Convert a Color to Transparent with ImageMagick

#Remove the background color from an image
#get the color of the first pixel
magick img.bmp -format "%[hex:p{0,0}]" info:

#convert the image to a png
#and use the color of the first pixel as the transparent color
for img in *.bmp
do
  echo "${img%.bmp}"
  magick "$img" -transparent "#%[hex:p{0,0}]" "${img%.bmp}.png"
done