imagemagick

Convert jpg to png.

1convert image.jpg image.png

1convert image.jpg -quality 50 image.jpg

'Quality' must be from 1 to 100.

1convert -resize 50% image.jpg image2.jpg

Resizing only changes jpegs. Change a png with:

1convert input.png png8:out.png

Invert Colours

1convert input.jpg output.jpg -negate

Make Images Smaller

1convert image.jpg -resize 25% output.jpg

Trim images to border

This is generally used for transparent images.

1convert -trim image.png output.png

Make the white of an image transparent.

1convert -transparent white -fuzz 10% input.png output.png

The 'fuzz' option tells the computer that 'close to white' is fine. You might want to use 20% or higher fuzz.

Dropshadow

1`convert <input file> \( +clone -background black -shadow 50x8+0+5 \) +swap -background none -layers merge +repage <output file>`

Convert every jpg in directory to png

1mogrify -format png *.jpg

Printing Words

Mass convert

This script converts all jpg files in a directory to svg.

1for i in  *jpg
2do convert "$i" $(ls "$i" | sed s#jpg\$#svg#)
3done

SVG

The above script has crappy results. It's better to use potrace.

1$convert -flatten input.jpg output.ppm
2$potrace -s output.ppm -o svgout.svg

Writing Words

docs

See your installed fonts:

1convert -list font

Make an image showing day of the week:

1convert -fill blue -font Sauce-Code-Pro-Semibold-Nerd-Font-Complete-Mono -gravity center -pointsize 79 label:$(date +%A) day.png

Make a meme:

1convert inputmemeimage.png -font impact -fill white -pointsize 84 -stroke black -strokewidth 3 -gravity north -annotate +0+20 'TOP MEME TEXT' -gravity south -annotate +0+20 'BOTTOM MEME TEXT' outputmemeimage.png