<p>我用两种方法实现了Python图像库图像平均RGB值的计算:</p>
<h2>1-使用列表</h2>
<pre><code>def getAverageRGB(image):
"""
Given PIL Image, return average value of color as (r, g, b)
"""
# no. of pixels in image
npixels = image.size[0]*image.size[1]
# get colors as [(cnt1, (r1, g1, b1)), ...]
cols = image.getcolors(npixels)
# get [(c1*r1, c1*g1, c1*g2),...]
sumRGB = [(x[0]*x[1][0], x[0]*x[1][1], x[0]*x[1][2]) for x in cols]
# calculate (sum(ci*ri)/np, sum(ci*gi)/np, sum(ci*bi)/np)
# the zip gives us [(c1*r1, c2*r2, ..), (c1*g1, c1*g2,...)...]
avg = tuple([sum(x)/npixels for x in zip(*sumRGB)])
return avg
</code></pre>
<h2>2-使用numpy</h2>
^{pr2}$
<p>我很惊讶地发现1比2快20%。在</p>
<p>我正确地使用了numpy吗?有没有更好的方法来实现平均计算?在</p>
<p>在PIL或Pillow中,在Python 3.4+中:</p>
<pre><code>from statistics import mean
average_color = [mean(image.getdata(band)) for band in range(3)]
</code></pre>