Source code for pyqtgraph.graphicsItems.HistogramLUTItem

GraphicsWidget displaying an image histogram along with gradient editor. Can be used to
adjust the appearance of images.

import weakref

import numpy as np

from .. import debug as debug
from .. import functions as fn
from ..Point import Point
from ..Qt import QtCore, QtGui, QtWidgets
from .AxisItem import *
from .GradientEditorItem import *
from .GraphicsWidget import GraphicsWidget
from .LinearRegionItem import *
from .PlotCurveItem import *
from .ViewBox import *

__all__ = ['HistogramLUTItem']

[docs]class HistogramLUTItem(GraphicsWidget): """ :class:`~pyqtgraph.GraphicsWidget` with controls for adjusting the display of an :class:`~pyqtgraph.ImageItem`. Includes: - Image histogram - Movable region over the histogram to select black/white levels - Gradient editor to define color lookup table for single-channel images Parameters ---------- image : pyqtgraph.ImageItem, optional If provided, control will be automatically linked to the image and changes to the control will be reflected in the image's appearance. This may also be set via :meth:`setImageItem`. fillHistogram : bool, optional By default, the histogram is rendered with a fill. Performance may be improved by disabling the fill. Additional control over the fill is provided by :meth:`fillHistogram`. levelMode : str, optional 'mono' (default) One histogram with a :class:`~pyqtgraph.LinearRegionItem` is displayed to control the black/white levels of the image. This option may be used for color images, in which case the histogram and levels correspond to all channels of the image. 'rgba' A histogram and level control pair is provided for each image channel. The alpha channel histogram and level control are only shown if the image contains an alpha channel. gradientPosition : str, optional Position of the gradient editor relative to the histogram. Must be one of {'right', 'left', 'top', 'bottom'}. 'right' and 'left' options should be used with a 'vertical' orientation; 'top' and 'bottom' options are for 'horizontal' orientation. orientation : str, optional The orientation of the axis along which the histogram is displayed. Either 'vertical' (default) or 'horizontal'. Attributes ---------- sigLookupTableChanged : signal Emits the HistogramLUTItem itself when the gradient changes sigLevelsChanged : signal Emits the HistogramLUTItem itself while the movable region is changing sigLevelChangeFinished : signal Emits the HistogramLUTItem itself when the movable region is finished changing See Also -------- :class:`~pyqtgraph.ImageItem` HistogramLUTItem is most useful when paired with an ImageItem. :class:`~pyqtgraph.ImageView` Widget containing a paired ImageItem and HistogramLUTItem. :class:`~pyqtgraph.HistogramLUTWidget` QWidget containing a HistogramLUTItem for widget-based layouts. """ sigLookupTableChanged = QtCore.Signal(object) sigLevelsChanged = QtCore.Signal(object) sigLevelChangeFinished = QtCore.Signal(object)
[docs] def __init__(self, image=None, fillHistogram=True, levelMode='mono', gradientPosition='right', orientation='vertical'): GraphicsWidget.