diff --git a/displayarray/frame_publising/frame_update_thread.py b/displayarray/frame_publising/frame_update_thread.py
index fdd79cc..9707c9d 100644
--- a/displayarray/frame_publising/frame_update_thread.py
+++ b/displayarray/frame_publising/frame_update_thread.py
@@ -47,10 +47,6 @@ class VideoHandlerThread(threading.Thread):
             for c in self.callbacks:
                 try:
                     frame_c = c(frame)
-                except TypeError as te:
-                    raise TypeError(
-                        "Callback functions for cvpubsub need to accept two arguments: array and uid"
-                    )
                 except Exception as e:
                     self.exception_raised = e
                     frame = frame_c = self.exception_raised
diff --git a/examples/test_simple_api.py b/examples/test_simple_api.py
index cd8afda..097361c 100644
--- a/examples/test_simple_api.py
+++ b/examples/test_simple_api.py
@@ -95,3 +95,136 @@ class TestSubWin(ut.TestCase):
             autoencoder.fit(grab_noise, grab, steps_per_epoch=1, epochs=1)
             output_image = autoencoder.predict(grab, steps=1)
             displayer.update((output_image[0] * 255.0).astype(np.uint8), "uid for autoencoder output")
+
+    def test_lens_construction(self):
+        from displayarray import display
+        import numpy as np
+
+        center = (75, 450)
+        zoom = .5
+        zoom_out = 1.0 / zoom
+
+        arr = np.random.uniform(0, 1, (300, 600, 3))
+        display(arr, blocking=True)
+
+        y = np.arange(arr.shape[0])
+        x = np.arange(arr.shape[1])
+        y_ = (y - center[0]) * zoom_out / arr.shape[0]
+        x_ = (x - center[1]) * zoom_out / arr.shape[1]
+        p = np.array(np.meshgrid(x_, y_))
+        display(p[0] + .5, blocking=True)
+        display(p[1] + .5, blocking=True)
+
+        barrel_power = 1.5
+
+        theta = np.arctan2(p[1], p[0])
+        display((theta + (np.pi / 2.0)) / (np.pi / 2.0), blocking=True)
+
+        radius = np.linalg.norm(p, axis=0)
+        print(radius.shape)
+        display(radius, blocking=True)
+
+        radius = pow(radius, barrel_power)
+        display(radius, blocking=True)
+
+        print(len(x))
+        x_new = 0.5 * (radius * np.cos(theta) + 1)
+        display(x_new, blocking=True)
+        x_new = np.clip(x_new * len(x), 0, len(x) - 1)
+        display(x_new / float(len(x)), blocking=True)
+
+        y_new = 0.5 * (radius * np.sin(theta) + 1)
+        display(y_new, blocking=True)
+        y_new = np.clip(y_new * len(y), 0, len(y) - 1)
+
+        p = np.array(np.meshgrid(y, x)).astype(np.uint32)
+
+        p_new = np.array((y_new, x_new)).astype(np.uint32)
+
+        arr[p[0], p[1], :] = np.swapaxes(arr[p_new[0], p_new[1], :], 0, 1)
+        display(arr, blocking=True)
+
+    def test_display_lens(self):
+        from displayarray import display
+        from displayarray.input import mouse_loop
+        import numpy as np
+        import cv2
+        import skimage.measure
+        import skimage.transform
+
+        def lens(arr):
+            center = lens.center
+            zoom = lens.zoom
+            zoom_out = 1.0 / zoom[0]
+            if not isinstance(lens.bleed[0], np.ndarray):
+                lens.bleed[0] = np.zeros_like(arr)
+
+            y = np.arange(arr.shape[0])
+            x = np.arange(arr.shape[1])
+            y_ = (y - arr.shape[0] / 2.0) * zoom_out / arr.shape[0]
+            x_ = (x - arr.shape[1] / 2.0) * zoom_out / arr.shape[1]
+            p = np.array(np.meshgrid(x_, y_))
+
+            y2_ = (y - center[0]) * zoom_out / arr.shape[0]
+            x2_ = (x - center[1]) * zoom_out / arr.shape[1]
+            p2 = np.array(np.meshgrid(x2_, y2_))
+
+            barrel_power = lens.power[0]
+
+            theta = np.arctan2(p2[1], p2[0])
+
+            radius = np.linalg.norm(p2, axis=0)
+
+            radius = pow(radius, barrel_power)
+
+            x_new = 0.5 * (radius * np.cos(theta) + 1)
+            x_new = np.clip(x_new * len(x), 0, len(x) - 1)
+
+            y_new = 0.5 * (radius * np.sin(theta) + 1)
+            y_new = np.clip(y_new * len(y), 0, len(y) - 1)
+
+            p = np.array(np.meshgrid(y, x)).astype(np.uint32)
+
+            p_new = np.array((y_new, x_new)).astype(np.uint32)
+
+            # arr[p[0], p[1], :] = np.swapaxes(arr[p_new[0], p_new[1], :], 0, 1)
+            arr2 = lens.bleed[0].copy()
+            arr2[y,...] = (arr2[y,...] + arr2[(y+1)%len(y), ...])/2
+            arr2[y, ...] = (arr2[y, ...] + arr2[(y - 1) % len(y), ...]) / 2
+            arr2[:,x, ...] = (arr2[:,x, ...] + arr2[:, (x + 1) % len(x), ...]) / 2
+            arr2[:,x, ...] = (arr2[:,x, ...] + arr2[:, (x - 1) % len(x), ...]) / 2
+            #arr2 = np.zeros_like(arr)
+            arr2[p_new[0], p_new[1], :] = np.swapaxes(arr[p[0], p[1], :], 0, 1)
+            #lens.bleed[0][p_new[0], p_new[1], :] = np.swapaxes(arr[p[0], p[1], :], 0, 1)
+            #avg = skimage.measure.block_reduce(arr2, (2,2, 1), np.min)
+            #avg2 = skimage.transform.resize(avg, (arr2.shape))
+            lens.bleed[0]=arr2
+            #lens.bleed
+
+            return arr2
+
+        lens.center = [250, 250]
+        lens.zoom = [.5]
+        lens.power = [1.0]
+        lens.bleed = [None]
+
+        @mouse_loop
+        def m_loop(me):
+            m_loop.center[:] = [me.y, me.x]
+            if me.event == cv2.EVENT_MOUSEWHEEL:
+                if me.flags & cv2.EVENT_FLAG_CTRLKEY:
+                    if me.flags > 0:
+                        m_loop.zoom[0] *= 1.1
+                    else:
+                        m_loop.zoom[0] /= 1.1
+                else:
+                    if me.flags > 0:
+                        m_loop.power[0] *= 1.1
+                    else:
+                        m_loop.power[0] /= 1.1
+
+        m_loop.center = lens.center
+        m_loop.zoom = lens.zoom
+        m_loop.power = lens.power
+
+        display("fractal test.mp4", callbacks=lens, blocking=True)