How to add a watermark with ImageMagick

Adding a watermark with ImageMagick marks an exported image without opening a graphical editor. Batch exports, review proofs, and public previews can keep the original image untouched while writing a branded copy to a separate file.

The magick composite command places one image over another. A transparent PNG logo keeps its alpha channel, -gravity southeast anchors it to the lower-right corner, -geometry +32+32 keeps it away from the edges, and -dissolve 45% blends the watermark with the base image.

Use an output filename that differs from the input filename, especially when testing opacity and placement. The commands use a JPEG source and a transparent PNG logo; ImageMagick 7 syntax starts with magick composite, while some older ImageMagick 6 packages expose composite as the command name.

Steps to add a watermark with ImageMagick:

Confirm that ImageMagick can read the source image and watermark image.
```
$ magick identify -format "%f %m %wx%h\n" source.jpg logo.png
source.jpg JPEG 1200x800
logo.png PNG 360x360
```
Use a transparent PNG for the watermark when the logo should keep soft edges or a non-rectangular shape.
Place the watermark in the lower-right corner and save a separate output file.
```
$ magick composite -dissolve 45% -gravity southeast -geometry +32+32 logo.png source.jpg watermarked.jpg
```
-gravity southeast chooses the corner, -geometry +32+32 adds the inset, and -dissolve 45% controls opacity. Increase the percentage for a stronger watermark.

Do not reuse the original filename as the output while testing. ImageMagick writes the result to the output path you provide.
Confirm the source and watermarked files keep the expected format and dimensions.
```
$ magick identify -format "%f %m %wx%h\n" source.jpg watermarked.jpg
source.jpg JPEG 1200x800
watermarked.jpg JPEG 1200x800
```
The visual check matters because identify proves the file dimensions and format, not the final logo placement.