__init__(self) self.lut = None self.imageItem = lambda: None # fake a dead weakref self.levelMode = levelMode self.orientation = orientation self.gradientPosition = gradientPosition if orientation == 'vertical' and gradientPosition not in {'right', 'left'}: self.gradientPosition = 'right' elif orientation == 'horizontal' and gradientPosition not in {'top', 'bottom'}: self.gradientPosition = 'bottom' self.layout = QtWidgets.QGraphicsGridLayout() self.setLayout(self.layout) self.layout.setContentsMargins(1, 1, 1, 1) self.layout.setSpacing(0) self.vb = ViewBox(parent=self) if self.orientation == 'vertical': self.vb.setMaximumWidth(152) self.vb.setMinimumWidth(45) self.vb.setMouseEnabled(x=False, y=True) else: self.vb.setMaximumHeight(152) self.vb.setMinimumHeight(45) self.vb.setMouseEnabled(x=True, y=False) self.gradient = GradientEditorItem(orientation=self.gradientPosition) self.gradient.loadPreset('grey') # LinearRegionItem orientation refers to the bounding lines regionOrientation = 'horizontal' if self.orientation == 'vertical' else 'vertical' self.regions = [ # single region for mono levelMode LinearRegionItem([0, 1], regionOrientation, swapMode='block'), # r/g/b/a regions for rgba levelMode LinearRegionItem([0, 1], regionOrientation, swapMode='block', pen='r', brush=fn.mkBrush((255, 50, 50, 50)), span=(0., 1/3.)), LinearRegionItem([0, 1], regionOrientation, swapMode='block', pen='g', brush=fn.mkBrush((50, 255, 50, 50)), span=(1/3., 2/3.)), LinearRegionItem([0, 1], regionOrientation, swapMode='block', pen='b', brush=fn.mkBrush((50, 50, 255, 80)), span=(2/3., 1.)), LinearRegionItem([0, 1], regionOrientation, swapMode='block', pen='w', brush=fn.mkBrush((255, 255, 255, 50)), span=(2/3., 1.)) ] self.region = self.regions[0] # for backward compatibility. for region in self.regions: region.setZValue(1000) self.vb.addItem(region) region.lines[0].addMarker('<|', 0.5) region.lines[1].addMarker('|>', 0.5) region.sigRegionChanged.connect(self.regionChanging) region.sigRegionChangeFinished.connect(self.regionChanged) # gradient position to axis orientation ax = {'left': 'right', 'right': 'left', 'top': 'bottom', 'bottom': 'top'}[self.gradientPosition] self.axis = AxisItem(ax, linkView=self.vb, maxTickLength=-10, parent=self) # axis / viewbox / gradient order in the grid avg = (0, 1, 2) if self.gradientPosition in {'right', 'bottom'} else (2, 1, 0) if self.orientation == 'vertical': self.layout.addItem(self.axis, 0, avg[0]) self.layout.addItem(self.vb, 0, avg[1]) self.layout.addItem(self.gradient, 0, avg[2]) else: self.layout.addItem(self.axis, avg[0], 0) self.layout.addItem(self.vb, avg[1], 0) self.layout.addItem(self.gradient, avg[2], 0) self.gradient.setFlag(self.gradient.GraphicsItemFlag.ItemStacksBehindParent) self.vb.setFlag(self.gradient.GraphicsItemFlag.ItemStacksBehindParent) self.gradient.sigGradientChanged.connect(self.gradientChanged) self.vb.sigRangeChanged.connect(self.viewRangeChanged) comp = QtGui.QPainter.CompositionMode.CompositionMode_Plus self.plots = [ PlotCurveItem(pen=(200, 200, 200, 100)), # mono PlotCurveItem(pen=(255, 0, 0, 100), compositionMode=comp), # r PlotCurveItem(pen=(0, 255, 0, 100), compositionMode=comp), # g PlotCurveItem(pen=(0, 0, 255, 100), compositionMode=comp), # b PlotCurveItem(pen=(200, 200, 200, 100), compositionMode=comp), # a ] self.plot = self.plots[0] # for backward compatibility. for plot in self.plots: if self.orientation == 'vertical': plot.setRotation(90) self.vb.addItem(plot) self.fillHistogram(fillHistogram) self._showRegions() self.autoHistogramRange() if image is not None: self.setImageItem(image)
[docs] def fillHistogram(self, fill=True, level=0.0, color=(100, 100, 200)): """Control fill of the histogram curve(s). Parameters ---------- fill : bool, optional Set whether or not the histogram should be filled. level : float, optional Set the fill level. See :meth:`PlotCurveItem.setFillLevel <pyqtgraph.PlotCurveItem.setFillLevel>`. Only used if ``fill`` is True. color : color, optional Color to use for the fill when the histogram ``levelMode == "mono"``. See :meth:`PlotCurveItem.setBrush <pyqtgraph.PlotCurveItem.setBrush>`. """ colors = [color, (255, 0, 0, 50), (0, 255, 0, 50), (0, 0, 255, 50), (255, 255, 255, 50)] for color, plot in zip(colors, self.plots): if fill: plot.setFillLevel(level) plot.setBrush(color) else: plot.setFillLevel(None)
