Converting Hex to RGB value in Python

问题:

Working off Jeremy's response here: Converting hex color to RGB and vice-versa I was able to get a python program to convert preset colour hex codes (example #B4FBB8), however from an end-user perspective we can't ask people to edit code & run from there. How can one prompt the user to enter a hex value and then have it spit out a RGB value from there?

Here's the code I have thus far:

def hex_to_rgb(value):
    value = value.lstrip('#')
    lv = len(value)
    return tuple(int(value[i:i + lv // 3], 16) for i in range(0, lv, lv // 3))


def rgb_to_hex(rgb):
    return '#%02x%02x%02x' % rgb

hex_to_rgb("#ffffff")              # ==> (255, 255, 255)
hex_to_rgb("#ffffffffffff")        # ==> (65535, 65535, 65535)
rgb_to_hex((255, 255, 255))        # ==> '#ffffff'
rgb_to_hex((65535, 65535, 65535))  # ==> '#ffffffffffff'

print('Please enter your colour hex')

hex == input("")

print('Calculating...')
print(hex_to_rgb(hex()))

Using the line print(hex_to_rgb('#B4FBB8')) I'm able to get it to spit out the correct RGB value which is (180, 251, 184)

It's probably super simple - I'm still pretty rough with Python.

回答1:

I believe that this does what you are looking for:

h = input('Enter hex: ').lstrip('#')
print('RGB =', tuple(int(h[i:i+2], 16) for i in (0, 2, 4)))

(The above was written for Python 3)

Sample run:

Enter hex: #B4FBB8
RGB = (180, 251, 184)

Writing to a file

To write to a file with handle fhandle while preserving the formatting:

fhandle.write('RGB = {}'.format( tuple(int(h[i:i+2], 16) for i in (0, 2, 4)) ))

回答2:

A lazy option: webcolors package has a hex_to_rgb function.

回答3:

There are two small errors here!

hex == input("")

Should be:

user_hex = input("")

You want to assign the output of input() to hex, not check for comparison. Also, as mentioned in comments (@koukouviou) don't override hex, instead call it something like user_hex.

Also:

print(hex_to_rgb(hex()))

Should be:

print(hex_to_rgb(user_hex))

You want to use the value of hex, not the type's callable method (__call__).

回答4:

the floats version:

 def hextofloats(h):
    return [int(h[i:i + 2], 16) / 255. for i in (1, 3, 5)] # skip '#'

 def floatstohex(rgb):
    return f'#{int(rgb[0]*255):02x}{int(rgb[1]*255):02x}{int(rgb[2]*255):02x}'

回答5:

All the answers I've seen involve manipulation of a hex string. In my view, I'd prefer to work with encoded integers and RGB triples themselves, not just strings. This has the benefit of not requiring that a color be represented in hexadecimal-- it could be in octal, binary, decimal, what have you.

Converting an RGB triple to an integer is easy.

rgb = (0xc4, 0xfb, 0xa1) # (196, 251, 161)

def rgb2int(r,g,b):
    return (256**2)*r + 256*g + b

c = rgb2int(*rgb) # 12909473
print(hex(c))     # '0xc4fba1'

We need a little more math for the opposite direction. I've lifted the following from my answer to a similar Math exchange question.

c = 0xc4fba1

def int2rgb(n):
    b = n % 256
    g = int( ((n-b)/256) % 256 )      # always an integer
    r = int( ((n-b)/256**2) - g/256 ) # ditto
    return (r,g,b)

print(tuple(map(hex, int2rgb(c)))) # ('0xc4', '0xfb', '0xa1')

With this approach, you can convert to and from strings with ease.