convert - convert between image formats, resize, blur, crop, despeckle, dither, draw on, flip, join, re-sample, and much more.
Resize an Image (keeping the aspect ratio):
convert my_image.jpg -resize 800x600 new_image.jpg
Resize an Image (ignoring the aspect ratio):
convert my_image.jpg -resize 800x600! new_image.jpg
Resize only the width of an image:
convert my_image.jpg -resize 800 new_image.jpg
Resize only the height of an image:
convert my_image.jpg -resize x600 new_image.jpg
Convert png to jpg or jpeg:
convert my_image.png my_image.jpg
Convert jpg to gif:
convert my_image.jpg my_image.gif
Convert bmp to jpg:
convert my_image.bmp my_image.jpg
Convert tiff to jpg:
convert my_image.tif my_image.jpg
Compress or reduce image file size:
convert my_image.jpg -quality 85 new_image.jpg
Rotate an image 90 degrees:
convert myimage.jpg -rotate 90 new_image.jpg
Rotate image 180 degrees:
convert myimage.jpg -rotate 180 new_image.jpg