--- poppler-0.17.1-cmyk-to-gray/poppler/PSOutputDev.cc-	2011-05-30 12:00:42.199995904 -0300
+++ poppler-0.17.1-cmyk-to-gray/poppler/PSOutputDev.cc	2011-05-30 12:23:40.878191236 -0300
@@ -2986,6 +2986,7 @@
   GfxState *state;
   SplashBitmap *bitmap;
   Stream *str0, *str;
+  Stream *str1 = NULL;
   Object obj;
   Guchar *p;
   Guchar col[4];
@@ -2995,6 +2996,8 @@
   char hexBuf[32*2 + 2];	// 32 values X 2 chars/value + line ending + null
   Guchar digit;
   GBool useBinary;
+  GBool isGray;
+  int compCyan;
 
   if (!forceRasterize) {
     scan = new PreScanOutputDev(xref);
@@ -3225,15 +3228,35 @@
   case psLevel3Sep:
     obj.initNull();
     str0 = new MemStream((char *)bitmap->getDataPtr(), 0, w * h * 4, &obj);
-    processColors |= psProcessCMYK;
-    writePS("/DeviceCMYK setcolorspace\n");
-    str = new RunLengthEncoder(str0);
+    isGray = gTrue;
+    while ((compCyan = str0->getChar()) != EOF) {
+      if (str0->getChar() != compCyan ||
+          str0->getChar() != compCyan) {
+	isGray = gFalse;
+	break;
+      }
+      str0->getChar();
+    }
+    str0->reset();
+    if (isGray) {
+      writePS("/DeviceGray setcolorspace\n");
+      str1 = new CMKYGrayEncoder(str0);
+      str = new RunLengthEncoder(str1);
+    } else {
+      processColors |= psProcessCMYK;
+      writePS("/DeviceCMYK setcolorspace\n");
+      str = new RunLengthEncoder(str0);
+    }
     writePS("<<\n  /ImageType 1\n");
     writePSFmt("  /Width {0:d}\n", bitmap->getWidth());
     writePSFmt("  /Height {0:d}\n", bitmap->getHeight());
     writePSFmt("  /ImageMatrix [{0:d} 0 0 {1:d} 0 {2:d}]\n", w, -h, h);
     writePS("  /BitsPerComponent 8\n");
-    writePS("  /Decode [0 1 0 1 0 1 0 1]\n");
+    if (isGray) {
+      writePS("  /Decode [1 0]\n");
+    } else {
+      writePS("  /Decode [0 1 0 1 0 1 0 1]\n");
+    }
     writePS("  /DataSource currentfile\n");
     useBinary = globalParams->getPSBinary();
     if (useBinary) {
@@ -3267,9 +3290,12 @@
     }
     if (useBinary) {
       writePS("\n%%EndData\n");
+    } else if (isGray) {
+      writePSChar('\n');
     }
     str->close();
     delete str;
+    // delete str1; // deleted by str0
     delete str0;
     break;
   case psLevel2:
--- poppler-0.17.1-cmyk-to-gray/poppler/Stream.cc-	2010-11-08 17:45:24.000000000 -0300
+++ poppler-0.17.1-cmyk-to-gray/poppler/Stream.cc	2011-05-30 12:23:40.882191172 -0300
@@ -4923,3 +4923,46 @@
   bufPtr = buf;
   return gTrue;
 }
+
+//------------------------------------------------------------------------
+// CMKYGrayEncoder
+//------------------------------------------------------------------------
+
+CMKYGrayEncoder::CMKYGrayEncoder(Stream *strA):
+    FilterStream(strA) {
+  bufPtr = bufEnd = buf;
+  eof = gFalse;
+}
+
+CMKYGrayEncoder::~CMKYGrayEncoder() {
+  if (str->isEncoder())
+    delete str;
+}
+
+void CMKYGrayEncoder::reset() {
+  str->reset();
+  bufPtr = bufEnd = buf;
+  eof = gFalse;
+}
+
+GBool CMKYGrayEncoder::fillBuf() {
+  int c0, c1, c2, c3;
+  int i;
+
+  if (eof) {
+    return gFalse;
+  }
+  c0 = str->getChar();
+  c1 = str->getChar();
+  c2 = str->getChar();
+  c3 = str->getChar();
+  if (c3 == EOF) {
+    eof = gTrue;
+    return gFalse;
+  }
+  i = (3 * c0 + 6 * c1 + c2) / 10 + c3;
+  if (i > 255) i = 255;
+  bufPtr = bufEnd = buf;
+  *bufEnd++ = (char) i;
+  return gTrue;
+}
--- poppler-0.17.1-cmyk-to-gray/poppler/Stream.h-	2010-11-10 20:08:18.000000000 -0300
+++ poppler-0.17.1-cmyk-to-gray/poppler/Stream.h	2011-05-30 12:23:40.883191150 -0300
@@ -1141,4 +1141,33 @@
   GBool fillBuf();
 };
 
+//------------------------------------------------------------------------
+// CMKYGrayEncoder
+//------------------------------------------------------------------------
+
+class CMKYGrayEncoder: public FilterStream {
+public:
+
+  CMKYGrayEncoder(Stream *strA);
+  virtual ~CMKYGrayEncoder();
+  virtual StreamKind getKind() { return strWeird; }
+  virtual void reset();
+  virtual int getChar()
+    { return (bufPtr >= bufEnd && !fillBuf()) ? EOF : (*bufPtr++ & 0xff); }
+  virtual int lookChar()
+    { return (bufPtr >= bufEnd && !fillBuf()) ? EOF : (*bufPtr & 0xff); }
+  virtual GooString *getPSFilter(int /*psLevel*/, char * /*indent*/) { return NULL; }
+  virtual GBool isBinary(GBool /*last = gTrue*/) { return gFalse; }
+  virtual GBool isEncoder() { return gTrue; }
+
+private:
+
+  char buf[2];
+  char *bufPtr;
+  char *bufEnd;
+  GBool eof;
+
+  GBool fillBuf();
+};
+
 #endif