将整数转换为RGB值,然后使用Python返回 [英] convert Integers to RGB values and back with Python
问题描述
我有两个函数,一个函数从给定的Integer返回RGB值,另一个函数进行相反的操作,为它提供RGB值,它返回一个Integer。我通过查看是否将转换为RGB的整数从RGB转换回原始整数值来对此进行测试,但是我得到了不同的值。
I have two functions, one to return RGB values from a given Integer, and the other function does the reverse, providing it with RGB values it returns an Integer. I'm testing this by seeing if the integer i convert to RGB turns back from RGB into the original integer value, but I'm getting different values.
def getRGBfromI(RGBint):
blue = RGBint & 255
green = (RGBint >> 8) & 255
red = (RGBint >> 16) & 255
return red, green, blue
def getIfromRGB(rgb):
red = rgb[0]
green = rgb[1]
blue = rgb[2]
print red, green, blue
RGBint = (red<<16) + (green<<8) + blue
return RGBint
测试:
i1 = 2147483647
colr1 = getRGBfromI(i1)
print colr1 # returns (255,255,255)
i2 =getIfromRGB(colr1)
print i1, i2 # returns 2147483647 16777215
在我看来,getRGBfromI()是正确的,而getIfromRGB()是是错误的,但我对此也可能是错误的。
To me it seems like the getRGBfromI() is correct and the getIfromRGB() is incorrect, but I may be wrong about that too.
推荐答案
两个函数似乎都可以正常工作。
Both functions seem to be working fine.
最大由24位整数表示的值(立即忘记符号)是
The max value expressed by a 24 bit integer (forget the sign for now) is
mx = pow(2,24)-1 # i.e. 16777215
所以
i1 = 2147483647
高于 mx
和
colr1 = getRGBfromI(i1)
正确给出
(255, 255, 255) # better to view it in hex as 0xFFFFFF
因为它切掉了高于24的位(0xFFFFFF占用了0到23)
since it cuts out the bits higher than 24 (0xFFFFFF occupies bits from 0 to 23)
Viceversa,
Viceversa,
i2 = getIfromRGB(colr1)
正确给出
16777215
这是您可以用24位表示的最大值(即 mx
)。
which is the max value you can represent with 24 bits (i.e. the mx
above).
如果您倒了在1升的瓶子中装满1.4升水,溢流中会损失一些水。
清空瓶子时,您会发现最大容量为1L
If you pour 1.4 litres of water in a 1L bottle, some water will be lost in the overflow. When you empty the bottle, you will find 1L at max
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