How to resize an image with PIL getbbox to the maximum possible size? - image

Question

I'm trying to resize sprites to a 96x96 boundary while retaining the aspect ratio.
The following code:
im.getbbox()
Returns a tuple containing the bounds of the sprite (original backgrounds are transparent), and I am stuck on this next part - I want to take that part of the image and resize it as large as it can possibly go within a 96x96 boundary
Here's an example of some sprites from Pokemon:
Since some are 80x80, some are 64x64, and the largest are 96x96, I would like to effectively select the contents of the sprite with im.getbbox() and then enlarge it to fit on top of a 96px white background.
Could anyone please help? I'm not sure how to maximise it within the bounds
My current code is as follows:
x = 0
for dirname, dirs, files in os.walk(path):
for filename in files:
x+=1
path = dirname + "/" + filename
print(path)
im = Image.open(path)
fill_color = (255,255,255)
im = im.convert("RGBA")
if im.mode in ('RGBA', 'LA'):
background = Image.new(im.mode[:-1], im.size, fill_color)
background.paste(im, im.split()[-1])
im = background
imResize = ImageOps.fit(im, (96, 96), Image.BOX, 0, (0.5, 0.5))
imResize.save("dataset/images/" + str(x) + '.png', 'PNG')
It takes the image and pastes it on to a white background and sets the size as 96px. This is fine for the native 96px images but the aspect ratio of the smaller images is ruined. By being able to enlarge them to the maximum bounds of a 96px image then it should prevent this from happening
Thanks!

Answer 1

ok, made my own pics, here:
zY28f_64.png, zY28f_80.png , zY28f_96.png
ended up with code :
from PIL import Image, ImageOps
import os
path= 'images'
x = 0
for dirname, dirs, files in os.walk(path):
for filename in files:
x+=1
path = dirname + "/" + filename
print(path)
im = Image.open(path)
im.show()
fill_color = (255,255,255)
im = im.convert("RGBA")
if im.mode in ('RGBA', 'LA'):
background = Image.new(im.mode[:-1], im.size, fill_color)
# background.paste(im, im.split()[-1])
background.paste(im)
im = background
im_inv = ImageOps.invert(im) ### make white background black
imResize = ImageOps.fit(im.crop(im_inv.getbbox()), (96, 96), Image.BOX, 0, (0.5, 0.5)) # im.crop crop on box got from image with black background, Image.getbbox works only with black bacground returning biggest box containing non zero(non black ) pixels
imResize.show()
# imResize.save("dataset/images/" + str(x) + '.png', 'PNG')
output:
zY28f_64.png2.png , zY28f_80.png1.png , zY28f_96.png3.png
main changes here:
make white background black
im_inv = ImageOps.invert(im)
im.crop crop on box got from image with black background, Image.getbbox works only with black background returning biggest box containing non zero(non black ) pixels
imResize = ImageOps.fit(im.crop(im_inv.getbbox()), (96, 96), Image.BOX, 0, (0.5, 0.5))
Since ImageOps.fit(...) line return chopped images, not sure how it works, to keep the entire figures I used code from PIL Image.resize() not resizing the picture to get:
from PIL import Image, ImageOps
import os
import math
path= 'images'
x = 0
for dirname, dirs, files in os.walk(path):
for filename in files:
x+=1
path = dirname + "/" + filename
print(path)
im = Image.open(path)
fill_color = (255,255,255)
im = im.convert("RGBA")
if im.mode in ('RGBA', 'LA'):
background = Image.new(im.mode[:-1], im.size, fill_color)
# background.paste(im, im.split()[-1])
background.paste(im)
im = background
im_inv = ImageOps.invert(im)
imResize = im.crop(im_inv.getbbox())
width, height = imResize.size
print(width, height)
if height > width:
ratio = math.floor(height / width)
newheight = ratio * 96
print(imResize, ratio, newheight)
imResize = imResize.resize((96, newheight))
else:
ratio = math.floor(width /height )
newwidth = ratio * 96
print(imResize, ratio, newwidth)
imResize = imResize.resize((newwidth, 96))
imResize.show()
print(imResize.size)
imResize.save(path + str(x) + '.png', 'PNG')
output:
zY28f_64.png2.png , zY28f_80.png1.png , zY28f_96.png3.png