Crop white space around figure

crop_white_space_around_figure.py

# references
# https://www.programmersought.com/article/8966116355/
# https://stackoverflow.com/questions/59758904/check-if-image-is-all-white-pixels-with-opencv

# figures in this paper were all cropped using this code snippet - https://arxiv.org/pdf/2101.03300.pdf

# usage - save this code snippet as a python file and use two arguments
# $ python this_program.py </path/to/original/figure> </path/to/output/directory>

# example
# $ python this_program.py /Users/foo/bar/figures/the_figure.png /Users/foo/bar/cropped_figures

# NOTE
# 1. need $ pip install opencv-python
# 2. there is no ending slash / in </path/to/output/directory> !!
# 3. program may take a while to run

import cv2 as io
import sys
import numpy as np

im = io.imread(sys.argv[1])

def corp_margin(img):
	img2=img.sum(axis=2)
	(row,col)=img2.shape
	
	for r in range(0,row):
		if np.mean(img2[r]) != 765:
			row_top=r
			break

	for r in range(row-1,0,-1):
		if np.mean(img2[r]) != 765:
			raw_down=r
			break
	
	# if want to save bottom padding, uncomment the following line
	# raw_down = row - 1

	for c in range(0,col):
		if img2.sum(axis=0)[c]/row != 765:
			col_top=c
			break

	for c in range(col-1,0,-1):
		if img2.sum(axis=0)[c]/row != 765:
			col_down=c
			break

	new_img=img[row_top:raw_down+1,col_top:col_down+1,0:3]
	return new_img

img_re = corp_margin(im)
io.imwrite(f"{sys.argv[2]}/{sys.argv[1].split('/')[-1]}",img_re)

# io.imshow(img_re)