xterm 256 color palette translation

tcolor.py

#!/usr/bin/env python2
import sys

COLORS = [
    ('16',  '000000'),
    ('17',  '00005f'),
    ('18',  '000087'),
    ('19',  '0000af'),
    ('20',  '0000d7'),
    ('21',  '0000ff'),
    ('22',  '005f00'),
    ('23',  '005f5f'),
    ('24',  '005f87'),
    ('25',  '005faf'),
    ('26',  '005fd7'),
    ('27',  '005fff'),
    ('28',  '008700'),
    ('29',  '00875f'),
    ('30',  '008787'),
    ('31',  '0087af'),
    ('32',  '0087d7'),
    ('33',  '0087ff'),
    ('34',  '00af00'),
    ('35',  '00af5f'),
    ('36',  '00af87'),
    ('37',  '00afaf'),
    ('38',  '00afd7'),
    ('39',  '00afff'),
    ('40',  '00d700'),
    ('41',  '00d75f'),
    ('42',  '00d787'),
    ('43',  '00d7af'),
    ('44',  '00d7d7'),
    ('45',  '00d7ff'),
    ('46',  '00ff00'),
    ('47',  '00ff5f'),
    ('48',  '00ff87'),
    ('49',  '00ffaf'),
    ('50',  '00ffd7'),
    ('51',  '00ffff'),
    ('52',  '5f0000'),
    ('53',  '5f005f'),
    ('54',  '5f0087'),
    ('55',  '5f00af'),
    ('56',  '5f00d7'),
    ('57',  '5f00ff'),
    ('58',  '5f5f00'),
    ('59',  '5f5f5f'),
    ('60',  '5f5f87'),
    ('61',  '5f5faf'),
    ('62',  '5f5fd7'),
    ('63',  '5f5fff'),
    ('64',  '5f8700'),
    ('65',  '5f875f'),
    ('66',  '5f8787'),
    ('67',  '5f87af'),
    ('68',  '5f87d7'),
    ('69',  '5f87ff'),
    ('70',  '5faf00'),
    ('71',  '5faf5f'),
    ('72',  '5faf87'),
    ('73',  '5fafaf'),
    ('74',  '5fafd7'),
    ('75',  '5fafff'),
    ('76',  '5fd700'),
    ('77',  '5fd75f'),
    ('78',  '5fd787'),
    ('79',  '5fd7af'),
    ('80',  '5fd7d7'),
    ('81',  '5fd7ff'),
    ('82',  '5fff00'),
    ('83',  '5fff5f'),
    ('84',  '5fff87'),
    ('85',  '5fffaf'),
    ('86',  '5fffd7'),
    ('87',  '5fffff'),
    ('88',  '870000'),
    ('89',  '87005f'),
    ('90',  '870087'),
    ('91',  '8700af'),
    ('92',  '8700d7'),
    ('93',  '8700ff'),
    ('94',  '875f00'),
    ('95',  '875f5f'),
    ('96',  '875f87'),
    ('97',  '875faf'),
    ('98',  '875fd7'),
    ('99',  '875fff'),
    ('100', '878700'),
    ('101', '87875f'),
    ('102', '878787'),
    ('103', '8787af'),
    ('104', '8787d7'),
    ('105', '8787ff'),
    ('106', '87af00'),
    ('107', '87af5f'),
    ('108', '87af87'),
    ('109', '87afaf'),
    ('110', '87afd7'),
    ('111', '87afff'),
    ('112', '87d700'),
    ('113', '87d75f'),
    ('114', '87d787'),
    ('115', '87d7af'),
    ('116', '87d7d7'),
    ('117', '87d7ff'),
    ('118', '87ff00'),
    ('119', '87ff5f'),
    ('120', '87ff87'),
    ('121', '87ffaf'),
    ('122', '87ffd7'),
    ('123', '87ffff'),
    ('124', 'af0000'),
    ('125', 'af005f'),
    ('126', 'af0087'),
    ('127', 'af00af'),
    ('128', 'af00d7'),
    ('129', 'af00ff'),
    ('130', 'af5f00'),
    ('131', 'af5f5f'),
    ('132', 'af5f87'),
    ('133', 'af5faf'),
    ('134', 'af5fd7'),
    ('135', 'af5fff'),
    ('136', 'af8700'),
    ('137', 'af875f'),
    ('138', 'af8787'),
    ('139', 'af87af'),
    ('140', 'af87d7'),
    ('141', 'af87ff'),
    ('142', 'afaf00'),
    ('143', 'afaf5f'),
    ('144', 'afaf87'),
    ('145', 'afafaf'),
    ('146', 'afafd7'),
    ('147', 'afafff'),
    ('148', 'afd700'),
    ('149', 'afd75f'),
    ('150', 'afd787'),
    ('151', 'afd7af'),
    ('152', 'afd7d7'),
    ('153', 'afd7ff'),
    ('154', 'afff00'),
    ('155', 'afff5f'),
    ('156', 'afff87'),
    ('157', 'afffaf'),
    ('158', 'afffd7'),
    ('159', 'afffff'),
    ('160', 'd70000'),
    ('161', 'd7005f'),
    ('162', 'd70087'),
    ('163', 'd700af'),
    ('164', 'd700d7'),
    ('165', 'd700ff'),
    ('166', 'd75f00'),
    ('167', 'd75f5f'),
    ('168', 'd75f87'),
    ('169', 'd75faf'),
    ('170', 'd75fd7'),
    ('171', 'd75fff'),
    ('172', 'd78700'),
    ('173', 'd7875f'),
    ('174', 'd78787'),
    ('175', 'd787af'),
    ('176', 'd787d7'),
    ('177', 'd787ff'),
    ('178', 'd7af00'),
    ('179', 'd7af5f'),
    ('180', 'd7af87'),
    ('181', 'd7afaf'),
    ('182', 'd7afd7'),
    ('183', 'd7afff'),
    ('184', 'd7d700'),
    ('185', 'd7d75f'),
    ('186', 'd7d787'),
    ('187', 'd7d7af'),
    ('188', 'd7d7d7'),
    ('189', 'd7d7ff'),
    ('190', 'd7ff00'),
    ('191', 'd7ff5f'),
    ('192', 'd7ff87'),
    ('193', 'd7ffaf'),
    ('194', 'd7ffd7'),
    ('195', 'd7ffff'),
    ('196', 'ff0000'),
    ('197', 'ff005f'),
    ('198', 'ff0087'),
    ('199', 'ff00af'),
    ('200', 'ff00d7'),
    ('201', 'ff00ff'),
    ('202', 'ff5f00'),
    ('203', 'ff5f5f'),
    ('204', 'ff5f87'),
    ('205', 'ff5faf'),
    ('206', 'ff5fd7'),
    ('207', 'ff5fff'),
    ('208', 'ff8700'),
    ('209', 'ff875f'),
    ('210', 'ff8787'),
    ('211', 'ff87af'),
    ('212', 'ff87d7'),
    ('213', 'ff87ff'),
    ('214', 'ffaf00'),
    ('215', 'ffaf5f'),
    ('216', 'ffaf87'),
    ('217', 'ffafaf'),
    ('218', 'ffafd7'),
    ('219', 'ffafff'),
    ('220', 'ffd700'),
    ('221', 'ffd75f'),
    ('222', 'ffd787'),
    ('223', 'ffd7af'),
    ('224', 'ffd7d7'),
    ('225', 'ffd7ff'),
    ('226', 'ffff00'),
    ('227', 'ffff5f'),
    ('228', 'ffff87'),
    ('229', 'ffffaf'),
    ('230', 'ffffd7'),
    ('231', 'ffffff'),

