How to resize an image in Linux with convert from ImageMagick.

Use the command convert.

If you get command not found opt to install the package if it shows Install package 'ImageMagick' to provide command 'convert'

The output will show something similar to this:

The following packages have to be installed:
 ImageMagick-1:  An X application for displaying and manipulating images
 ImageMagick-libs-1:     ImageMagick libraries to link with
 graphviz-2.50.0-6.fc36.x86_64  Graph Visualization Tools
 gts-0.7.6-41.20121130.fc36.x86_64      GNU Triangulated Surface Library
 lasi-1.1.3-8.fc36.x86_64       C++ library for creating Postscript documents
 libXaw-1.0.14-2.fc36.x86_64    X Athena Widget Set
 liblqr-1-0.4.2-19.fc36.x86_64  LiquidRescale library
 libwmf-lite-0.2.12-8.fc36.x86_64       Windows Metafile parser library
 mkfontscale-1.2.1-4.fc36.x86_64        Tool to generate legacy X11 font system index files
 netpbm-10.97.00-2.fc36.x86_64  A library for handling different graphics file formats
 xorg-x11-fonts-ISO8859-1-100dpi-7.5-33.fc36.noarch     A set of 100dpi ISO-8859-1 fonts for X

After installing, it might show:

Version: ImageMagick 6.9.12-50 Q16 x86_64 17254
Copyright: (C) 1999 ImageMagick Studio LLC
Features: Cipher DPC Modules OpenMP(4.5)
Delegates (built-in): bzlib cairo djvu fontconfig freetype gslib gvc jbig jng jp2 jpeg lcms lqr ltdl lzma openexr pangocairo png ps raqm raw rsvg tiff webp wmf x xml zlib
Usage: convert [options ...] file [ [options ...] file ...] [options ...] file

You can also see the docs with either of these commands

$ man convert
$ convert -help

I use convert to resize a screenshot of a burndown chart from Jira to fit the dimensions of the Linkedin profile header.

Use the exclamation point to fix the width and height, otherwise it will autoscale the height.

$ convert screenshot.png -resize 1584x396! li-background.png