diff --git a/README.md b/README.md
index 7211620..bdf0cf3 100644
--- a/README.md
+++ b/README.md
@@ -56,6 +56,22 @@ From left to right: reference image, initial state, and optimization process.
 
 ![](https://raw.githubusercontent.com/hiroharu-kato/neural_renderer/master/examples/data/example4_ref.png) ![](https://raw.githubusercontent.com/hiroharu-kato/neural_renderer/master/examples/data/example4_init.png) ![](https://raw.githubusercontent.com/hiroharu-kato/neural_renderer/master/examples/data/example4_result.gif)
 
+## Testing
+
+For development; be sure to use a `virtualenv` when you can!
+
+```sh
+# Build.
+pip install torch
+# - Be sure to set your CUDA environment variables for building the kernels!
+pip install -e .
+
+# Install test deps
+pip install scikit-image
+# Discover / run tests
+cd ./tests
+python -m unittest discover -t .
+```
 
 ## Citation
 
diff --git a/tests/test_rasterize.py b/tests/test_rasterize.py
index 3005b54..4c58b6e 100644
--- a/tests/test_rasterize.py
+++ b/tests/test_rasterize.py
@@ -77,9 +77,11 @@ def test_forward_case3(self):
 
         # load reference image by blender
         ref = imread(os.path.join(data_dir, 'teapot_blender.png'))
-        ref = (ref.min(axis=-1) != 255).astype(np.float32)
+        ref = utils.guess_foreground_mask(ref)
 
-        assert(np.allclose(ref, image))
+        image = image.astype(bool)
+        iou = utils.calc_mask_iou(image.astype(bool), ref)
+        self.assertGreater(iou, 0.999)
 
     def test_backward_case1(self):
         """Backward if non-zero gradient is out of a face."""
diff --git a/tests/test_rasterize_depth.py b/tests/test_rasterize_depth.py
index 52b2283..7ce903a 100644
--- a/tests/test_rasterize_depth.py
+++ b/tests/test_rasterize_depth.py
@@ -30,9 +30,10 @@ def test_forward_case1(self):
 
         # load reference image by blender
         ref = imread(os.path.join(data_dir, 'teapot_blender.png'))
-        ref = (ref.min(axis=-1) != 255).astype(np.float32)
+        ref = utils.guess_foreground_mask(ref)
 
-        assert(np.allclose(ref, image))
+        iou = utils.calc_mask_iou(ref, image)
+        self.assertGreater(iou, 0.999)
 
     def test_forward_case2(self):
         # load teapot
@@ -46,12 +47,23 @@ def test_forward_case2(self):
         images = renderer(vertices, faces, mode='depth')
         images = images.detach().cpu().numpy()
         image = images[2]
+        mask = image != image.max()
         image[image == image.max()] = image.min()
         image = (image - image.min()) / (image.max() - image.min())
 
         ref = imread(os.path.join(data_dir, 'test_depth.png')).astype(np.float32) / 255.
+        ref_mask = ref != 0.0
 
-        assert(np.allclose(image, ref, atol=1e-2))
+        iou = utils.calc_mask_iou(ref_mask, mask)
+        self.assertGreater(iou, 0.998)
+
+        # Check difference along intersection (which should be OK-ish).
+        intersect = mask & ref_mask
+        image[~intersect] = 0.0
+        ref[~intersect] = 0.0
+
+        # Shrug.
+        np.testing.assert_allclose(image, ref, atol=0.0089, rtol=0.0)
 
     def test_backward_case1(self):
         vertices = [
diff --git a/tests/test_rasterize_silhouettes.py b/tests/test_rasterize_silhouettes.py
index 63459c5..2e5679b 100644
--- a/tests/test_rasterize_silhouettes.py
+++ b/tests/test_rasterize_silhouettes.py
@@ -30,9 +30,10 @@ def test_case1(self):
 
         # load reference image by blender
         ref = imread(os.path.join(data_dir, 'teapot_blender.png'))
-        ref = (ref.min(-1) != 255).astype(np.float32)
+        ref = utils.guess_foreground_mask(ref)
 
-        assert(np.allclose(ref, image))
+        iou = utils.calc_mask_iou(image.astype(bool), ref)
+        self.assertGreater(iou, 0.999)
 
     def test_backward_case1(self):
         """Backward if non-zero gradient is out of a face."""
diff --git a/tests/utils.py b/tests/utils.py
index 842e33f..85d97db 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -1,5 +1,6 @@
 import os
 
+import numpy as np
 import torch
 
 import neural_renderer as nr
@@ -25,3 +26,19 @@ def load_teapot_batch(batch_size=4, target_num=2):
     textures = torch.ones((faces.shape[0], 4, 4, 4, 3), dtype=torch.float32)
     vertices, faces, textures = to_minibatch((vertices, faces, textures), batch_size, target_num)
     return vertices, faces, textures
+
+def guess_foreground_mask(ref, bg_uv=(0, 0)):
+    assert ref.ndim == 3
+    bg_pixel = ref[bg_uv].reshape((1, 1, -1))
+    return (ref != bg_pixel).any(axis=2)
+
+def calc_mask_iou(a, b):
+    assert a.dtype == bool
+    assert b.dtype == bool
+    assert a.shape == b.shape
+    union = np.sum(a | b)
+    if union == 0.0:
+        return 0.0
+    else:
+        intersect = np.sum(a & b)
+        return intersect / union