Added dynamic resolution to Photo-to-ASCII

aryanrai2001 · aryanrai2001 · commit eff6ee7221a3 · 2023-06-24T01:37:31.000+05:30
diff --git a/Photo To Ascii/photo_to_ascii.py b/Photo To Ascii/photo_to_ascii.py
@@ -1,11 +1,49 @@
+'''
+Script that converts any Image into its ASCII representation.
+'''
+
+from sys import exit as sysexit
 from PIL import Image, ImageEnhance
 
-# ASCII characters used to build the output text
-char_ramp = []
 
-# Choose character sequence for mapping
-def set_char_ramp():
-    global char_ramp
+def pixels_to_ascii(image, char_ramp):
+    '''
+    Function that takes in an image and a character sequence. And returns a string containing 
+    the ASCII representation of the image based on the character sequence provided.
+    '''
+
+    pixels = image.convert("L").getdata()
+    characters = " ".join([char_ramp[int((pixel/256)*len(char_ramp))] for pixel in pixels])
+    pixel_count = len(characters)
+    scanline_width = image.width * 2
+
+    return "\n".join([characters[index:(index+scanline_width)]
+            for index in range(0, pixel_count, scanline_width)])
+
+
+def input_image():
+    '''
+    Function that asks user for a path to an image file and checks for validity.
+    Then it loads and returns the image and the path as a tuple(image, path).
+    '''
+
+    path = input("Enter a valid pathname to an image:\n")
+
+    try:
+        image = Image.open(path)
+    except IOError:
+        print("Invalid Path!")
+        sysexit()
+
+    return image, path
+
+
+def input_ramp():
+    '''
+    Function that asks the user to choose from a set of character sequences
+    or to specify their own custom sequence and then returns that as a string.
+    '''
+
     print("Choose a Character Sequence!")
     print("1 - Basic")
     print("2 - Standard (Short)")
@@ -17,90 +55,123 @@ def set_char_ramp():
 
     try:
         choice = int(choice)
-    except Exception:
+    except ValueError:
         print("Invalid Input!")
-        exit()
+        sysexit()
 
     if choice == 1:
-        char_ramp = list("00011111...")
-    elif choice == 2:
-        char_ramp = list("@%#*+=-:. ")
-    elif choice == 3:
-        char_ramp = list("$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/\\|()1}{[]?-_+~<>i!lI;:,\"^`'. ")
-    elif choice == 4:
-        char_ramp = ["█", "▉", "▊", "▋", "▌", "▍", "▎", "▏"]
-    elif choice == 5:
-        char_ramp = ["█", "▓", "▒", "░", " "]
-    elif choice == 6:
+        return list("00011111...")
+    if choice == 2:
+        return list("@%#*+=-:. ")
+    if choice == 3:
+        return list("$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/\\|()1}{[]?-_+~<>i!lI;:,\"^`'. ")
+    if choice == 4:
+        return ["█", "▉", "▊", "▋", "▌", "▍", "▎", "▏"]
+    if choice == 5:
+        return ["█", "▓", "▒", "░", " "]
+    if choice == 6:
         custom_ramp = input("Enter your Character Sequence from High density to Low: ")
         if len(custom_ramp) == 0:
             print("Invalid Input!")
-            exit()
-        char_ramp = list(custom_ramp)
-    else:
-        print("Invalid Input!")
-        exit()
+            sysexit()
+        return list(custom_ramp)
 
+    print("Invalid Input!")
+    sysexit()
 
-# Convert pixels to a string of ASCII characters
-def pixels_to_ascii(image, contrast_factor):
-    image = image.convert("L")
-    enhancer = ImageEnhance.Contrast(image)
-    image = enhancer.enhance(contrast_factor)
-    pixels = image.getdata()
-    characters = " ".join([char_ramp[int((pixel/256)*len(char_ramp))] for pixel in pixels])
-    return(characters)
 
