Convert

Image modification on the command line.

Geometry

Format	Meaning
scale%	Scale the image, by x percent
scale-x%xscale-y%	Height and width are scaled individually by x / y percent
width	Height automatically adjusts to maintain aspect ratio
xheight	Width automatically adjusts to maintain aspect ratio
widthxheight	Scale to fit in the box widthxheight, maintains aspect ratio
widthxheight^	Scale to used box widthxheight as minimum sizes, maintains aspect ratio
widthxheight!	Resize to widthxheight, aspect ratio ignored
widthxheight>	Shrinks images larger than widthxheight, to this size
widthxheight<	Enlarges images smaller than widthxheight, to this size
widthxheight{+-}offset-x{+-}offset-y	For example, used with -crop to specify a region to keep

Resize

convert ${FILE_IN} -resize ${WIDTH}x${HEIGHT} ${FILE_OUT}

Crop

convert ${FILE_IN} -resize ${WIDTH}x${HEIGHT}+${OFFSET_X}+${OFFSET_Y} ${FILE_OUT}