diff --git a/lightsim/openglsim.py b/lightsim/openglsim.py
--- a/lightsim/openglsim.py
+++ b/lightsim/openglsim.py
@@ -1,38 +1,56 @@
 # see http://www.sgi.com/software/opengl/advanced97/notes/node57.html for accum notes
 
-import sys
-from Image import *
+import sys, time
+import numpy as num
 from OpenGL.GL import *
 from OpenGL.Tk import *
+import Image
+
+def drawWithAlpha(imgString, w, h, alpha):
+    """without opengl extensions"""
+    t = time.time()
+    ar = num.reshape(num.fromstring(imgString, dtype='uint8'),
+                     (w * h, 4))
+    print "  tonum", time.time() - t
+    ar[:,3] *= alpha
+
+    print "  scl", time.time() - t
+    glDrawPixels(w, h,
+                 GL_RGBA, GL_UNSIGNED_BYTE, ar.tostring())
+    print "  draw", time.time() - t
+  
 
 class Surface:
   def Display(self, event=None):
-
+    assert 'GL_ARB_imaging' in glGetString(GL_EXTENSIONS).split()
+    
     glClearColor(0.0, 0.0, 0.0, 0)
     glClear( GL_COLOR_BUFFER_BIT |GL_ACCUM_BUFFER_BIT)
-
+    glEnable(GL_BLEND)
+    #glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
+    glBlendFunc(GL_SRC_ALPHA, GL_DST_ALPHA)
     l=glGenLists(1)
     glNewList(l,GL_COMPILE)
     glEndList()
 
 #    glDrawBuffer(GL_BACK)
                 
-    for x in range(1,2):
-
+    for x, img in enumerate(self.image):
       mag = self.scales[x].get()
       print "pic %i at %f" % (x,mag)
-      glClear(GL_COLOR_BUFFER_BIT)
-      glDrawPixels(self.imageWidth, self.imageHeight, GL_RGB, GL_UNSIGNED_BYTE, self.image[x])
+#      glClear(GL_COLOR_BUFFER_BIT)
+      #glBlendColor(1, 1, 1, mag) # needs ARB_imaging
+      drawWithAlpha(img, self.imageWidth, self.imageHeight, mag)
+
 
-      if x==0:
-        glAccum(GL_LOAD,mag)
-      else:
-        glAccum(GL_ACCUM,mag)
+##       if x==0:
+##         glAccum(GL_LOAD,mag)
+##       else:
+##         glAccum(GL_ACCUM,mag)
 
       # glAccum(GL_ADD,self.x)
       self.x=(self.x+.1)%2.0
-      print "return"
-      glAccum(GL_RETURN,1)
+##       glAccum(GL_RETURN,1)
 
   def SetupWindow(self):
     self.OglFrame = Frame()
@@ -43,7 +61,7 @@ class Surface:
   
   
   def SetupOpenGL(self):
-    self.ogl = Opengl(master=self.OglFrame, width = 270, height = 270, double = 1, depth = 0)
+    self.ogl = Opengl(master=self.OglFrame, width = 512, height = 270, double = 1, depth = 0)
     self.ogl.pack(side = 'top', expand = 1, fill = 'both')
     self.ogl.set_centerpoint(0, 0, 0)
     self.ogl.redraw = self.Display
@@ -60,11 +78,12 @@ class Surface:
     self.SetupWindow()
   
     self.image=[]
-    for filename in ('pic1.ppm','pic2.ppm'):
-      im = open(filename)
+    for filename in ('skyline/bg.png', 'skyline/cyc-lo-red.png'):
+      im = Image.open(filename)
+      im.thumbnail((200, 200))
       self.imageWidth = im.size[0]
       self.imageHeight = im.size[1]
-      self.image.append(im.tostring("raw", "RGB", 0, -1))
+      self.image.append(im.convert("RGBA").tostring())#"raw", "RGB", 0, -1))
       print self.imageWidth, self.imageHeight, self.imageWidth * self.imageHeight*4, len(self.image)
   
     self.SetupOpenGL()