Python colorsys 模块，rgb_to_yiq() 实例源码

def background_color(self):
        try:
            hex_color = self.info['background_color']
        except KeyError:
            return TingApp.default_background_color

        try:
            color = _hex_color_to_tuple(hex_color)
        except:
            logging.exception('Failed to parse hex color, using default')
            return TingApp.default_background_color

        # colorsys works with colors between 0 and 1
        fractional_color = _color_multiply(color, 1/255.0)
        y, i, q = colorsys.rgb_to_yiq(*fractional_color)

        if y > 0.6:
            y = 0.6
            fractional_color = colorsys.yiq_to_rgb(y, i, q)
            color = _color_multiply(fractional_color, 255)
            logging.warning(
                'Background color was too bright (white text must be visible on top of this '
                'color), color "%s" was darkened to "%s"' % (hex_color, _tuple_to_hex_color(color)))

        return color

def test_yiq_values(self):
        values = [
            # rgb, yiq
            ((0.0, 0.0, 0.0), (0.0, 0.0, 0.0)), # black
            ((0.0, 0.0, 1.0), (0.11, -0.3217, 0.3121)), # blue
            ((0.0, 1.0, 0.0), (0.59, -0.2773, -0.5251)), # green
            ((0.0, 1.0, 1.0), (0.7, -0.599, -0.213)), # cyan
            ((1.0, 0.0, 0.0), (0.3, 0.599, 0.213)), # red
            ((1.0, 0.0, 1.0), (0.41, 0.2773, 0.5251)), # purple
            ((1.0, 1.0, 0.0), (0.89, 0.3217, -0.3121)), # yellow
            ((1.0, 1.0, 1.0), (1.0, 0.0, 0.0)), # white
            ((0.5, 0.5, 0.5), (0.5, 0.0, 0.0)), # grey
        ]
        for (rgb, yiq) in values:
            self.assertTripleEqual(yiq, colorsys.rgb_to_yiq(*rgb))
            self.assertTripleEqual(rgb, colorsys.yiq_to_rgb(*yiq))

def test_yiq_values(self):
        values = [
            # rgb, yiq
            ((0.0, 0.0, 0.0), (0.0, 0.0, 0.0)), # black
            ((0.0, 0.0, 1.0), (0.11, -0.3217, 0.3121)), # blue
            ((0.0, 1.0, 0.0), (0.59, -0.2773, -0.5251)), # green
            ((0.0, 1.0, 1.0), (0.7, -0.599, -0.213)), # cyan
            ((1.0, 0.0, 0.0), (0.3, 0.599, 0.213)), # red
            ((1.0, 0.0, 1.0), (0.41, 0.2773, 0.5251)), # purple
            ((1.0, 1.0, 0.0), (0.89, 0.3217, -0.3121)), # yellow
            ((1.0, 1.0, 1.0), (1.0, 0.0, 0.0)), # white
            ((0.5, 0.5, 0.5), (0.5, 0.0, 0.0)), # grey
        ]
        for (rgb, yiq) in values:
            self.assertTripleEqual(yiq, colorsys.rgb_to_yiq(*rgb))
            self.assertTripleEqual(rgb, colorsys.yiq_to_rgb(*yiq))

def yiq(self):
        """
        Returns a 3-tuple of (y, i, q) float values; y values can be between
        0.0 and 1.0, whilst i and q values can be between -1.0 and 1.0.
        """
        return colorsys.rgb_to_yiq(self.red, self.green, self.blue)

def test_yiq_roundtrip(self):
        for r in frange(0.0, 1.0, 0.2):
            for g in frange(0.0, 1.0, 0.2):
                for b in frange(0.0, 1.0, 0.2):
                    rgb = (r, g, b)
                    self.assertTripleEqual(
                        rgb,
                        colorsys.yiq_to_rgb(*colorsys.rgb_to_yiq(*rgb))
                    )

