""" This is a program to dither an image using Minimized Average Error dithering, as opposed to the Floyd-Steinberg dithering method, which most programs (including PIL/Pillow) use to dither quantized images References: en.wikipedia.org/wiki/Floyd-Steinberg_dithering good pseudocode en.wikipedia.org/wiki/Error_diffusion MAE dithering distribution matrix https://www.geeksforgeeks.org/python-channel-drop-using-pillow Name's on the tin Tested on Windows and Linux """ # INF360 - Programming in Python # Levi Smith # Final Project import sys # to exit in case of bad fileName try: from PIL import Image # PIL is an image editing library with many pixel-based functions except: print("Pillow is not installed, try: pip install Pillow") sys.exit() import os # for console clear function try: import numpy as np # to easily assign color channels as a single array except: print("numpy is not installed, try: pip install numpy") sys.exit() import logging logging.basicConfig(filename="ditherlog.txt", level=logging.DEBUG, format=' %(asctime)s - %(levelname)s - %(message)s') def findNearestColor(RGB): return round((qStep - 1) * RGB / 255) * (255 / (qStep - 1)) # scales up rgb to be divisible by 255 def singleChannelDither(im): for y in range(im.size[1]): for x in range(im.size[0]): oldPixel = im.getpixel((x, y)) # plucks pixel from original image before it gets changed newPixel = round(findNearestColor(oldPixel)) # gets value for quantized pixel im.putpixel((x, y), newPixel) # places quantized pixel in new image quantError = oldPixel - newPixel # calculates difference to distribute fractions of later for i in currentDitherMatrix: #loops through length of dither matrix, applying x and y offset and dither proportion if (x + i[0] > 0 and x + i[0] < im.size[0] and y + i[1] > 0 and y + i[1] < im.size[1]): #checks if pixels are in bounds of image im.putpixel((x + i[0], y + i[1]), round(im.getpixel((x + i[0], y + i[1])) + (quantError * i[2]))) # line that puts pixels in their place with distribution fraction if y % round(im.size[1] / 4) == 0: print(f"{round((y / im.size[1]) * 100)}%") # structure of "Key" : [[x-offset, y-offset, distributionfraction],...] ditherStyleDict = { "MAE" : [[1, 0, 7.0/48.0], [2, 0, 5.0/48.0], [-2, 1, 3.0/48.0], [-1, 1, 5.0/48.0], [0, 1, 7.0/48.0], [1, 1, 5.0/48.0], [2, 1, 3.0/48.0], [-2, 2, 1.0/48.0], [-1, 2, 3.0/48.0], [0, 2, 5.0/48.0], [1, 2, 3.0/48.0], [2, 2, 1.0/48.0]], "FS" : [[1, 0, 7.0/16.0], [-1, 1, 3.0/16.0], [0, 1, 5.0/16.0], [1, 1, 1.0/16.0]]} currentDitherMatrix = ditherStyleDict["FS"] # default settings for a fast dither currentChannelType = "Grayscale" imageName = "" qStep = 2 def mainMenu(): print("Main menu:") print(" 1. Generate Image") print(" 2. Settings") print(" 3. Exit") print("Choose which option you would like") choice = input(">> ") os.system('clear') if choice == "1": generateImage() elif choice == "2": settingsMenu() elif choice == "3": print("Goodbye") sys.exit() else: print("Invalid input, please try again") logging.warning('Invalid option input: ' + choice) mainMenu() def generateImage(): global imageName print("Input file name, including extension") currentFile = input(">> ") os.system('clear') imageName = currentFile try: currentFile = Image.open("./" + currentFile) if currentChannelType == "Grayscale": grayscaleDither(currentFile) elif currentChannelType == "RGB": rgbDither(currentFile) print("Thank you for using my dithering program, goodbye") except: print("Couldn't open file, is it in the working directory?") mainMenu() sys.exit() def grayscaleDither(currentFile): currentFile = currentFile.convert("L") print("Progress:") singleChannelDither(currentFile) currentFile.save("d" + imageName) def rgbDither(currentFile): redChannel = Image.fromarray(np.array(currentFile, np.uint8)[::, ::, 0])#numpy can pull a list from greenChannel = Image.fromarray(np.array(currentFile, np.uint8)[::, ::, 1])#a multi-dimensional list blueChannel = Image.fromarray(np.array(currentFile, np.uint8)[::, ::, 2])#these lines convert to img print("Channel 1 Progress:") singleChannelDither(redChannel) print("Channel 2 Progress:") singleChannelDither(greenChannel) print("Channel 3 Progress:") singleChannelDither(blueChannel) currentFile = Image.merge("RGB", (redChannel, greenChannel, blueChannel)) #merge from Pillow into one image currentFile.save("d" + imageName) #Menus def settingsMenu(): print("Settings:") print(" 1. Number of output colors") print(" 2. Dithering Style") print(" 3. Color Channels in Output") print(" 4. Go Back") choice = input(">> ") os.system('clear') if choice == "1": outputColorsMenu() elif choice == "2": ditherChoiceMenu() elif choice == "3": grayscaleRGBMenu() elif choice == "4": mainMenu() else: logging.warning('Invalid option input: ' + choice) print("Invalid input") settingsMenu() def outputColorsMenu(): global qStep print("Enter the number of colors to be in the final output, or type 'back' to go back to settings") temp = input(">> ") os.system('clear') try: qStep = int(temp) except: if temp.tolower() == 'back': settingsMenu() else: logging.warning('Invalid qStep input: ' + str(temp)) print("Invalid input") outputColorsMenu() settingsMenu() def ditherChoiceMenu(): global currentDitherMatrix print("Which dithering style would you like to use?") print(" 1. Floyd-Steinberg") print(" 2. Minimized average error") print(" 3. Go Back") choice = input(">> ") os.system('clear') if choice == "1": currentDitherMatrix = ditherStyleDict["FS"] elif choice == "2": currentDitherMatrix = ditherStyleDict["MAE"] elif choice == "3": settingsMenu() else: print("Invalid input") logging.warning('Invalid option input: ' + choice) ditherChoiceMenu() settingsMenu() def grayscaleRGBMenu(): global currentChannelType print("Choose how you would like the output image to look") print(" 1. Grayscale") print(" 2. RGB") print(" 3. Go back") choice = input(">> ") os.system('clear') if choice == "1": currentChannelType = "Grayscale" elif choice == "2": currentChannelType = "RGB" elif choice == "3": settingsMenu() else: print("Invalid input") logging.warning('Invalid option input: ' + choice) grayscaleRGBMenu() settingsMenu() #end of menus logging.debug('Start of program') os.system('clear') print('''Welcome to my dithering program! Tested file types: .png, .jpeg Tested on Linux and Windows ''') mainMenu() logging.debug('End of Program')