diff --git a/src/UglyToad.PdfPig/Filters/CcittFaxCompressionType.cs b/src/UglyToad.PdfPig/Filters/CcittFaxCompressionType.cs
index da388445..f0f372de 100644
--- a/src/UglyToad.PdfPig/Filters/CcittFaxCompressionType.cs
+++ b/src/UglyToad.PdfPig/Filters/CcittFaxCompressionType.cs
@@ -6,16 +6,20 @@
     internal enum CcittFaxCompressionType
     {
         /// <summary>
-        /// Modified Huffman - Group 3 (T4)
+        /// Modified Huffman (MH) - Group 3 variation (T2)
         /// </summary>
         ModifiedHuffman,
         /// <summary>
-        /// Modified Read - Group 3 (optional T4)
+        /// Modified Huffman (MH) - Group 3 (T4)
         /// </summary>
-        T4,
+        Group3_1D,
         /// <summary>
-        /// Modified Modified Read - Group 4 (T6)
+        /// Modified Read (MR) - Group 3 (T4)
         /// </summary>
-        T6
+        Group3_2D,
+        /// <summary>
+        /// Modified Modified Read (MMR) - Group 4 (T6)
+        /// </summary>
+        Group4_2D
     }
 }
diff --git a/src/UglyToad.PdfPig/Filters/CcittFaxDecodeFilter.cs b/src/UglyToad.PdfPig/Filters/CcittFaxDecodeFilter.cs
index 9fe84246..8cae7dd7 100644
--- a/src/UglyToad.PdfPig/Filters/CcittFaxDecodeFilter.cs
+++ b/src/UglyToad.PdfPig/Filters/CcittFaxDecodeFilter.cs
@@ -60,7 +60,7 @@
         {
             if (k == 0)
             {
-                var compressionType = CcittFaxCompressionType.T4; // Group 3 1D
+                var compressionType = CcittFaxCompressionType.Group3_1D; // Group 3 1D
 
                 if (input.Count < 20)
                 {
@@ -78,7 +78,7 @@
                         b = (short)((b << 1) + ((input[(i / 8)] >> (7 - (i % 8))) & 0x01));
                         if ((b & 0xFFF) == 1)
                         {
-                            return CcittFaxCompressionType.T4;
+                            return CcittFaxCompressionType.Group3_1D;
                         }
                     }
                 }
@@ -88,11 +88,11 @@
             else if (k > 0)
             {
                 // Group 3 2D
-                return CcittFaxCompressionType.T4;
+                return CcittFaxCompressionType.Group3_2D;
             }
             else
             {
-                return CcittFaxCompressionType.T6;
+                return CcittFaxCompressionType.Group4_2D;
             }
         }
 
diff --git a/src/UglyToad.PdfPig/Filters/CcittFaxDecoderStream.cs b/src/UglyToad.PdfPig/Filters/CcittFaxDecoderStream.cs
index 71aff5d8..89982af1 100644
--- a/src/UglyToad.PdfPig/Filters/CcittFaxDecoderStream.cs
+++ b/src/UglyToad.PdfPig/Filters/CcittFaxDecoderStream.cs
@@ -17,7 +17,6 @@
         private readonly int columns;
         private readonly byte[] decodedRow;
 
-        private readonly bool optionG32D;
         private readonly bool optionByteAligned;
         
         private readonly CcittFaxCompressionType type;
@@ -52,20 +51,6 @@
             changesCurrentRow = new int[columns + 2];
 
             optionByteAligned = byteAligned;
-            switch (type)
-            {
-                case CcittFaxCompressionType.ModifiedHuffman:
-                    optionG32D = false;
-                    break;
-                case CcittFaxCompressionType.T4:
-                    optionG32D = true;
-                    break;
-                case CcittFaxCompressionType.T6:
-                    optionG32D = false;
-                    break;
-                default:
-                    throw new ArgumentOutOfRangeException(nameof(type), type, "Illegal parameter");
-            }
         }
 
         private void Fetch()
@@ -252,7 +237,7 @@
             }
 
         done:
-            if (!optionG32D || ReadBit())
+            if (type == CcittFaxCompressionType.Group3_1D || ReadBit())
             {
                 Decode1D();
             }
@@ -279,10 +264,11 @@
                 case CcittFaxCompressionType.ModifiedHuffman:
                     DecodeRowType2();
                     break;
-                case CcittFaxCompressionType.T4:
+                case CcittFaxCompressionType.Group3_1D:
+                case CcittFaxCompressionType.Group3_2D:
                     DecodeRowType4();
                     break;
-                case CcittFaxCompressionType.T6:
+                case CcittFaxCompressionType.Group4_2D:
                     DecodeRowType6();
                     break;
                 default: