Pillow/docs/reference/ImageStat.rst
2019-03-31 14:36:39 +11:00

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.. py:module:: PIL.ImageStat
.. py:currentmodule:: PIL.ImageStat
:py:mod:`ImageStat` Module
==========================
The :py:mod:`ImageStat` module calculates global statistics for an image, or
for a region of an image.
.. py:class:: PIL.ImageStat.Stat(image_or_list, mask=None)
Calculate statistics for the given image. If a mask is included,
only the regions covered by that mask are included in the
statistics. You can also pass in a previously calculated histogram.
:param image: A PIL image, or a precalculated histogram.
:param mask: An optional mask.
.. py:attribute:: extrema
Min/max values for each band in the image.
.. Note:: This relies on the :py:meth:`~PIL.Image.histogram` method, and simply
returns the low and high bins used. This is correct for images with 8 bits per
channel, but fails for other modes such as ``I`` or ``F``. Instead, use
:py:meth:`~PIL.Image.getextrema` to return per-band extrema for the image.
This is more correct and efficient because, for non-8-bit modes, the histogram
method uses :py:meth:`~PIL.Image.getextrema` to determine the bins used.
.. py:attribute:: count
Total number of pixels for each band in the image.
.. py:attribute:: sum
Sum of all pixels for each band in the image.
.. py:attribute:: sum2
Squared sum of all pixels for each band in the image.
.. py:attribute:: mean
Average (arithmetic mean) pixel level for each band in the image.
.. py:attribute:: median
Median pixel level for each band in the image.
.. py:attribute:: rms
RMS (root-mean-square) for each band in the image.
.. py:attribute:: var
Variance for each band in the image.
.. py:attribute:: stddev
Standard deviation for each band in the image.