Update ByteExtensions.cs

Original implementation didn't work for bit-length of 4

Former-commit-id: bc96d70df88c933fc10b815a9b08327bbdae5461
Former-commit-id: 2678a00b2afc86526cffd3bb68d6bb5be1652a92
Former-commit-id: d64de4730e2465cb9e89c1d7c673ca86d2893523

src/ImageProcessorCore/Common/Extensions/ByteExtensions.cs

@@ -32,7 +32,8 @@ namespace ImageProcessorCore
             {
                 result = new byte[bytes.Length * 8 / bits];
 
-                int factor = (int)Math.Pow(2, bits) - 1;
+                // BUGFIX I dont think it should be there, but I am not sure if it breaks something else
+                //int factor = (int)Math.Pow(2, bits) - 1;
                 int mask = 0xFF >> (8 - bits);
                 int resultOffset = 0;
 
@@ -40,7 +41,7 @@ namespace ImageProcessorCore
                 {
                     for (int shift = 0; shift < 8; shift += bits)
                     {
-                        int colorIndex = ((b >> (8 - bits - shift)) & mask) * (255 / factor);
+                        int colorIndex = ((b >> (8 - bits - shift)) & mask); // * (255 / factor);
 
                         result[resultOffset] = (byte)colorIndex;