How to use the Image Size tool in Photoshop to set dimensions and resolution of figures/plates; and to set for other outputs (Word, PowerPoint, etc)
How to Set Image Size in GIMP
• Image Size is found under Image > Scale Image. Watch video to see possible mistakes you can make.
How to Set Image Size in Image J
Not recommended because inch and mm dimensions cannot be set. If free is important, use Inkscape and see videos on this site for its use.