css - Convert RGB color to English color name, like 'green' with Python

Question

I want to convert a color tuple to a color name, like 'yellow' or 'blue'

>>> im = Image.open("test.jpg")
>>> n, color = max(im.getcolors(im.size[0]*im.size[1]))
>>> print color
(119, 172, 152)

Is there a simple way in python to do this?

Answer 1

It looks like webcolors will allow you to do this:

rgb_to_name(rgb_triplet, spec='css3')

Convert a 3-tuple of integers, suitable for use in an rgb() color triplet, to its corresponding normalized color name, if any such name exists; valid values are html4, css2, css21 and css3, and the default is css3.

Example:

>>> rgb_to_name((0, 0, 0))
'black'

it is vice-versa-able:

>>> name_to_rgb('navy')
(0, 0, 128)

To find the closest colour name:

However webcolors raises an exception if it can't find a match for the requested colour. I've written a little fix that delivers the closest matching name for the requested RGB colour. It matches by Euclidian distance in the RGB space.

import webcolors

def closest_colour(requested_colour):
    min_colours = {}
    for key, name in webcolors.css3_hex_to_names.items():
        r_c, g_c, b_c = webcolors.hex_to_rgb(key)
        rd = (r_c - requested_colour[0]) ** 2
        gd = (g_c - requested_colour[1]) ** 2
        bd = (b_c - requested_colour[2]) ** 2
        min_colours[(rd + gd + bd)] = name
    return min_colours[min(min_colours.keys())]

def get_colour_name(requested_colour):
    try:
        closest_name = actual_name = webcolors.rgb_to_name(requested_colour)
    except ValueError:
        closest_name = closest_colour(requested_colour)
        actual_name = None
    return actual_name, closest_name

requested_colour = (119, 172, 152)
actual_name, closest_name = get_colour_name(requested_colour)

print "Actual colour name:", actual_name, ", closest colour name:", closest_name

Output:

Actual colour name: None , closest colour name: cadetblue