Added image analysis example

examples/__main__.py

@@ -26,6 +26,7 @@ examples = OrderedDict([
     ('Crosshair / Mouse interaction', 'crosshair.py'),
     ('Data Slicing', 'DataSlicing.py'),
     ('Plot Customization', 'customPlot.py'),
+    ('Image Analysis', 'imageAnalysis.py'),
     ('Dock widgets', 'dockarea.py'),
     ('Console', 'ConsoleWidget.py'),
     ('Histograms', 'histogram.py'),

examples/imageAnalysis.py

@@ -0,0 +1,98 @@
+# -*- coding: utf-8 -*-
+"""
+Demonstrates common image analysis tools.
+
+Many of the features demonstrated here are already provided by the ImageView
+widget, but here we present a lower-level approach that provides finer control
+over the user interface.
+"""
+import initExample ## Add path to library (just for examples; you do not need this)
+
+import pyqtgraph as pg
+from pyqtgraph.Qt import QtCore, QtGui
+import numpy as np
+
+pg.mkQApp()
+
+win = pg.GraphicsLayoutWidget()
+win.setWindowTitle('pyqtgraph example: Image Analysis')
+
+# A plot area (ViewBox + axes) for displaying the image
+p1 = win.addPlot()
+
+# Item for displaying image data
+img = pg.ImageItem()
+p1.addItem(img)
+
+# Custom ROI for selecting an image region
+roi = pg.ROI([-8, 14], [6, 5])
+roi.addScaleHandle([0.5, 1], [0.5, 0.5])
+roi.addScaleHandle([0, 0.5], [0.5, 0.5])
+p1.addItem(roi)
+roi.setZValue(10)  # make sure ROI is drawn above image
+
+# Isocurve drawing
+iso = pg.IsocurveItem(level=0.8, pen='g')
+iso.setParentItem(img)
+iso.setZValue(5)
+
+# Contrast/color control
+hist = pg.HistogramLUTItem()
+hist.setImageItem(img)
+win.addItem(hist)
+
+# Draggable line for setting isocurve level
+isoLine = pg.InfiniteLine(angle=0, movable=True, pen='g')
+hist.vb.addItem(isoLine)
+hist.vb.setMouseEnabled(y=False) # makes user interaction a little easier
+isoLine.setValue(0.8)
+isoLine.setZValue(1000) # bring iso line above contrast controls
+
+# Another plot area for displaying ROI data
+win.nextRow()
+p2 = win.addPlot(colspan=2)
+p2.setMaximumHeight(250)
+win.resize(800, 800)
+win.show()
+
+
+# Generate image data
+data = np.random.normal(size=(100, 200))
+data[20:80, 20:80] += 2.
+data = pg.gaussianFilter(data, (3, 3))
+data += np.random.normal(size=(100, 200)) * 0.1
+img.setImage(data)
+hist.setLevels(data.min(), data.max())
+
+# build isocurves from smoothed data
+iso.setData(pg.gaussianFilter(data, (2, 2)))
+
+# set position and scale of image
+img.scale(0.2, 0.2)
+img.translate(-50, 0)
+
+# zoom to fit imageo
+p1.autoRange()  
+
+
+# Callbacks for handling user interaction
+def updatePlot():
+    global img, roi, data, p2
+    selected = roi.getArrayRegion(data, img)
+    p2.plot(selected.mean(axis=1), clear=True)
+
+roi.sigRegionChanged.connect(updatePlot)
+updatePlot()
+
+def updateIsocurve():
+    global isoLine, iso
+    iso.setLevel(isoLine.value())
+
+isoLine.sigDragged.connect(updateIsocurve)
+
+
+## Start Qt event loop unless running in interactive mode or using pyside.
+if __name__ == '__main__':
+    import sys
+    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
+        QtGui.QApplication.instance().exec_()

pyqtgraph/graphicsItems/IsocurveItem.py

@@ -35,11 +35,6 @@ class IsocurveItem(GraphicsObject):
         self.setPen(pen)
         self.setData(data, level)
         
-        
-
-        #if data is not None and level is not None:
-            #self.updateLines(data, level)
-            
     
     def setData(self, data, level=None):
         """
@@ -65,6 +60,7 @@ class IsocurveItem(GraphicsObject):
         """Set the level at which the isocurve is drawn."""
         self.level = level
         self.path = None
+        self.prepareGeometryChange()
         self.update()