def darken_colors(self, data):
        def change_color(color):
            rgb = self._html_color_to_rgb(color)
            if not rgb:
                return color
            yiq = colorsys.rgb_to_yiq(*(x / 255.0 for x in rgb))
            if yiq[0] > self.MIN_Y_TO_DARKEN:
                rgb = self._change_brightness(color, float(1 - (yiq[0] - self.MIN_Y_TO_DARKEN)))
                return self._rgb_to_html_color(*rgb)
            return color

        if 'combined_colors' in data:
            data['combined_colors'] = [change_color(color) for color in data['combined_colors']]

def test_yiq_roundtrip(self):
        for r in frange(0.0, 1.0, 0.2):
            for g in frange(0.0, 1.0, 0.2):
                for b in frange(0.0, 1.0, 0.2):
                    rgb = (r, g, b)
                    self.assertTripleEqual(
                        rgb,
                        colorsys.yiq_to_rgb(*colorsys.rgb_to_yiq(*rgb))
                    )

def RGBToYIQ(red, green, blue):
    return colorsys.rgb_to_yiq(
        float(red) / 0xff, float(green) / 0xff, float(blue) / 0xff)

def get_random_pastel_color(tone=None, black_list: list=None) -> namedtuple:
    """Get a random dark or light color as string, useful for CSS styling."""
    light_colors_tuple = (
        'aliceblue', 'antiquewhite', 'aqua', 'aquamarine', 'azure', 'beige',
        'cornsilk', 'floralwhite', 'ghostwhite', 'grey', 'honeydew', 'ivory',
        'lavender', 'lavenderblush', 'lemonchiffon', 'lightcyan',
        'lightgoldenrodyellow', 'lightgrey', 'lightpink', 'lightskyblue',
        'lightyellow', 'linen', 'mint', 'mintcream', 'oldlace', 'papayawhip',
        'peachpuff', 'seashell', 'skyblue', 'snow', 'thistle', 'white')
    dark_colors_tuple = (
        'brown', 'chocolate', 'crimson', 'darkblue', 'darkgoldenrod',
        'darkgray', 'darkgreen', 'darkolivegreen', 'darkorange', 'darkred',
        'darkslateblue', 'darkslategray', 'dimgray', 'dodgerblue',
        'firebrick', 'forestgreen', 'indigo', 'maroon', 'mediumblue',
        'midnightblue', 'navy', 'olive', 'olivedrab', 'royalblue',
        'saddlebrown', 'seagreen', 'sienna', 'slategray', 'teal')

    if tone.lower() == "light":
        colors_tuple = light_colors_tuple
    elif tone.lower() == "dark":
        colors_tuple = dark_colors_tuple
    else:
        colors_tuple = light_colors_tuple + dark_colors_tuple

    if black_list:
        colors_tuple = tuple(set(colors_tuple).difference(set(black_list)))

    color = choice(colors_tuple)
    hexa = NAMED2HEX[color]
    rgb = hex2rgb(hexa)
    hls = rgb_to_hls(rgb.red, rgb.green, rgb.blue)
    hsv = rgb_to_hsv(rgb.red, rgb.green, rgb.blue)
    yiq = rgb_to_yiq(rgb.red, rgb.green, rgb.blue)

    hls = namedtuple("HLS", "h l s")(  # Round bcause default precision is huge
        round(hls[0], 2), round(hls[1], 2), round(hls[2], 2))
    hsv = namedtuple("HSV", "h s v")(
        round(hsv[0], 2), round(hsv[1], 2), round(hsv[2], 2))
    yiq = namedtuple("YIQ", "y i q")(
        round(yiq[0], 2), round(yiq[1], 2), round(yiq[2], 2))
    per = lambda value: int(value * 100 / 255)  # To Percentage, 0~255 > 0~100%

    return namedtuple("PastelColor", "name hex rgb hls hsv yiq css css_prcnt")(
        color, hexa, rgb, hls, hsv, yiq,
        f"rgb({rgb.red},{rgb.green},{rgb.blue})",  # rgb(int, int, int)
        f"rgb({per(rgb.red)}%,{per(rgb.green)}%,{per(rgb.blue)}%)")  # rgb(%,%)