diff --git a/vncviewer/CConn.cxx b/vncviewer/CConn.cxx
index e295c34..5b5be99 100644
--- a/vncviewer/CConn.cxx
+++ b/vncviewer/CConn.cxx
@@ -50,9 +50,14 @@
 
 static rfb::LogWriter vlog("CConn");
 
-static const PixelFormat mediumColourPF(8,3,0,1,1,1,1,2,1,0);
-static const PixelFormat lowColourPF(8,6,0,1,3,3,3,4,2,0);
-static const PixelFormat verylowColourPF(8,8,0,0);
+// 8 colours (1 bit per component)
+static const PixelFormat verylowColourPF(8, 3,false, true,
+                                         1, 1, 1, 2, 1, 0);
+// 64 colours (2 bits per component)
+static const PixelFormat lowColourPF(8, 6, false, true,
+                                     3, 3, 3, 4, 2, 0);
+// 256 colours (palette)
+static const PixelFormat mediumColourPF(8, 8, false, false);
 
 CConn::CConn(const char* vncServerName)
   : serverHost(0), serverPort(0), sock(NULL), desktop(NULL),
@@ -503,11 +508,11 @@
       pf = fullColourPF;
     } else {
       if (lowColourLevel == 0)
-        pf = mediumColourPF;
+        pf = verylowColourPF;
       else if (lowColourLevel == 1)
         pf = lowColourPF;
       else
-        pf = verylowColourPF;
+        pf = mediumColourPF;
     }
     char str[256];
     pf.print(str, 256);
@@ -564,11 +569,11 @@
     pf = self->fullColourPF;
   } else {
     if (lowColourLevel == 0)
-      pf = mediumColourPF;
+      pf = verylowColourPF;
     else if (lowColourLevel == 1)
       pf = lowColourPF;
     else
-      pf = verylowColourPF;
+      pf = mediumColourPF;
   }
 
   if (!pf.equal(self->cp.pf()))
diff --git a/vncviewer/OptionsDialog.cxx b/vncviewer/OptionsDialog.cxx
index d3928b5..191a311 100644
--- a/vncviewer/OptionsDialog.cxx
+++ b/vncviewer/OptionsDialog.cxx
@@ -150,13 +150,13 @@
   else {
     switch (lowColourLevel) {
     case 0:
-      mediumcolorCheckbox->setonly();
+      verylowcolorCheckbox->setonly();
       break;
     case 1:
       lowcolorCheckbox->setonly();
       break;
     case 2:
-      verylowcolorCheckbox->setonly();
+      mediumcolorCheckbox->setonly();
       break;
     }
   }
@@ -292,11 +292,11 @@
     preferredEncoding.setParam(encodingName(encodingRaw));
 
   fullColour.setParam(fullcolorCheckbox->value());
-  if (mediumcolorCheckbox->value())
+  if (verylowcolorCheckbox->value())
     lowColourLevel.setParam(0);
   else if (lowcolorCheckbox->value())
     lowColourLevel.setParam(1);
-  else if (verylowcolorCheckbox->value())
+  else if (mediumcolorCheckbox->value())
     lowColourLevel.setParam(2);
 
   customCompressLevel.setParam(compressionCheckbox->value());