From 6f24eda48a58680afa14d6035c116b6e0ef7fbc2 Mon Sep 17 00:00:00 2001 From: Hugo Date: Sun, 17 Feb 2019 15:06:29 +0200 Subject: [PATCH] Document format limitations of ImageStat.Stat.extrema and recommend more efficient Image.getextrema --- docs/reference/ImageStat.rst | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/docs/reference/ImageStat.rst b/docs/reference/ImageStat.rst index b8925bf8c..7981cb9e5 100644 --- a/docs/reference/ImageStat.rst +++ b/docs/reference/ImageStat.rst @@ -20,6 +20,14 @@ for a region of an image. 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 :py:meth:`~PIL.Image.getextrema` is + used by the histogram method for non-8-bit modes to return extrema to define the + bins used in the histogram. + .. py:attribute:: count Total number of pixels for each band in the image.