Resize and increase the canvas size of an image to 225x100 using imagemagick

resize_image_increase_canvas_size

# I want to resize an image  from 600x128 to 225x100 while keeping its aspect ratio.
# Resizing the width to 225 while keeping the aspect ratio makes one dimension (height)
# smaller (225x48) than what I want to obtain (225x100).

# The workaround is to resize first, 
# then increase the canvas of the other dimension (height)
# to obtain the desired size (225x100) then center the image in the canvas.


#~~~~~~~~~~~~~~~~~~~~~
# Step #1: Resize the width first to 225 keeping the aspect ratio (=> 225x48)
# This is not enough.
#~~~~~~~~~~~~~~~~~~~~~
convert image_600x128.png  -resize 225  image_225x.png

#~~~~~~~~~~~~~~~~~~~~~
# Step #2: Now increase the canvas size setting height to 100 and center the image
# ~~~~~~~~~~~~~~~
convert image_225x.png  -gravity center -extent 225x100   -transparent white  image_225x100.png