diff --git a/dap/algos/thresh.py b/dap/algos/thresh.py
index 844b995..66ac3b1 100644
--- a/dap/algos/thresh.py
+++ b/dap/algos/thresh.py
@@ -6,17 +6,16 @@ def calc_apply_threshold(results, data, value=None, copy=False):
     if not apply_threshold:
         return data
 
-    for k in ("threshold_min", "threshold_max"):
-        if k not in results:
-            return data
+    threshold_min = results.get("threshold_min")
+    threshold_max = results.get("threshold_max")
+
+    if threshold_min is None and threshold_max is None:
+        return data
 
     if value is None:
         threshold_value = results.get("threshold_value", "NaN")
         value = 0 if threshold_value == "0" else np.nan #TODO
 
-    threshold_min = float(results["threshold_min"])
-    threshold_max = float(results["threshold_max"])
-
     if copy:
         data = data.copy() # do the following in-place changes on a copy
 
@@ -30,10 +29,13 @@ def threshold(data, vmin, vmax, replacement):
     """
     threshold data in place by replacing values < vmin and values > vmax with replacement
     """
-    # if vmin > vmax, data will be overwritten entirely -- better to ensure vmin < vmax by switching them if needed
-    vmin, vmax = sorted((vmin, vmax))
-    data[data < vmin] = replacement
-    data[data > vmax] = replacement
+    if vmin is not None and vmax is not None:
+        # if vmin > vmax, data will be overwritten entirely -- better to ensure vmin < vmax by switching them if needed
+        vmin, vmax = sorted((vmin, vmax))
+    if vmin is not None:
+        data[data < vmin] = replacement
+    if vmax is not None:
+        data[data > vmax] = replacement