Image Rotator & Flipper

What this tool is used for

• Fixing a photo that came off a phone or a scanner in the wrong orientation.
• Flipping a scanned page that was fed in backwards.
• Rotating a screenshot taken in the wrong orientation before attaching it.
• Mirroring an image for a layout that reads in the other direction.
• Correcting an image whose EXIF orientation is being ignored by the destination.

Frequently Asked Questions

Is rotating by 90 degrees lossless?

For a JPEG it can be, using a lossless transform that reorders the 8x8 DCT blocks without re-encoding — but only if both dimensions are multiples of 8. Otherwise, and for arbitrary angles, the image is re-encoded and loses quality.

Why does my photo appear rotated already?

Because of the EXIF orientation tag. The pixels are stored unrotated and the viewer applies the tag — so a tool that ignores it shows the photo sideways, and one that strips EXIF without baking in the rotation produces the same fault.

What happens at angles other than multiples of 90?

Every pixel is resampled onto a new grid, softening the image, and the canvas must grow to fit the rotated rectangle — leaving triangular empty corners that are filled, cropped or made transparent.

How is rotating different from flipping?

Rotation preserves handedness; flipping mirrors it. A 180° rotation is not the same as flipping both axes in terms of text — flipped text reads backwards, rotated text reads upside down.

Does this happen in my browser?

Yes, via canvas, so the file never leaves your machine. That is worth knowing for the photos people actually rotate — scanned documents and phone pictures that often carry GPS metadata.

Can a JPEG be rotated without re-encoding?

Yes, by multiples of 90, using a lossless block transform — the DCT blocks are rearranged rather than decoded. It requires dimensions that are a multiple of the block size, which is why some images lose a sliver of edge.

What happens to EXIF orientation after rotating?

It has to be reset, or viewers apply it again on top of the rotation you just made. A file rotated correctly and left with its original orientation tag appears rotated twice in some applications and once in others.

Common errors and gotchas

• Relying on EXIF orientation rather than rotating the pixels, since many tools ignore the tag entirely.
• Rotating a lossy image and re-encoding it, which adds artefacts for a change that should be free.
• Confusing a flip with a 180-degree rotation, which differ for anything containing text.
• Rotating by 90 degrees and forgetting the width and height swap, which breaks a fixed layout.
• Applying a second rotation to correct the first, when going back to the original is cleaner.