In Python, using 3rd party Pillow module (pip install pillow) for processing images:

from PIL import Image
import math

def extract_lsbs(data):
    '''Extract LSBs from RGB data as a string of 1s and 0s.
    '''
    s = []
    for r,g,b in data:
        s.extend([str(r & 1), str(g & 1), str(b & 1)])
    return ''.join(s)

def decode00(bits):
    '''Decode Header: [0, 0]
       Next 16-bits: message length in bits
       Followed by the message itself, ASCII characters encoded by groups of 8bit, most-significant bit (MSB) first
       Return the decoded string
    '''
    LENGTH_START = 2
    DATA_START = 18
    if bits[:LENGTH_START] != '00':
        raise ValueError('incorrect header')
    length = int(bits[LENGTH_START:18], 2)
    if length % 8 != 0:  # Assume message length is a multiple of 8 bits given description.
        raise ValueError('length not multiple of 8 bits')
    reqlen = DATA_START + length
    if reqlen > len(bits):  # Sanity check
        raise ValueError('length exceeds data')
    databits = bits[DATA_START:reqlen]
    return int(databits, 2).to_bytes(length // 8).decode()

def decode10(bits):
    '''Decode Header: [1, 0]
       Next 16 bits: image width in pixels
       Next 16 bits: image height in pixels
       Raw pixels of the binary image
       Return the decoded image.
    '''
    WIDTH_START = 2
    HEIGHT_START = 18
    DATA_START = 34
    if bits[:WIDTH_START] != '10':
        raise ValueError('incorrect header')
    width = int(bits[WIDTH_START:HEIGHT_START], 2)
    height = int(bits[HEIGHT_START:DATA_START], 2)
    reqlen = DATA_START + width * height
    if reqlen > len(bits):
        raise ValueError('length exceeds data')
    databits = bits[DATA_START:reqlen]

    # Collect row data
    pad = 8 - width % 8  # Image requires row data to be multiple of 8 bits.
    rowbytes = math.ceil(width / 8)  # Number of bytes needed for a row
    imdata = bytearray()
    for row in range(height):
        rowbits = databits[row * width:(row + 1) * width] + '0' * pad
        imdata.extend(int(rowbits, 2).to_bytes(length=rowbytes))
    return Image.frombytes('1', (width, height), imdata)
        
for filename in ('black.png', 'contrast.png', 'flower.png', 'cat.png'):
    im = Image.open(filename)
    data = im.get_flattened_data()
    print(decode00(extract_lsbs(data)))

im = Image.open('butterfly.png')
data = im.get_flattened_data()
im2 = decode10(extract_lsbs(data))
im2.show()

And the final image contains the quote:

... if two of them are dead.
Benjamin Franklin