ImageColor Module

doc:http://pillow.readthedocs.io/en/4.1.x/reference/ImageColor.html, http://effbot.org/imagingbook/imagecolor.htm

Normally, you don’t have to use this module explicitly. For example, these are identical:

from PIL import Image
img = Image.new("RGB", (32, 32), "lightgrey")
from PIL import Image, ImageColor
img = Image.new("RGB", (32, 32), ImageColor.getrgb("lightgrey"))
from PIL import Image
img = Image.new("RGB", (32, 32), "#add8e6")
from PIL import Image, ImageColor
img = Image.new("RGB", (32, 32), ImageColor.getrgb("#add8e6"))
from PIL import Image, ImageColor
img = Image.new("RGB", (32, 32), "rgb(173, 216, 230)")
from PIL import Image, ImageColor
img = Image.new("RGB", (32, 32), ImageColor.getrgb("rgb(173, 216, 230)"))

Of course if you have a rgb tuple itself (or an integer for grayscale), you can use it and it doesn’t spend any extra cost:

from PIL import Image
img = Image.new("RGB", (32, 32), (173, 216, 230))
from PIL import Image
img = Image.new("L", (32, 32), 255)

but you can not always so, for example when the color value comes from external or you have any reason to use HSL(, etc). Wherever the color value is needed, you can use the string formats supported by ImageColor module:

  • Hexadecimal color specifiers, given as #rgb or #rrggbb.

    from PIL import Image, ImageDraw
    img = Image.new("RGB", (32, 32))
    dctx = ImageDraw.Draw(img)
    dctx.rectangle((8, 8, 16, 16), fill="#ddddff")
    
  • RGB functions, given as rgb(red, green, blue) where the color values are integers in the range 0 to 255.

    from PIL import Image, ImageDraw
    img = Image.new("RGB", (32, 32))
    dctx = ImageDraw.Draw(img)
    dctx.ellipse((8, 8, 16, 16), fill="rgb(255, 128, 255)")
    

    Alternatively, the color values can be given as three percentages (0% to 100%).

    from PIL import Image, ImageDraw
    img = Image.new("RGB", (32, 32))
    dctx = ImageDraw.Draw(img)
    dctx.ellipse((8, 8, 16, 16), outline="rgb(10%, 100%, 50%)")
    
  • Hue-Saturation-Lightness (HSL) functions, given as hsl(hue, saturation%, lightness%) where hue is the color given as an angle between 0 and 360 (red=0, green=120, blue=240), saturation is a value between 0% and 100% (gray=0%, full color=100%), and lightness is a value between 0% and 100% (black=0%, normal=50%, white=100%).

    from PIL import Image, ImageDraw
    img = Image.new("RGB", (32, 32))
    dctx = ImageDraw.Draw(img)
    dctx.ellipse((8, 8, 16, 16), fill="hsl(0, 100%, 50%)")  # pure red
    
  • Common HTML color names.

    from PIL import Image
    img = Image.new("RGB", (32, 32), "skyblue")
    

ImageColor module has no support for YIQ and HSV, but note that you can use colorsys module of standard library:

import colorsys
from PIL import Image
clr = tuple(map(lambda c: int(c * 255), colorsys.yiq_to_rgb(0.65, 0.3, 0.1)))
img = Image.new("RGB", (32, 32), clr)

getrgb, getcolor, colormap

>>> from PIL import ImageColor
>>>
>>> ImageColor.getrgb("orange")
(255, 165, 0)
>>> ImageColor.getcolor("orange", "RGB")
(255, 165, 0)
>>> ImageColor.getcolor("orange", "RGBA")
(255, 165, 0, 255)
>>> ImageColor.getcolor("orange", "L")
173
>>> len(ImageColor.colormap)
148
>>> list(sorted(ImageColor.colormap.items()))[:2]
[('aliceblue', '#f0f8ff'), ('antiquewhite', '#faebd7')]
import colorsys
from PIL import ImageColor

colors = [
    (n, c,
     ImageColor.getcolor(c, "L"),  # as gray scale
     colorsys.rgb_to_hls(
            *map(lambda _: _ / 255., ImageColor.getrgb(c))  # as (r, g, b) floats
             )  # => HLS
     )
    for n, c in ImageColor.colormap.items()]

s2c = sorted(colors, key=lambda _: _[1])  # order by (r, g, b)
s3c = sorted(colors, key=lambda _: _[2])  # order by grayscale value
s4c = sorted(colors, key=lambda _: _[3])  # order by (hue, lum, sat)
s5c = sorted(colors, key=lambda _: (_[3][2], _[3][1], _[3][0]))  # order by (sat, lum, hue)

print("<html><body>")
print("""
<table border=1>
<thead>
<tr>
<th colspan=2>order by (r, g, b)</th>
<th colspan=2>order by grayscale</th>
<th colspan=2>order by (hue, lum, sat)</th>
<th colspan=2>order by (sat, lum, hue)</th>
</tr>
</thead>
""")
for c2, c3, c4, c5 in zip(s2c, s3c, s4c, s5c):
    print("""\
<tr>
<td>{}</td><td width='50pt' style='background-color: {}'>&nbsp;</td>
<td>{}</td><td width='50pt' style='background-color: {}'>&nbsp;</td>
<td>{}</td><td width='50pt' style='background-color: {}'>&nbsp;</td>
<td>{}</td><td width='50pt' style='background-color: {}'>&nbsp;</td>
</tr>
""".format(c2[0], c2[1], c3[0], c3[1], c4[0], c4[1], c5[0], c5[1]))
print("</table>")
print("</body></html>")