JendaLinda]

Lossless JPEG rotation has the ability to rebuild thumbnails embedded in JPEG files. Check out the options.
Windows explorer uses its own thumbnail database. Supposedly Windows will update thumbnails only if it notices the files have changed by comparing file timestamps.

[calberga]

All of my observations have been in IrfanView Thumbnails, none in Windows File Explorer. I'm taking the .jpg files straight from my iPhone to a hard-drive and then opening in IrfanView. Besides, I have seen the same behavior in images from point-and-shoot cameras, also with no interaction with Windows File Explorer.

j7n -- What should I look for to see a "rotation tag"?

[calberga]

One other comment -- I have seen this behavior when preforming lossless rotations on image in the straight IrfanView program, rather than on the image in the Thumbnails view.