Convert Image type

Imagemagick

Single

convert           \
   -verbose       \
   -density 150   \
   -trim          \
    test.pdf      \
   -quality 100   \
   -flatten       \
   -sharpen 0x1.0 \
    24-18.jpg

Directory

Batch converting PNG to JPG in linux

for i in .png ; do convert “$i” “${i%.}.jpg” ; done

Crop

Imagemagick

convert stereo0000.png -crop 50%x100% foo.png

convert -crop 800x1000 image.png cropped_%d.png

convert stereo*.png -gravity East -crop 50%x100%+0+0 right%04d.png
convert stereo*.png -gravity West -crop 50%x100%+0+0 left%04d.png

Warning! This one is the most effective but also potentially destructive:

mogrify -crop 50%x100% +repage -path ./cropped *.png

(+repage resets image geometry)