Fixed #5 for TWFix32 conversion exception in extension method.

NTwain/TwainSessionExtensions.cs

@@ -372,7 +372,8 @@ namespace NTwain
         /// <returns></returns>
         public static IList<TWFix32> CapGetDPIs(this TwainSession session)
         {
-            return session.GetCapabilityValues(CapabilityId.ICapXResolution).Cast<TWFix32>().ToList();
+            var list = session.GetCapabilityValues(CapabilityId.ICapXResolution);
+            return list.Select(o => o.ConvertToFix32()).ToList();
         }
 
         /// <summary>

NTwain/Values/ValueConverter.cs

@@ -1,4 +1,5 @@
-using System;
+using NTwain.Data;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
@@ -67,5 +68,19 @@ namespace NTwain.Values
         {
             return (ushort)(value >> 16);
         }
+
+        /// <summary>
+        /// Tries to convert to a value to <see cref="TWFix32"/> if possible.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        /// <returns></returns>
+        public static TWFix32 ConvertToFix32(this object value)
+        {
+            if (value is TWFix32)
+            {
+                return (TWFix32)value;
+            }
+            return (TWFix32)Convert.ToSingle(value);
+        }
     }
 }