diff --git a/ChangeLog b/ChangeLog
index c782791c..9c0e8b52 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-12-13  Lee Howard <faxguy@howardsilvan.com>
+
+	* libtiff/tif_jpeg.c: reduce usage of JCS_UNKNOWN in order
+	to improve compatibility with various viewers
+	submitted by e-mail from Dwight Kelly <dkelly@apago.com>
+
 2010-12-13  Lee Howard <faxguy@howardsilvan.com>
 
 	* tools/fax2ps.c: be consistent with page-numbering
diff --git a/libtiff/tif_jpeg.c b/libtiff/tif_jpeg.c
index dcf6709e..400f7da7 100644
--- a/libtiff/tif_jpeg.c
+++ b/libtiff/tif_jpeg.c
@@ -1,4 +1,4 @@
-/* $Id: tif_jpeg.c,v 1.95 2010-12-12 01:55:00 faxguy Exp $ */
+/* $Id: tif_jpeg.c,v 1.96 2010-12-14 23:58:39 faxguy Exp $ */
 
 /*
  * Copyright (c) 1994-1997 Sam Leffler
@@ -1701,8 +1701,15 @@ JPEGPreEncode(TIFF* tif, uint16 s)
 			sp->cinfo.c.comp_info[0].h_samp_factor = sp->h_sampling;
 			sp->cinfo.c.comp_info[0].v_samp_factor = sp->v_sampling;
 		} else {
-			sp->cinfo.c.in_color_space = JCS_UNKNOWN;
-			if (!TIFFjpeg_set_colorspace(sp, JCS_UNKNOWN))
+			if (td->td_photometric == PHOTOMETRIC_MINISWHITE || td->td_photometric == PHOTOMETRIC_MINISBLACK)
+				sp->cinfo.c.in_color_space = JCS_GRAYSCALE;
+			else if (td->td_photometric == PHOTOMETRIC_RGB)
+				sp->cinfo.c.in_color_space = JCS_RGB;
+			else if (td->td_photometric == PHOTOMETRIC_SEPARATED && td->td_samplesperpixel == 4)
+				sp->cinfo.c.in_color_space = JCS_CMYK;
+			else
+				sp->cinfo.c.in_color_space = JCS_UNKNOWN;
+			if (!TIFFjpeg_set_colorspace(sp, (sp->cinfo.c.in_color_space == JCS_RGB) ? JCS_YCbCr : sp->cinfo.c.in_color_space))
 				return (0);
 			/* jpeg_set_colorspace set all sampling factors to 1 */
 		}