The convert tool is used to convert pictures from one format or size to another. The easiest method is to simply convert an image from one format to another using:
$ convert image.jpg image.png
This will convert image.jpg from a JPEG to a PNG and save it as image.png.
To convert and resize an image, use:
$ convert -size 50x50 image.jpg image.png
This will convert from JPEG to PNG format and resize the resulting image to 50x50 pixels. Likewise, you can use convert to rotate an image:
$ convert -rotate 90 image.jpg image.png
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