ImageMagick

Command line image editing https://imagemagick.com

Resize image

 magick convert image.png -resize 960x540 image_resized.png

convert original.png -matte mask.png -compose DstIn -composite output.png

 magick convert source.png -fuzz 20% -transparent white result.png

magick -background lightblue -fill blue \
          -font Candice -pointsize 72 label:Anthony \
          label.gif