Flip an image vertically

A vertical reflection is a scale of minus one on y with a translation of the frame height. Every column is read from the bottom up; every row keeps the order it had. It is the same class of operation as the horizontal case and it costs exactly as little, but people reach for it far less often, and when they do it is usually for a reason that has nothing to do with photographs.

The interesting property is what it does to text. A horizontally reflected word is unreadable because the letters are in the wrong order. A vertically reflected word is unreadable because each letter is upside down while the order is preserved — the eye can still parse the shape of the line, which is why a vertical reflection of a document looks wrong in a subtler and more disorienting way than a horizontal one.

1. 1Open the file. This page starts on the vertical axis, so the right-hand panel already shows the reflection when the file lands.
2. 2Compare deliberately. The divider wipes across the frame rather than down it, which is the awkward direction for this axis. Holding Space to see the whole original is usually the faster check here.
3. 3Save it. Container, then Save mirrored file. Nothing between the panel and the file changes except resolution.

Reading covers JPG, PNG, WebP, AVIF, GIF, BMP, TIFF and ICO wherever the browser will decode them, with HEIC handled by a WebAssembly codec that is only fetched when one is opened. Writing covers JPEG, PNG and WebP, because those are the three a browser can produce. Metadata other than the orientation flag is carried into JPEG and PNG exports; a WebP export is written clean.

• This is not the operation that puts a picture the right way up. If a photograph arrived upside down, both axes are wrong, and the fix is a turn rather than a reflection. Turning is not built here and will not be: it is a different product with a different set of edge cases, and doing it badly on the side would be worse than not doing it.
• A reflected scene is no longer evidence of anything. The vertical case is less obvious than the horizontal one and therefore easier to miss. Shadows fall upwards, water sits above the shoreline, and light that came from a window now comes from the floor. Nothing on this page detects that; you have to.

Is a vertical flip the same as turning the picture upside down?

No, although the two are almost always confused. Turning a picture over reverses the rows and the columns together; a vertical reflection reverses only the columns. Take a photograph of a page of text: turn it over and the text is upside down but still in the right reading order, reflect it vertically and the letters are mirrored top to bottom while the words still run left to right.

Why would anyone want a vertical flip?

Three cases account for most of it. Making a water-style reflection under a subject, where the copy underneath has to be reversed on this axis. Correcting artwork that a scanner, a plotter or a laser cutter fed through the wrong way. And producing a transfer for a surface that is loaded from the far edge rather than the near one, where the press reverses this axis instead of the other.

Does a vertical flip fix a picture that looks upside down?

Only by coincidence. If the picture is upside down, both axes are reversed, and the operation that returns it is a turn rather than a reflection. Reflecting on this axis alone will leave you with a picture that is the right way up and back to front.

Is anything lost?

Not by the transform. Columns are re-addressed, not resampled, and running it twice gives you the original grid back. The export is where a JPEG picks up another generation of compression, and PNG avoids that at the cost of size.

What happens to the EXIF orientation flag?

It is resolved on the way in and reset on the way out. Four of the eight orientation values are themselves mirrored states, so a file that arrived with one of those has already been through a reflection before this tool saw it. Normalising first and writing orientation one afterwards is the only way the result looks the same in every viewer.