Visual hash of a hex number (UUID for eg)

hex.py

from PIL import Image

def value_to_trinary(value):
    trin = ""
    orig = value
    while(value):
        mod = value % 3
        value = value / 3
        trin = str(mod) + trin
    while(len(trin) < 3):
        trin = "0" + trin
    return trin


def to_row(value, width=6, COLOURS=("\x16\x32\xff", "\xff\x16\x00", "\x45\xff\x00")):
    data = ""
    if value == 0:
        return COLOURS[0]*width*3
    else:
        trin = value_to_trinary(value)
        for digit in trin:
            data = data + (COLOURS[int(digit)] * width)
        return data
        

def hex_to_bar(hex_string, width=6):
    data = ""
    for hd in hex_string:
        val = int(hd, 16)
        data = data + to_row(val, width=width)
    return data

def hex_to_image(hex_string, width=6):
    data = hex_to_bar(hex_string)
    i = Image.fromstring("RGB", (width*3, len(data)/(width*9)), data)
    i = i.rotate(90)
    return i

def get_sig_value(sig, SIG_COLOURS=("1","2","0")):
    if sig[0] > sig[1]:
        if sig[0] > sig[2]:
            return SIG_COLOURS[0]
        else:
            return SIG_COLOURS[2]
    elif sig[1] > sig[2]:
        return SIG_COLOURS[1]
    else:
        return SIG_COLOURS[2]

def imagefile_to_hex(image_filename, SIG_COLOURS=("1","2","0")):
    im = Image.open(image_filename)
    return image_to_hex(im, SIG_COLOURS=SIG_COLOURS)

def image_to_hex(im, SIG_COLOURS=("1","2","0")):
    im = im.rotate(-90)
    width, height = im.size
    step = width / 3 
    offset = width / 6
    raw = list(im.getdata())
    cursor_h = 0
    hex_string = ""
    while(cursor_h != height):
        s = get_sig_value(raw[offset])
        s = s+get_sig_value(raw[offset+step]) 
        s = s+get_sig_value(raw[offset+(step*2)]) 
        hex_string = hex_string + hex(int(s,3))[-1]
        cursor_h += 1
        raw = raw[width:]
    return hex_string

def test():
    from uuid import uuid4
    u = uuid4().hex
    print "Encoding %s to 'test.png'" % u
    i = hex_to_image(u)
    i.save("test.png", "PNG")
    print "Attempting to load image and decode"
    hex_str = imagefile_to_hex('test.png')
    print "Got %s from file" % hex_str
    hex_str2 = image_to_hex(i)
    print "Got %s directly" % hex_str2
    print "Should be %s" % u
    assert u == hex_str
    assert u == hex_str2
    

if __name__ == "__main__":
    test()