-# Driver function
-def photoascii():
-    # Attempt to open image file from user-input
-    path = input("Enter a valid pathname to an image:\n")
-    try:
-        image = Image.open(path)
-    except Exception:
-        print("Invalid Path!")
-        exit()
-    
-    contrast_factor = input("Enter contrast factor (1 = Original Contrast) [Note: Enter negative value to invert output] : ")
+def input_contrast():
+    '''
+    Function that asks user for the contrast factor that is to be applied
+    on the image before conversion. And returns it.
+    '''
+
+    while True:
+        contrast_factor = input("Enter contrast factor [Default - 1 | '?' for info] : ")
+        if contrast_factor == '?':
+            print("Contrast factor is a value that is used to controle the contrast of the output.",
+                "Default value of the contrast factor is 1.",
+                "Entering a negative value will invert the output.")
+        else:
+            break
+
     try:
         contrast_factor = float(contrast_factor)
-    except Exception:
+    except ValueError:
         print("Invalid Input!")
-        exit()
-    
-    set_char_ramp()
-    
-    if contrast_factor < 0:
-        global char_ramp
-        char_ramp.reverse()
-        contrast_factor = -contrast_factor
-    
-    # Fetch the name of the image file
+        sysexit()
+
+    return contrast_factor
+
+
+def resize_image(image):
+    '''
+    Function that takes in an image and asks the user for a sample size.
+    Then returns a resized image such that each pixel represents the sample grid.
+    '''
+
+    while True:
+        sample_size = input("Enter the sample size [Default - 4 | '?' for info] : ")
+        if sample_size == '?':
+            print("Sample size refers to the number of pixels",
+                "that will be sampled for one character.",
+                "Default value of sample size is 4.",
+                "Its value must be greater than or equal to 1.")
+        else:
+            break
+
+    try:
+        sample_size = int(sample_size)
+    except ValueError:
+        print("Invalid Input!")
+        sysexit()
+
+    if sample_size <= 0:
+        print("Invalid Input!")
+        sysexit()
+
+    width, height = image.size
+    new_width = width // sample_size
+    new_height = (new_width * height) // width
+
+    return image.resize((new_width, new_height))
+
+
+def get_output_path(path):
+    '''
+    Function that takes in the path of the input image file and returns the
+    path of a text file that the ouput will be saved to. 
+    '''
+
     dot_index = path.rfind('.')
     slash_index = path.rfind('\\')
+
     if slash_index == -1:
         slash_index = path.rfind('/')
+
     image_name = path[slash_index+1:dot_index] + "_" + path[dot_index+1:]
-    
-    # Resize image
-    new_width = 100
-    width, height = image.size
-    ratio = height/width
-    new_height = int(new_width * ratio)
-    resized_image = image.resize((new_width, new_height))
-    
-    # Convert image to ASCII
-    new_image_data = pixels_to_ascii(resized_image, contrast_factor)
-    pixel_count = len(new_image_data)
-    scanline_width = new_width * 2;
-    ascii_image = "\n".join([new_image_data[index:(index+scanline_width)]
-                            for index in range(0, pixel_count, scanline_width)])
-    
-    # Save result to text file
-    with open(path[:slash_index] + "/{}_ASCII.txt".format(image_name), "w", encoding='utf8') as f:
-        f.write(ascii_image)
-
-
-# Run Program
+
+    return path[:slash_index] + f"/{image_name}_ASCII.txt"
+
+
+def main():
+    '''
+    The main function.
+    '''
+
+    image, path = input_image()
+    char_ramp = input_ramp()
+
+    contrast_factor = input_contrast()
+    if contrast_factor < 0:
+        char_ramp.reverse()
+        contrast_factor = -contrast_factor
+
+    image = resize_image(ImageEnhance.Contrast(image).enhance(contrast_factor))
+    ascii_image = pixels_to_ascii(image, char_ramp)
+
+    with open(get_output_path(path), "w", encoding='utf8') as file:
+        file.write(ascii_image)
+
 if __name__ == '__main__':
-    photoascii()
+    main()
