一个小的改进，但使用screencapture 的 TIFF 压缩选项会快一些：
$ time screencapture -t png /tmp/test.png
real 0m0.235s
user 0m0.191s
sys 0m0.016s
$ time screencapture -t tiff /tmp/test.tiff
real 0m0.079s
user 0m0.028s
sys 0m0.026s
正如您所说，这确实有很多开销（子进程创建、从磁盘写入/读取、压缩/解压缩）。
相反，您可以使用 PyObjC 通过 CGWindowListCreateImage 捕获屏幕。我发现捕获一个 1680x1050 像素的屏幕大约需要 70 毫秒（~14fps），并且可以在内存中访问这些值
一些随机笔记：
- 导入
Quartz.CoreGraphics模块是最慢的部分，大约1秒。导入大多数 PyObjC 模块也是如此。在这种情况下不太重要，但对于短暂的进程，您可能最好在 ObjC 中编写工具
- 指定较小的区域会更快一些，但不会很大（对于 100x100 像素的块约为 40 毫秒，对于 1680x1050 的块约为 70 毫秒）。大部分时间似乎都花在了
CGDataProviderCopyData 调用上——我想知道是否有办法直接访问数据，因为我们不需要修改它？
-
ScreenPixel.pixel 函数非常快，但访问大量像素仍然很慢（因为0.01ms * 1650*1050 大约需要 17 秒） - 如果您需要访问大量像素，可能更快 struct.unpack_from 他们全部一口气。
代码如下：
import time
import struct
import Quartz.CoreGraphics as CG
class ScreenPixel(object):
"""Captures the screen using CoreGraphics, and provides access to
the pixel values.
"""
def capture(self, region = None):
"""region should be a CGRect, something like:
>>> import Quartz.CoreGraphics as CG
>>> region = CG.CGRectMake(0, 0, 100, 100)
>>> sp = ScreenPixel()
>>> sp.capture(region=region)
The default region is CG.CGRectInfinite (captures the full screen)
"""
if region is None:
region = CG.CGRectInfinite
else:
# TODO: Odd widths cause the image to warp. This is likely
# caused by offset calculation in ScreenPixel.pixel, and
# could could modified to allow odd-widths
if region.size.width % 2 > 0:
emsg = "Capture region width should be even (was %s)" % (
region.size.width)
raise ValueError(emsg)
# Create screenshot as CGImage
image = CG.CGWindowListCreateImage(
region,
CG.kCGWindowListOptionOnScreenOnly,
CG.kCGNullWindowID,
CG.kCGWindowImageDefault)
# Intermediate step, get pixel data as CGDataProvider
prov = CG.CGImageGetDataProvider(image)
# Copy data out of CGDataProvider, becomes string of bytes
self._data = CG.CGDataProviderCopyData(prov)
# Get width/height of image
self.width = CG.CGImageGetWidth(image)
self.height = CG.CGImageGetHeight(image)
def pixel(self, x, y):
"""Get pixel value at given (x,y) screen coordinates
Must call capture first.
"""
# Pixel data is unsigned char (8bit unsigned integer),
# and there are for (blue,green,red,alpha)
data_format = "BBBB"
# Calculate offset, based on
# http://www.markj.net/iphone-uiimage-pixel-color/
offset = 4 * ((self.width*int(round(y))) + int(round(x)))
# Unpack data from string into Python'y integers
b, g, r, a = struct.unpack_from(data_format, self._data, offset=offset)
# Return BGRA as RGBA
return (r, g, b, a)
if __name__ == '__main__':
# Timer helper-function
import contextlib
@contextlib.contextmanager
def timer(msg):
start = time.time()
yield
end = time.time()
print "%s: %.02fms" % (msg, (end-start)*1000)
# Example usage
sp = ScreenPixel()
with timer("Capture"):
# Take screenshot (takes about 70ms for me)
sp.capture()
with timer("Query"):
# Get pixel value (takes about 0.01ms)
print sp.width, sp.height
print sp.pixel(0, 0)
# To verify screen-cap code is correct, save all pixels to PNG,
# using http://the.taoofmac.com/space/projects/PNGCanvas
from pngcanvas import PNGCanvas
c = PNGCanvas(sp.width, sp.height)
for x in range(sp.width):
for y in range(sp.height):
c.point(x, y, color = sp.pixel(x, y))
with open("test.png", "wb") as f:
f.write(c.dump())