def paint(self, p, *args): # paint the bounding edges of the region item and gradient item with lines # connecting them if self.levelMode != 'mono' or not self.region.isVisible(): return pen = self.region.lines[0].pen mn, mx = self.getLevels() vbc = self.vb.viewRect().center() gradRect = self.gradient.mapRectToParent(self.gradient.gradRect.rect()) if self.orientation == 'vertical': p1mn = self.vb.mapFromViewToItem(self, Point(vbc.x(), mn)) + Point(0, 5) p1mx = self.vb.mapFromViewToItem(self, Point(vbc.x(), mx)) - Point(0, 5) if self.gradientPosition == 'right': p2mn = gradRect.bottomLeft() p2mx = gradRect.topLeft() else: p2mn = gradRect.bottomRight() p2mx = gradRect.topRight() else: p1mn = self.vb.mapFromViewToItem(self, Point(mn, vbc.y())) - Point(5, 0) p1mx = self.vb.mapFromViewToItem(self, Point(mx, vbc.y())) + Point(5, 0) if self.gradientPosition == 'bottom': p2mn = gradRect.topLeft() p2mx = gradRect.topRight() else: p2mn = gradRect.bottomLeft() p2mx = gradRect.bottomRight() p.setRenderHint(QtGui.QPainter.RenderHint.Antialiasing) for pen in [fn.mkPen((0, 0, 0, 100), width=3), pen]: p.setPen(pen) # lines from the linear region item bounds to the gradient item bounds p.drawLine(p1mn, p2mn) p.drawLine(p1mx, p2mx) # lines bounding the edges of the gradient item if self.orientation == 'vertical': p.drawLine(gradRect.topLeft(), gradRect.topRight()) p.drawLine(gradRect.bottomLeft(), gradRect.bottomRight()) else: p.drawLine(gradRect.topLeft(), gradRect.bottomLeft()) p.drawLine(gradRect.topRight(), gradRect.bottomRight())
[docs] def setHistogramRange(self, mn, mx, padding=0.1): """Set the Y range on the histogram plot. This disables auto-scaling.""" if self.orientation == 'vertical': self.vb.enableAutoRange(self.vb.YAxis, False) self.vb.setYRange(mn, mx, padding) else: self.vb.enableAutoRange(self.vb.XAxis, False) self.vb.setXRange(mn, mx, padding)
[docs] def autoHistogramRange(self): """Enable auto-scaling on the histogram plot.""" self.vb.enableAutoRange(self.vb.XYAxes)
[docs] def disableAutoHistogramRange(self): """Disable auto-scaling on the histogram plot.""" self.vb.disableAutoRange(self.vb.XYAxes)
[docs] def setImageItem(self, img): """Set an ImageItem to have its levels and LUT automatically controlled by this HistogramLUTItem. """ self.imageItem = weakref.ref(img) img.sigImageChanged.connect(self.imageChanged) self._setImageLookupTable() self.regionChanged() self.imageChanged(autoLevel=True)
def viewRangeChanged(self): self.update() def gradientChanged(self): if self.imageItem() is not None: self._setImageLookupTable() self.lut = None self.sigLookupTableChanged.emit(self) def _setImageLookupTable(self): if self.gradient.isLookupTrivial(): self.imageItem().setLookupTable(None) else: self.imageItem().setLookupTable(self.getLookupTable)
[docs] def getLookupTable(self, img=None, n=None, alpha=None): """Return a lookup table from the color gradient defined by this HistogramLUTItem. """ if self.levelMode != 'mono': return None if n is None: if img.dtype == np.uint8: n = 256 else: n = 512 if self.lut is None: self.lut = self.gradient.getLookupTable(n, alpha=alpha) return self.lut
