Transform an image to a bitmap

Question

I'm trying to create like a bitmap for an image of a letter but I'm not having the desired result. It's been a few days that I started working with images. I tried to read the image, create a numpy array of it and save the content in a file. I wrote the code bellow:

import numpy as np
from skimage import io
from skimage.transform import resize

image = io.imread(image_path, as_grey=True)
image = resize(image, (28, 28), mode='nearest')
array = np.array(image)
np.savetxt("file.txt", array, fmt="%d")

I'm trying to use images like in this link bellow:

Letter "e"

I was trying to create an array of 0's and 1's. Where the 0's represent the white pixels and the 1's represent the black pixels. Then when I save the result in a file I can see the letter format.

Can anyone guide me on how to get this result?

Thank you.

Answer 1

Check this one out:

from PIL import Image
import numpy as np

img = Image.open('road.jpg')
ary = np.array(img)

# Split the three channels
r,g,b = np.split(ary,3,axis=2)
r=r.reshape(-1)
g=r.reshape(-1)
b=r.reshape(-1)

# Standard RGB to grayscale 
bitmap = list(map(lambda x: 0.299*x[0]+0.587*x[1]+0.114*x[2], 
zip(r,g,b)))
bitmap = np.array(bitmap).reshape([ary.shape[0], ary.shape[1]])
bitmap = np.dot((bitmap > 128).astype(float),255)
im = Image.fromarray(bitmap.astype(np.uint8))
im.save('road.bmp')

The program takes an rgb image and converts it in a numpy array. It then splits it in 3 vectors, one for each channel. I uses the color vectors to create a gray vector. After that it comperes elements with 128, if lower than writes 0(black) else is 255. Next step is reshape and save.

Answer 2

You can use pillow

from PIL import Image

img = Image.open("haha.jpg")
img = img.tobitmap()

Answer 3

It takes three steps to do it. First convert original image to a list of pixels. Second change every pixel to either black(0,0,0) or white(255,255,255). Third convert the list back to image and save it.

code:

from PIL import Image

threshold = 10

# convert image to a list of pixels
img = Image.open('letter.jpg')
pixels = list(img.getdata())

# convert data list to contain only black or white
newPixels = []
for pixel in pixels:
    # if looks like black, convert to black
    if pixel[0] <= threshold:
        newPixel = (0, 0, 0)
    # if looks like white, convert to white
    else:
        newPixel = (255, 255, 255)
    newPixels.append(newPixel)

# create a image and put data into it
newImg = Image.new(img.mode, img.size)
newImg.putdata(newPixels)
newImg.save('new-letter.jpg')

threshold is what decides a pixel being black or white, as you can see it the code. Threshold of 50 looks like this , threshold of 30 looks like this , threshold of 10 looks like this , if you tune it down to 5, the output starts to lose pixels: .