ImageItem performance boost by avoiding makeQImage(transpose=True)

pyqtgraph/functions.py

@@ -875,6 +875,9 @@ def makeARGB(data, lut=None, levels=None, scale=None, useRGBA=False):
         order = [2,1,0,3] ## for some reason, the colors line up as BGR in the final image.
         
     if data.ndim == 2:
+        # This is tempting:
+        #   imgData[..., :3] = data[..., np.newaxis]
+        # ..but it turns out this is faster:
         for i in range(3):
             imgData[..., i] = data
     elif data.shape[2] == 1:

pyqtgraph/graphicsItems/ImageItem.py

@@ -260,8 +260,8 @@ class ImageItem(GraphicsObject):
         #print lut.shape
         #print self.lut
             
-        argb, alpha = fn.makeARGB(self.image, lut=lut, levels=self.levels)
-        self.qimage = fn.makeQImage(argb, alpha)
+        argb, alpha = fn.makeARGB(self.image.T, lut=lut, levels=self.levels)
+        self.qimage = fn.makeQImage(argb, alpha, transpose=False)
         prof.finish()