def regionChanged(self): if self.imageItem() is not None: self.imageItem().setLevels(self.getLevels()) self.sigLevelChangeFinished.emit(self) def regionChanging(self): if self.imageItem() is not None: self.imageItem().setLevels(self.getLevels()) self.update() self.sigLevelsChanged.emit(self) def imageChanged(self, autoLevel=False, autoRange=False): if self.imageItem() is None: return if self.levelMode == 'mono': for plt in self.plots[1:]: plt.setVisible(False) self.plots[0].setVisible(True) # plot one histogram for all image data profiler = debug.Profiler() h = self.imageItem().getHistogram() profiler('get histogram') if h[0] is None: return self.plot.setData(*h) profiler('set plot') if autoLevel: mn = h[0][0] mx = h[0][-1] self.region.setRegion([mn, mx]) profiler('set region') else: mn, mx = self.imageItem().levels self.region.setRegion([mn, mx]) else: # plot one histogram for each channel self.plots[0].setVisible(False) ch = self.imageItem().getHistogram(perChannel=True) if ch[0] is None: return for i in range(1, 5): if len(ch) >= i: h = ch[i-1] self.plots[i].setVisible(True) self.plots[i].setData(*h) if autoLevel: mn = h[0][0] mx = h[0][-1] self.regions[i].setRegion([mn, mx]) else: # hide channels not present in image data self.plots[i].setVisible(False) # make sure we are displaying the correct number of channels self._showRegions()
[docs] def getLevels(self): """Return the min and max levels. For rgba mode, this returns a list of the levels for each channel. """ if self.levelMode == 'mono': return self.region.getRegion() else: nch = self.imageItem().channels() if nch is None: nch = 3 return [r.getRegion() for r in self.regions[1:nch+1]]
[docs] def setLevels(self, min=None, max=None, rgba=None): """Set the min/max (bright and dark) levels. Parameters ---------- min : float, optional Minimum level. max : float, optional Maximum level. rgba : list, optional Sequence of (min, max) pairs for each channel for 'rgba' mode. """ if None in {min, max} and (rgba is None or None in rgba[0]): raise ValueError("Must specify min and max levels") if self.levelMode == 'mono': if min is None: min, max = rgba[0] self.region.setRegion((min, max)) else: if rgba is None: rgba = 4*[(min, max)] for levels, region in zip(rgba, self.regions[1:]): region.setRegion(levels)
[docs] def setLevelMode(self, mode): """Set the method of controlling the image levels offered to the user. Options are 'mono' or 'rgba'. """ if mode not in {'mono', 'rgba'}: raise ValueError(f"Level mode must be one of {{'mono', 'rgba'}}, got {mode}") if mode == self.levelMode: return oldLevels = self.getLevels() self.levelMode = mode self._showRegions() # do our best to preserve old levels if mode == 'mono': levels = np.array(oldLevels).mean(axis=0) self.setLevels(*levels) else: levels = [oldLevels] * 4 self.setLevels(rgba=levels) # force this because calling self.setLevels might not set the imageItem # levels if there was no change to the region item self.imageItem().setLevels(self.getLevels()) self.imageChanged() self.update()
def _showRegions(self): for i in range(len(self.regions)): self.regions[i].setVisible(False) if self.levelMode == 'rgba': nch = 4 if self.imageItem() is not None: # Only show rgb channels if connected image lacks alpha. nch = self.imageItem().channels() if nch is None: nch = 3 xdif = 1.0 / nch for i in range(1, nch+1): self.regions[i].setVisible(True) self.regions[i].setSpan((i-1) * xdif, i * xdif) self.gradient.hide() elif self.levelMode == 'mono': self.regions[0].setVisible(True) else: raise ValueError(f"Unknown level mode {self.levelMode}") def saveState(self): return { 'gradient': self.gradient.saveState(), 'levels': self.getLevels(), 'mode': self.levelMode, } def restoreState(self, state): if 'mode' in state: self.setLevelMode(state['mode']) self.gradient.restoreState(state['gradient']) self.setLevels(*state['levels'])