@uploader Use XnViewMP, it's free 1. Download and install 2. Navigate to the folder with the images that need rotation 3. Highlight all the images that are in the wrong orientation (use shift and/or ctrl and click) 4. Top Menu -> Tools --> JPEG Lolless Transformations ---> Rotate images counter clockwise
This method does not recompress the jpegs so it won't lower image quality Instead it adds a metadata instruction into each jpeg telling image viewers to rotate before rendering the image onto your monitor.