Resize rectangular image to square, keeping ratio and fill background with black

Question

I\'m trying to resize a batch of grayscale images that are 256 x N pixels (N varies, but is always ≤256).

My intention is to downscale the images.

The resiz

Answer 1

PIL has the thumbnail method which will scale keeping the aspect ratio. From there you just need to paste it centered onto your black background rectangle.

from PIL import Image

def black_background_thumbnail(path_to_image, thumbnail_size=(200,200)):
    background = Image.new('RGBA', thumbnail_size, "black")    
    source_image = Image.open(path_to_image).convert("RGBA")
    source_image.thumbnail(thumbnail_size)
    (w, h) = source_image.size
    background.paste(source_image, ((thumbnail_size[0] - w) / 2, (thumbnail_size[1] - h) / 2 ))
    return background

if __name__ == '__main__':
    img = black_background_thumbnail('hLARP.png')
    img.save('tmp.jpg')
    img.show()