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Nicer range for value histogram of integer images.

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When an ImageItem's data has an integer dtype, this patch ensures that
each bin of the LUT histogram contains the same number of integer
values, in order to avoid "spikes" in the histogram that are merely due
to some bins covering more integer values than others.

This commit needs testing (it was rebased from an old commit).
This commit is contained in:
Antony Lee 2013-12-25 22:03:01 -08:00
parent 33e4a9e213
commit 20b9d079ce
1 changed files with 11 additions and 1 deletions
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12
pyqtgraph/graphicsItems/ImageItem.py
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@ -1,3 +1,5 @@
from __future__ import division
from ..Qt import QtGui, QtCore from ..Qt import QtGui, QtCore
import numpy as np import numpy as np
import collections import collections
@ -295,7 +297,15 @@ class ImageItem(GraphicsObject):
if self.image is None: if self.image is None:
return None,None return None,None
stepData = self.image[::step, ::step] stepData = self.image[::step, ::step]
hist = np.histogram(stepData, bins=bins) if not np.iterable(bins):
mn = stepData.min()
mx = stepData.max()
if stepData.dtype.kind in "ui": # unsigned or signed int
# we want max - min to be a multiple of nbins
range = mn, mn + np.ceil((mx - mn) / bins) * bins
else:
range = mn, mx
hist = np.histogram(stepData, bins=bins, range=range)
return hist[1][:-1], hist[0] return hist[1][:-1], hist[0]
def setPxMode(self, b): def setPxMode(self, b):