diff --git a/utils/HtmlOutputDev.cc b/utils/HtmlOutputDev.cc
index 17541a2..22f2b9a 100644
--- a/utils/HtmlOutputDev.cc
+++ b/utils/HtmlOutputDev.cc
@@ -1322,7 +1322,80 @@ void HtmlOutputDev::drawImageMask(GfxState *state, Object *ref, Stream *str,
     drawJpegImage(state, str);
   }
   else {
-    OutputDev::drawImageMask(state, ref, str, width, height, invert, interpolate, inlineImg);
+#ifdef ENABLE_LIBPNG
+    FILE *f1;
+    GooString *fName=new GooString(Docname);
+    fName->append("-");
+    GooString *pgNum= GooString::fromInt(pageNum);
+    GooString *imgnum= GooString::fromInt(pages->getNumImages()+1);
+
+    // open the image file
+    fName->append(pgNum)->append("_")->append(imgnum)->append(".png");
+    delete pgNum;
+    delete imgnum;
+
+    if (!(f1 = fopen(fName->getCString(), "wb"))) {
+      error(errIO, -1, "Couldn't open image file '%s'", fName->getCString());
+      delete fName;
+      return;
+    }
+
+    PNGWriter *writer = new PNGWriter( PNGWriter::MONOCHROME );
+    if (!writer->init(f1, width, height, 72, 72)) {
+      error(errInternal, -1, "Can't init PNG for image '%s'", fName->getCString());
+      delete writer;
+      fclose(f1);
+      return;
+    }
+
+    int bytes_per_row = ((width + 7) / 8);
+    Guchar *bit_row = (Guchar *)gmalloc( bytes_per_row );
+    Guchar *png_row = (Guchar *)gmalloc( width );
+
+    str->reset();
+    for (int ri = 0; ri < height; ++ri)
+    {
+      // read the row bits of the mask
+      for (int i = 0; i < bytes_per_row; ++i) {
+        if ((bit_row[i] = str->getChar()) != EOF) {
+        } else {
+          error(errIO, -1, "Image mask stream is corrupt for image '%s'", fName->getCString());
+          delete writer;
+          fclose(f1);
+          gfree(bit_row);
+          gfree(png_row);
+          return;
+        }
+      }
+
+      // convert bits into a bytes for PNG
+      for(int i = 0; i < width; i++)
+        png_row[i] = ((bit_row[i/8]) & (1<<(7-(i%8)))) ? 0x00 : 0xff ; // invert for PNG
+
+      if (!writer->writeRow( &png_row ))
+      {
+        error(errIO, -1, "Failed to write into PNG '%s'", fName->getCString());
+        delete writer;
+        fclose(f1);
+        gfree(bit_row);
+        gfree(png_row);
+        return;
+      }
+    }
+    str->close();
+
+    writer->close();
+    delete writer;
+    fclose(f1);
+
+    gfree(bit_row);
+    gfree(png_row);
+
+    pages->addImage(fName, state);
+#else
+    OutputDev::drawImage(state, ref, str, width, height, colorMap, interpolate,
+			 maskColors, inlineImg);
+#endif
   }
 }