How to create images with English alphabets (A-Z, a-z, 0-9) in Python?

Question

I want to prepare a dataset for the recognition of English Alphanumeric characters. I want to train my Deep learning model to recognize the characters. Image size should be 32 * 32 or 28 * 28. And Characters should be scaled with the height and width of the Image. Given below is the expected Output.

Character "A" scaled with the Image

I have tried getsize() but I am not able to scale character with the image size.

from PIL import Image, ImageDraw, ImageFont
import os,glob
import numpy as np
import random

parentPath=r"CaptchaDataset\"


charactersList=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','0','1','2','3','4','5','6','7','8','9']
fontTypes=[]

for font in glob.glob("fonts\*"): # Create Image for every font
    fontTypes.append(os.path.abspath(font))
    
for index,character in enumerate(charactersList):
    
    path=os.path.join(parentPath,character+"_"+str(index))
    os.mkdir(path)
    
    
    for imageCounter in range(len(fontTypes)):
        for repeats in range(3): #Number of Images
            img = Image.new('1', (28, 28), color = 'black')
            fnt = ImageFont.truetype(fontTypes[imageCounter], random.randint(30,50))
            w,h=fnt.getsize(character)
            d = ImageDraw.Draw(img)
            d.text(((28-w)/2-5,((28-h)/2)-5), character, font=fnt, fill=(255),align="center") #TO ALIGN CHARACTER IN CENTER
            img=np.pad(img,pad_width=10, mode='constant', constant_values=0) #Manually added padding
            img=Image.fromarray(img)
            img.save(path+"\"+str(imageCounter)+"_"+str(repeats)+".jpg")

UnExpected Output of Above program. "g" is cropped

user_4926757 · Answer

The solution is simple: Create the image after creating the font.

Instead of creating 28x28 pixels image, and drawing a character that may be larger than the image, create the font, get the size, and create the image according to the font's size.

Create the font, and get the font's size:

 fnt = ImageFont.truetype(fontTypes[imageCounter], random.randint(30, 50))
 w, h = fnt.getsize(character)

Set image size according to font size and create the image:

 img_w, img_h = w + 20, h + 20  # Add 20 pixels padding (assume 10 pixels from each side).
 img = Image.new('L', (img_w, img_h), color='black')  # Replace '1' with 'L' (8-bit pixels, black and white - we fill 255 so we can't use 1 bit per pixel)

Draw the character at the center of the image:

 d.text(((img_w-w)/2, (img_h-h)/2), character, font=fnt, fill=255, align="center") # TO ALIGN CHARACTER IN CENTER

Here is a complete (updated) code:

from PIL import Image, ImageDraw, ImageFont
import os,glob
import numpy as np
import random

parentPath = "CaptchaDataset\"

charactersList=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','0','1','2','3','4','5','6','7','8','9']
fontTypes=[]

for font in glob.glob("fonts\*"): # Create Image for every font
    fontTypes.append(os.path.abspath(font))
    
for index,character in enumerate(charactersList):    
    path = os.path.join(parentPath,character + "_" + str(index))

    if not os.path.exists(path):
        os.mkdir(path)
     
    for imageCounter in range(len(fontTypes)):
        for repeats in range(3): # Number of Images
            #img = Image.new('1', (28, 28), color = 'black')
            fnt = ImageFont.truetype(fontTypes[imageCounter], random.randint(30, 50))
            w, h = fnt.getsize(character)
            img_w, img_h = w + 20, h + 20  # Add 20 pixels padding (assume 10 pixels from each side).
            img = Image.new('L', (img_w, img_h), color='black')  # Replace '1' with 'L' (8-bit pixels, black and white - we fill 255 so we can't use 1 bit per pixel)
            d = ImageDraw.Draw(img)
            d.text(((img_w-w)/2, (img_h-h)/2), character, font=fnt, fill=255, align="center") # TO ALIGN CHARACTER IN CENTER
            #img = np.pad(img, pad_width=10, mode='constant', constant_values=0) #Manually added padding
            #img = Image.fromarray(img)
            img.save(path + "\" + str(imageCounter) + "_" + str(repeats) + ".jpg")

Few sample results:

How to create images with English alphabets (A-Z, a-z, 0-9) in Python?

1 Answers