A script to resize an image of any size while keeping the original aspect ratio.

inset-crop.py

# A script to resize an image of any size while keeping the original aspect ratio.
# To keep the output size and the aspect ratio, the free space next to the image
# is filled with a given RGBA color.


from PIL import Image
import sys
import re


# open input image path from 1st cli arg
inimg = Image.open(sys.argv[1]).convert("RGBA")
print("image", sys.argv[1], "opened as rgba")

# read input image size and calculate aspect ratio
insize = inwidth, inheight = inimg.size
aspectratio = inwidth / inheight
print("read input image width", inwidth, "and height", inheight, "with calculated aspect ratio (w/h)", aspectratio)

# parse output image size from 2nd cli arg
wstr,hstr = re.findall(r"(\d+),(\d+)", sys.argv[2])[0]
outsize = outwidth, outheight = (int(wstr), int(hstr))
print("will convert to width", outwidth, "and height", outheight)

# calculate in-out image size difference
diffwidth = outwidth - inwidth
diffheight = outheight - inheight
print("in-out image width difference", diffwidth, "and height difference", diffheight)

# get rgba color for inset from 3rd cli arg
clst = re.findall(r"(\d+),(\d+),(\d+),(\d+)", sys.argv[3])[0]
insetcolor = tuple([ int(c) for c in clst ])
print("will inset fill with rgba color", insetcolor)

# get output image path from 4th cli arg
outpath = sys.argv[4]
print("will output image save as", outpath)



# create output image with inset color as background
outimg = Image.new("RGBA", outsize, insetcolor)

# resize input image depending on the orientation
# and place resized image centered on the output image

# for landscape input image
if abs(diffwidth) > abs(diffheight):
    print("input image is in landscape orientation")
    resimg = inimg.resize((outwidth, int(outheight*aspectratio)))
    inset = int((outheight - resimg.height) / 2)
    outimg.paste(resimg, (0, inset))

# for portait input image
elif abs(diffwidth) < abs(diffheight):
    print("input image is in portrait orientation")
    resimg = inimg.resize((int(outwidth*aspectratio), outheight))
    inset = int((outwidth - resimg.width) / 2)
    outimg.paste(resimg, (inset,0))

# for square input image
else:
    print("input image is a square")
    resimg = inimg.resize((outwidth, outheight))

    # save resized square image (no inset needed) and exit
    resimg.save(outpath)
    print("resized input image saved")
    resimg.show()
    exit()

print("resized image composited")

# save composited output image
outimg.save(outpath)
print("output image saved")
outimg.show()