learnopencv/CharClassification/generate_images.py

import os
import random
import numpy as np
import uuid

PATH_TO_LIGHT_BACKGROUNDS = 'light_backgrounds/'
PATH_TO_DARK_BACKGROUNDS = 'dark_backgrounds/'
PATH_TO_FONT_FILES = 'fonts/'
OUTPUT_DIR = 'output/'
NUM_IMAGES_PER_CLASS = 10

# Get all files from directory
def get_files_from_dir(dirname):
  list_files = (os.listdir(dirname))
  list_files = [dirname + x for x in list_files]
  return list_files


# Random perspective distortion created by randomly moving the for corners of the image.
def get_distort_arg():
  amount = 5
  hundred_minus_amount = 100 - amount
  return '\'0,0 ' + str(np.random.randint(0,amount)) + ',' + str(np.random.randint(0,amount)) + ' 100,0 '  + str(np.random.randint(hundred_minus_amount,100)) + ',' + str(np.random.randint(0,amount)) + ' 0,100 '  + str(np.random.randint(0,amount)) + ',' + str(np.random.randint(hundred_minus_amount,100)) + ' 100,100 '  + str(np.random.randint(hundred_minus_amount,100)) + ',' + str(np.random.randint(hundred_minus_amount,100)) + '\''

# Randomly extracts 32x32 regions of an image and saves it to outdir
def create_random_crops(image_filename, num_crops, out_dir):
  dim = os.popen('convert ' + image_filename + ' -ping -format "%w %h" info:').read()
  dim = dim.split()
  im_width = int(dim[0])
  im_height = int(dim[1])
  
  for i in range(0, num_crops):
    # Randomly select first co-ordinate of square for cropping image
    x = random.randint(0,im_width - 32)
    y = random.randint(0,im_height - 32)
    outfile = uuid.uuid4().hex + '.jpg'
    command = "magick convert "+ image_filename + " -crop 32x32"+"+"+str(x)+"+"+str(y)+" " + os.path.join(out_dir, outfile)
    os.system(str(command))

# Generate crops for all files in file_list and store them in dirname
def generate_crops(file_list, dirname):
  if not os.path.isdir(dirname):
    os.mkdir(dirname)
    for f in file_list:
      create_random_crops(f, 10, dirname)


# List of characters
char_list = []
for i in range(65, 65+26):
  char_list.append(chr(i))

# List of digits
for j in range(48,48+10):
  char_list.append(chr(j))

# List of light font colors
color_light = ['white','lime','gray','yellow','silver','aqua']

# List of light dark colors
color_dark = ['black','green','maroon','blue','purple','red']


# List of light backgrounds
light_backgrounds = get_files_from_dir(PATH_TO_LIGHT_BACKGROUNDS)

# List of dark backgrounds
dark_backgrounds = get_files_from_dir(PATH_TO_DARK_BACKGROUNDS)

# List of font files
list_files_fontt = get_files_from_dir(PATH_TO_FONT_FILES)



light_backgrounds_crops_dir = 'light_backgrounds_crops/'
dark_backgrounds_crops_dir = 'dark_backgrounds_crops/'

generate_crops(light_backgrounds, light_backgrounds_crops_dir)
generate_crops(dark_backgrounds, dark_backgrounds_crops_dir)

# List of all files in the crops directory
light_backgrounds = get_files_from_dir(light_backgrounds_crops_dir)
dark_backgrounds = get_files_from_dir(dark_backgrounds_crops_dir)

# List of all backgrounds
all_backgrounds = [dark_backgrounds, light_backgrounds]


# Sample Command-----  magick convert image.jpg -fill Black -font Courier-Oblique -weight 50 -pointsize 12 -gravity center -blur 0x8 -evaluate Gaussian-noise 1.2  -annotate 0+0 "Some text" output_image

for i in range(0,len(char_list)):
  char = char_list[i]
  char_output_dir = OUTPUT_DIR + str(char) + "/"
	
  if not os.path.exists(char_output_dir):
    os.makedirs(char_output_dir)

  print("Generating data " + char_output_dir)
  

  # Generate synthetic images
  for j in range(0,NUM_IMAGES_PER_CLASS):
    
    # Choose a light or dark background
    path = random.choice(all_backgrounds)
    
    # Choose a file
    list_filernd = random.choice(path)
    
    # Choose a font
    list_rfo = random.choice(list_files_fontt)
    
    # Get random distortion
    distort_arg = get_distort_arg()
    
    # Get random blur amount
    blur = random.randint(0,3)
    
    # Get random noise amount
    noise = random.randint(0,5)
    
    # Add random shifts from the center
    x = str(random.randint(-3,3))
    y = str(random.randint(-3,3))
    
    # Choose light color for dark backgrounds and vice-versa
    if path == all_backgrounds[0] :
      color = random.choice(color_light)
    else:
      color = random.choice(color_dark)

    command =  "magick convert " + str(list_filernd) + " -fill "+str(color)+" -font "+ \
            str(list_rfo) + " -weight 200 -pointsize 24 -distort Perspective "+str(distort_arg)+" "+"-gravity center" + " -blur 0x" + str(blur) \
+ " -evaluate Gaussian-noise " + str(noise) +  " " + " -annotate +" + x + "+" + y + " " +  str(char_list[i]) + " " + char_output_dir + "output_file"+str(i)+str(j)+".jpg"
		
    # Uncomment line below to see what command is executed.
    # print(command)
    os.system(str(command))