    # Gray-scale range.
    ('232', '080808'),
    ('233', '121212'),
    ('234', '1c1c1c'),
    ('235', '262626'),
    ('236', '303030'),
    ('237', '3a3a3a'),
    ('238', '444444'),
    ('239', '4e4e4e'),
    ('240', '585858'),
    ('241', '626262'),
    ('242', '6c6c6c'),
    ('243', '767676'),
    ('244', '808080'),
    ('245', '8a8a8a'),
    ('246', '949494'),
    ('247', '9e9e9e'),
    ('248', 'a8a8a8'),
    ('249', 'b2b2b2'),
    ('250', 'bcbcbc'),
    ('251', 'c6c6c6'),
    ('252', 'd0d0d0'),
    ('253', 'dadada'),
    ('254', 'e4e4e4'),
    ('255', 'eeeeee'),
]


def get_parts(c):
    return tuple(int(r, 16) for r in [c[:2], c[2:4], c[4:]])


def dumb(a, b):
    return (a[0] - b[0])**2 + (a[1] - b[1])**2 + (a[2] - b[2])**2


def rgb2xyz((r, g, b)):
    r /= 255.0
    g /= 255.0
    b /= 255.0

    r = (((r + 0.055) / 1.055) ** 2.4) if r > 0.04045 else r / 12.92
    g = (((g + 0.055) / 1.055) ** 2.4) if g > 0.04045 else g / 12.92
    b = (((b + 0.055) / 1.055) ** 2.4) if b > 0.04045 else b / 12.92

    x = r * 0.4124 + g * 0.3576 + b * 0.1805
    y = r * 0.2126 + g * 0.7152 + b * 0.0722
    z = r * 0.0193 + g * 0.1192 + b * 0.9505

    return x, y, z


def xyz2lab((x, y, z)):
    x /= 95.047
    y /= 100.000
    z /= 108.883

    x = (x ** (1/3.0)) if x > 0.008856 else 7.787*x + 16/116.0
    y = (y ** (1/3.0)) if y > 0.008856 else 7.787*y + 16/116.0
    z = (z ** (1/3.0)) if z > 0.008856 else 7.787*z + 16/116.0

    return 116*y - 16, 500 * (x - y), 200 * (y - z)


def CIE76(a, b):
    return dumb(xyz2lab(rgb2xyz(a)), xyz2lab(rgb2xyz(b)))


PARTED_COLORS = [(get_parts(c), idx, c) for idx, c in COLORS]
def find_nearest(c, metric=dumb):
    cparts = get_parts(c)
    return min(PARTED_COLORS, key=lambda r: metric(r[0], cparts))


if __name__ == '__main__':
    print '{1} {2}'.format(*find_nearest(sys.argv[1], CIE76))