How to Fix a Sideways Photo or Scan
A photo looks fine on your phone, you upload it, and it arrives on its side. Nothing is broken - the file contains a note saying which way up it goes, and the thing you uploaded it to ignored the note. The Image Editor fixes it properly by rotating the pixels.
The orientation flag, and why it fails
When you turn a phone sideways to take a picture, the camera does not usually rotate the image it records. It records the sensor's view and writes a small instruction into the file's metadata: display this rotated ninety degrees. Phones, photo apps and modern browsers read that instruction and show the photo the right way up.
Plenty of other software does not. Older content management systems, some email clients, print services and many image processing libraries read the pixels and ignore the flag. So the same file is upright in one place and sideways in another, and neither is wrong exactly - they just disagree about whether to read the note.
Rotating the pixels settles it. Once the image data itself is the right way round, the flag is irrelevant and every piece of software agrees.
Fixing it
Open the photo in the editor, rotate it until it is upright, and save. What you get back is a file whose pixels are in the orientation you see, so it will look the same everywhere. If you are preparing a batch for a website, this is worth doing before upload rather than discovering the problem afterwards.
While you are there, it is a good moment to consider the rest of the metadata. The same block that holds the orientation flag often holds the time, the camera model and sometimes the location - all visible to anyone who receives the file. The EXIF Data Viewer and Remover shows what is in there.
A photographed document is a different problem
If your scan is not merely sideways but skewed - taken at an angle, with the page edges not parallel to the frame - rotating will not straighten it. That needs perspective correction, which is what the Document Scanner does by letting you mark the four corners of the page.
Common questions
Why did rotating it in my phone's gallery not help?
Some gallery apps only change the orientation flag rather than the pixels, so the file is unchanged and the next piece of software ignores the note all over again.
Does rotating reduce quality?
A quarter turn is lossless in principle, but re-saving a JPEG always costs a little. One pass is not noticeable.
Can I rotate by a few degrees rather than ninety?
Yes, for a slightly tilted horizon. It requires cropping the corners, since a rotated rectangle no longer fills a rectangular frame.
Will this fix a sideways video?
No, video orientation works the same way but needs a video tool.
Need a photo to stay upright everywhere?