Make 96*96 square crops from bounding boxes of ExDark dataset.

cropExDark.py

# -*- coding: utf-8 -*-
"""
Created on Tue Apr  9 14:33:10 2019

Make 96*96 square crops from bounding boxes of ExDark dataset.

@author: Attila Lengyel
"""

import numpy as np
import os, cv2

inpath = r'C:\Projects\MSc Thesis\data\ExDark - Copy\input'
lblpath = r'C:\Projects\MSc Thesis\data\ExDark - Copy\ExDark_Annno'
outpath = r'C:\Projects\MSc Thesis\data\ExDark - Copy\output'

categories = next(os.walk(inpath))[1]
for cat in categories: # Loop through categories
    catpath = os.path.join(inpath,cat)
    im_files = next(os.walk(catpath))[2]
    for im_file in im_files: # Loop through images in category
        im_path = os.path.join(catpath,im_file)
        lbl_path = os.path.join(lblpath,cat,im_file+'.txt')
        
        # Read label file corresponding to image
        with open(lbl_path, 'r') as lblfile:
            lbls = lblfile.readlines()
        for lbl in lbls:
            im = cv2.imread(im_path,cv2.IMREAD_COLOR)[:,:,::-1] # load image
            lbl = lbl.split()
            
            # Calculate crop coordinates if categories correspond
            if lbl[0].lower() == cat.lower():
                x,y,w,h = list(map(int,lbl[1:5]))
                if w<h:
                    dif = int((h-w)/2)
                    x -= dif
                    w += dif*2
                elif w>h:
                    dif = int((w-h)/2)
                    y -= dif
                    h += dif*2
                
                # Check if crop is not out of bounds
                if x < 0:
                    appim = np.zeros((im.shape[0],dif,3))
                    im = np.hstack((appim,im,appim))
                    x = 0
                if y < 0:
                    appim = np.zeros((dif,im.shape[1],3))
                    im = np.vstack((appim,im,appim))
                    y = 0

                im = im[y:y+h,x:x+w] # Crop image
                
                if (w >= 96 and h >= 96): # Resize image if too large
                    im = cv2.resize(im,(96,96))
                    # Save image (only if large enough)
                    imoutpath = os.path.join(outpath,cat,im_file)
                    print(imoutpath)
                    cv2.imwrite(imoutpath,im[:,:,::-1])