Automatically cropping an image with python/PIL

Question

Can anyone help me figure out what's happening in my image auto-cropping script? I have a png image with a large transparent area/space. I would like to be able to automatically crop that space out and leave the essentials. Original image has a squared canvas, optimally it would be rectangular, encapsulating just the molecule.

here's the original image:

Doing some googling i came across PIL/python code that was reported to work, however in my hands, running the code below over-crops the image.

import Image import sys  image=Image.open('L_2d.png') image.load()  imageSize = image.size imageBox = image.getbbox()  imageComponents = image.split()  rgbImage = Image.new("RGB", imageSize, (0,0,0)) rgbImage.paste(image, mask=imageComponents[3]) croppedBox = rgbImage.getbbox() print imageBox print croppedBox if imageBox != croppedBox:     cropped=image.crop(croppedBox)     print 'L_2d.png:', "Size:", imageSize, "New Size:",croppedBox     cropped.save('L_2d_cropped.png') 

the output is this:

Can anyone more familiar with image-processing/PLI can help me figure out the issue?

Answer 1

Install Pillow

pip install Pillow 

and use as

from PIL import Image      image=Image.open('L_2d.png')  imageBox = image.getbbox() cropped = image.crop(imageBox) cropped.save('L_2d_cropped.png') 

When you search for boundaries by mask=imageComponents[3], you search only by blue channel.