Python 将 colorsys RGB 坐标转换为十六进制

Question

根据这个回答，我在Python中生成了一些均匀分布的颜色，代码如下：

>>> import colorsys
>>> num_colors = 22
>>> hsv_tuples = [(x*1.0/num_colors, 0.5, 0.5) for x in range(num_colors)]
>>> rgb_tuples = map(lambda x: colorsys.hsv_to_rgb(*x), hsv_tuples)
>>> rgb_tuples
[(0.5, 0.25, 0.25), (0.5, 0.3181818181818182, 0.25), (0.5, 0.38636363636363635, 0.25), (0.5, 0.45454545454545453, 0.25), (0.4772727272727273, 0.5, 0.25), (0.4090909090909091, 0.5, 0.25), (0.34090909090909094, 0.5, 0.25), (0.2727272727272727, 0.5, 0.25), (0.25, 0.5, 0.2954545454545454), (0.25, 0.5, 0.36363636363636365), (0.25, 0.5, 0.43181818181818177), (0.25, 0.5, 0.5), (0.25, 0.4318181818181819, 0.5), (0.25, 0.36363636363636354, 0.5), (0.25, 0.2954545454545454, 0.5), (0.2727272727272727, 0.25, 0.5), (0.34090909090909083, 0.25, 0.5), (0.40909090909090917, 0.25, 0.5), (0.4772727272727273, 0.25, 0.5), (0.5, 0.25, 0.4545454545454546), (0.5, 0.25, 0.38636363636363646), (0.5, 0.25, 0.3181818181818181)]

那么，怎么把这些RGB元组转换回RGB十六进制字符串，比如#FF00AA呢？这可能是个简单的问题，但我一直找不到答案。

Answer 1

最有效的方法是把以十进制表示的RGB颜色转换成十六进制，也就是HEX格式。

  r = int(input('R: '))
  g = int(input('G: '))
  b = int(input('B: '))
  def rgbToHex(r,g,b):
    rgb = [r,g,b]
    x = ''
    for i in rgb:
      x += format(i,'02x').upper()
    if x[0] == x[1] and x[2] == x[3] and x[4] == x[5]:
      x = x[0] + x[2] + x[4]
    return '#'+x
  print(rgbToHex(r,g,b))

Answer 2

1) 把小数乘以256，然后转成整数。如果结果是256，就减去1。

补充说明：因为有很多人不太明白，所以我解释一下，为什么要乘以256（如果结果是256就减1）。这样做是为了确保每个整数输出都有对应的相同数量的小数值。

2) http://docs.python.org/2/library/string.html?highlight=hexadecimal#format-specification-mini-language

'x' 是十六进制格式。它会把数字以16进制的方式输出，数字9以上的部分用小写字母表示。

用这个格式，然后把字母变成大写，再在前面加一个#符号。

Answer 3

对于每种颜色，先把颜色值乘以256，然后取整，最后以十六进制的形式输出（确保是两位数）。例如：

In [1]: rgb_tuples = [(0.5, 0.25, 0.25), (0.5, 0.3181818181818182, 0.25), (0.5, 0.38636363636363635, 0.25), (0.5, 0.45454545454545453, 0.25), (0.4772727272727273, 0.5, 0.25), (0.4090909090909091, 0.5, 0.25), (0.34090909090909094, 0.5, 0.25), (0.2727272727272727, 0.5, 0.25), (0.25, 0.5, 0.2954545454545454), (0.25, 0.5, 0.36363636363636365), (0.25, 0.5, 0.43181818181818177), (0.25, 0.5, 0.5), (0.25, 0.4318181818181819, 0.5), (0.25, 0.36363636363636354, 0.5), (0.25, 0.2954545454545454, 0.5), (0.2727272727272727, 0.25, 0.5), (0.34090909090909083, 0.25, 0.5), (0.40909090909090917, 0.25, 0.5), (0.4772727272727273, 0.25, 0.5), (0.5, 0.25, 0.4545454545454546), (0.5, 0.25, 0.38636363636363646), (0.5, 0.25, 0.3181818181818181)]

In [2]: for (r,g,b) in rgb_tuples:
   ...:     print '%02x%02x%02x' % (int(r*255), int(g*255), int(b*255))
   ...:     
804040
805140
806240
807440