diff --git a/pyqtgraph/functions.py b/pyqtgraph/functions.py
index bdbf6d87..1aed6ace 100644
--- a/pyqtgraph/functions.py
+++ b/pyqtgraph/functions.py
@@ -200,7 +200,7 @@ def mkColor(*args):
                 try:
                     return Colors[c]
                 except KeyError:
-                    raise Exception('No color named "%s"' % c)
+                    raise ValueError('No color named "%s"' % c)
             if len(c) == 3:
                 r = int(c[0]*2, 16)
                 g = int(c[1]*2, 16)
@@ -235,18 +235,18 @@ def mkColor(*args):
             elif len(args[0]) == 2:
                 return intColor(*args[0])
             else:
-                raise Exception(err)
+                raise TypeError(err)
         elif type(args[0]) == int:
             return intColor(args[0])
         else:
-            raise Exception(err)
+            raise TypeError(err)
     elif len(args) == 3:
         (r, g, b) = args
         a = 255
     elif len(args) == 4:
         (r, g, b, a) = args
     else:
-        raise Exception(err)
+        raise TypeError(err)
     
     args = [r,g,b,a]
     args = [0 if np.isnan(a) or np.isinf(a) else a for a in args]
@@ -404,22 +404,39 @@ def makeArrowPath(headLen=20, tipAngle=20, tailLen=20, tailWidth=3, baseAngle=0)
     
     
 def eq(a, b):
-    """The great missing equivalence function: Guaranteed evaluation to a single bool value."""
+    """The great missing equivalence function: Guaranteed evaluation to a single bool value.
+    
+    This function has some important differences from the == operator:
+    
+    1. Returns True if a IS b, even if a==b still evaluates to False, such as with nan values.
+    2. Tests for equivalence using ==, but silently ignores some common exceptions that can occur
+       (AtrtibuteError, ValueError).
+    3. When comparing arrays, returns False if the array shapes are not the same.
+    4. When comparing arrays of the same shape, returns True only if all elements are equal (whereas
+       the == operator would return a boolean array).
+    """
     if a is b:
         return True
         
     try:
-        with warnings.catch_warnings(module=np):  # ignore numpy futurewarning (numpy v. 1.10)
-            e = a==b
-    except ValueError:
-        return False
-    except AttributeError: 
+        try:
+            # Sometimes running catch_warnings(module=np) generates AttributeError ???
+            catcher =  warnings.catch_warnings(module=np)  # ignore numpy futurewarning (numpy v. 1.10)
+            catcher.__enter__()
+        except Exception:
+            catcher = None
+        e = a==b
+    except (ValueError, AttributeError): 
         return False
     except:
         print('failed to evaluate equivalence for:')
         print("  a:", str(type(a)), str(a))
         print("  b:", str(type(b)), str(b))
         raise
+    finally:
+        if catcher is not None:
+            catcher.__exit__(None, None, None)
+    
     t = type(e)
     if t is bool:
         return e
diff --git a/pyqtgraph/tests/test_functions.py b/pyqtgraph/tests/test_functions.py
index 7ad3bf91..eff56635 100644
--- a/pyqtgraph/tests/test_functions.py
+++ b/pyqtgraph/tests/test_functions.py
@@ -1,5 +1,6 @@
 import pyqtgraph as pg
 import numpy as np
+import sys
 from numpy.testing import assert_array_almost_equal, assert_almost_equal
 import pytest
 
@@ -293,6 +294,68 @@ def test_makeARGB():
     with AssertExc():  # 3d levels not allowed
         pg.makeARGB(np.zeros((2,2,3), dtype='float'), levels=np.zeros([3, 2, 2]))
 
+
+def test_eq():
+    eq = pg.functions.eq
+    
+    zeros = [0, 0.0, np.float(0), np.int(0)]
+    if sys.version[0] < '3':
+        zeros.append(long(0))
+    for i,x in enumerate(zeros):
+        for y in zeros[i:]:
+            assert eq(x, y)
+            assert eq(y, x)
+    
+    assert eq(np.nan, np.nan)
+    
+    # test 
+    class NotEq(object):
+        def __eq__(self, x):
+            return False
+        
+    noteq = NotEq()
+    assert eq(noteq, noteq) # passes because they are the same object
+    assert not eq(noteq, NotEq())
+
+
+    # Should be able to test for equivalence even if the test raises certain
+    # exceptions
+    class NoEq(object):
+        def __init__(self, err):
+            self.err = err
+        def __eq__(self, x):
+            raise self.err
+        
+    noeq1 = NoEq(AttributeError())
+    noeq2 = NoEq(ValueError())
+    noeq3 = NoEq(Exception())
+    
+    assert eq(noeq1, noeq1)
+    assert not eq(noeq1, noeq2)
+    assert not eq(noeq2, noeq1)
+    with pytest.raises(Exception):
+        eq(noeq3, noeq2)
+
+    # test array equivalence
+    # note that numpy has a weird behavior here--np.all() always returns True
+    # if one of the arrays has size=0; eq() will only return True if both arrays
+    # have the same shape.
+    a1 = np.zeros((10, 20)).astype('float')
+    a2 = a1 + 1
+    a3 = a2.astype('int')
+    a4 = np.empty((0, 20))
+    assert not eq(a1, a2)
+    assert not eq(a1, a3)
+    assert not eq(a1, a4)
+
+    assert eq(a2, a3)
+    assert not eq(a2, a4)
+    
+    assert not eq(a3, a4)
+    
+    assert eq(a4, a4.copy())
+    assert not eq(a4, a4.T)
+
     
 if __name__ == '__main__':
     test_interpolateArray()
\ No newline at end of file