Source code for pyqtgraph.graphicsItems.HistogramLUTItem

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

from ..Qt import QtGui, QtCore
from .. import functions as fn
from .GraphicsWidget import GraphicsWidget
from .ViewBox import *
from .GradientEditorItem import *
from .LinearRegionItem import *
from .PlotDataItem import *
from .AxisItem import *
from .GridItem import *
from ..Point import Point
from .. import functions as fn
import numpy as np
from .. import debug as debug

import weakref

__all__ = ['HistogramLUTItem']

[docs]class HistogramLUTItem(GraphicsWidget): """ This is a graphicsWidget which provides controls for adjusting the display of an image. Includes: - Image histogram - Movable region over histogram to select black/white levels - Gradient editor to define color lookup table for single-channel images Parameters ---------- image : ImageItem or None If *image* is provided, then the control will be automatically linked to the image and changes to the control will be immediately reflected in the image's appearance. fillHistogram : bool By default, the histogram is rendered with a fill. For performance, set *fillHistogram* = False. rgbHistogram : bool Sets whether the histogram is computed once over all channels of the image, or once per channel. levelMode : 'mono' or 'rgba' If 'mono', then only a single set of black/whilte level lines is drawn, and the levels apply to all channels in the image. If 'rgba', then one set of levels is drawn for each channel. """ sigLookupTableChanged = QtCore.Signal(object) sigLevelsChanged = QtCore.Signal(object) sigLevelChangeFinished = QtCore.Signal(object)
[docs] def __init__(self, image=None, fillHistogram=True, rgbHistogram=False, levelMode='mono'): GraphicsWidget.__init__(self) self.lut = None self.imageItem = lambda: None # fake a dead weakref self.levelMode = levelMode self.rgbHistogram = rgbHistogram self.layout = QtGui.QGraphicsGridLayout() self.setLayout(self.layout) self.layout.setContentsMargins(1,1,1,1) self.layout.setSpacing(0) self.vb = ViewBox(parent=self) self.vb.setMaximumWidth(152) self.vb.setMinimumWidth(45) self.vb.setMouseEnabled(x=False, y=True) self.gradient = GradientEditorItem() self.gradient.setOrientation('right') self.gradient.loadPreset('grey') self.regions = [ LinearRegionItem([0, 1], 'horizontal', swapMode='block'), LinearRegionItem([0, 1], 'horizontal', swapMode='block', pen='r', brush=fn.mkBrush((255, 50, 50, 50)), span=(0., 1/3.)), LinearRegionItem([0, 1], 'horizontal', swapMode='block', pen='g', brush=fn.mkBrush((50, 255, 50, 50)), span=(1/3., 2/3.)), LinearRegionItem([0, 1], 'horizontal', swapMode='block', pen='b', brush=fn.mkBrush((50, 50, 255, 80)), span=(2/3., 1.)), LinearRegionItem([0, 1], 'horizontal', swapMode='block', pen='w', brush=fn.mkBrush((255, 255, 255, 50)), span=(2/3., 1.))] 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) self.region = self.regions[0] # for backward compatibility. self.axis = AxisItem('left', linkView=self.vb, maxTickLength=-10, parent=self) self.layout.addItem(self.axis, 0, 0) self.layout.addItem(self.vb, 0, 1) self.layout.addItem(self.gradient, 0, 2) self.range = None self.gradient.setFlag(self.gradient.ItemStacksBehindParent) self.vb.setFlag(self.gradient.ItemStacksBehindParent) self.gradient.sigGradientChanged.connect(self.gradientChanged) self.vb.sigRangeChanged.connect(self.viewRangeChanged) add = QtGui.QPainter.CompositionMode_Plus self.plots = [ PlotCurveItem(pen=(200, 200, 200, 100)), # mono PlotCurveItem(pen=(255, 0, 0, 100), compositionMode=add), # r PlotCurveItem(pen=(0, 255, 0, 100), compositionMode=add), # g PlotCurveItem(pen=(0, 0, 255, 100), compositionMode=add), # b PlotCurveItem(pen=(200, 200, 200, 100), compositionMode=add), # a ] self.plot = self.plots[0] # for backward compatibility. for plot in self.plots: plot.rotate(90) self.vb.addItem(plot) self.fillHistogram(fillHistogram) self._showRegions() self.vb.addItem(self.plot) self.autoHistogramRange() if image is not None: self.setImageItem(image)
def fillHistogram(self, fill=True, level=0.0, color=(100, 100, 200)): colors = [color, (255, 0, 0, 50), (0, 255, 0, 50), (0, 0, 255, 50), (255, 255, 255, 50)] for i,plot in enumerate(self.plots): if fill: plot.setFillLevel(level) plot.setBrush(colors[i]) else: plot.setFillLevel(None) def paint(self, p, *args): if self.levelMode != 'mono': return pen = self.region.lines[0].pen rgn = self.getLevels() p1 = self.vb.mapFromViewToItem(self, Point(self.vb.viewRect().center().x(), rgn[0])) p2 = self.vb.mapFromViewToItem(self, Point(self.vb.viewRect().center().x(), rgn[1])) gradRect = self.gradient.mapRectToParent(self.gradient.gradRect.rect()) for pen in [fn.mkPen((0, 0, 0, 100), width=3), pen]: p.setPen(pen) p.drawLine(p1 + Point(0, 5), gradRect.bottomLeft()) p.drawLine(p2 - Point(0, 5), gradRect.topLeft()) p.drawLine(gradRect.topLeft(), gradRect.topRight()) p.drawLine(gradRect.bottomLeft(), gradRect.bottomRight())
[docs] def setHistogramRange(self, mn, mx, padding=0.1): """Set the Y range on the histogram plot. This disables auto-scaling.""" self.vb.enableAutoRange(self.vb.YAxis, False) self.vb.setYRange(mn, mx, padding)
[docs] def autoHistogramRange(self): """Enable auto-scaling on the histogram plot.""" self.vb.enableAutoRange(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) img.setLookupTable(self.getLookupTable) ## send function pointer, not the result self.regionChanged() self.imageChanged(autoLevel=True)
def viewRangeChanged(self): self.update() def gradientChanged(self): if self.imageItem() is not None: if self.gradient.isLookupTrivial(): self.imageItem().setLookupTable(None) #lambda x: x.astype(np.uint8)) else: self.imageItem().setLookupTable(self.getLookupTable) ## send function pointer, not the result self.lut = None self.sigLookupTableChanged.emit(self)
[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 is not '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.sigLevelsChanged.emit(self) self.update() 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.region[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. Arguments may be *min* and *max* for single-channel data, or *rgba* = [(rmin, rmax), ...] for multi-channel data. """ if self.levelMode == 'mono': if min is None: min, max = rgba[0] assert None not in (min, max) self.region.setRegion((min, max)) else: if rgba is None: raise TypeError("Must specify rgba argument when levelMode != 'mono'.") for i, levels in enumerate(rgba): self.regions[i+1].setRegion(levels)
[docs] def setLevelMode(self, mode): """ Set the method of controlling the image levels offered to the user. Options are 'mono' or 'rgba'. """ assert mode in ('mono', 'rgba') 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': imax = 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("Unknown level mode %r" % self.levelMode) def saveState(self): return { 'gradient': self.gradient.saveState(), 'levels': self.getLevels(), 'mode': self.levelMode, } def restoreState(self, state): self.setLevelMode(state['mode']) self.gradient.restoreState(state['gradient']) self.setLevels(*state['levels'])