diff -ur Imaging-1.1.6-orig/PIL/JpegImagePlugin.py Imaging-1.1.6/PIL/JpegImagePlugin.py
--- Imaging-1.1.6-orig/PIL/JpegImagePlugin.py	2006-12-03 03:37:15.000000000 -0800
+++ Imaging-1.1.6/PIL/JpegImagePlugin.py	2008-01-30 08:48:28.707703071 -0800
@@ -403,7 +403,8 @@
         info.get("smooth", 0),
         info.has_key("optimize"),
         info.get("streamtype", 0),
-        dpi[0], dpi[1]
+        dpi[0], dpi[1],
+        info.get("subsampling", -1)
         )
 
     ImageFile._save(im, fp, [("jpeg", (0,0)+im.size, 0, rawmode)])
diff -ur Imaging-1.1.6-orig/encode.c Imaging-1.1.6/encode.c
--- Imaging-1.1.6-orig/encode.c	2006-12-03 03:51:25.000000000 -0800
+++ Imaging-1.1.6/encode.c	2008-01-31 11:35:48.124779643 -0800
@@ -503,9 +503,10 @@
     int optimize = 0;
     int streamtype = 0; /* 0=interchange, 1=tables only, 2=image only */
     int xdpi = 0, ydpi = 0;
-    if (!PyArg_ParseTuple(args, "ss|iiiiiii", &mode, &rawmode, &quality,
+	int subsampling = -1; /* -1=default, 0=none, 1=medium, 2=high */
+    if (!PyArg_ParseTuple(args, "ss|iiiiiiii", &mode, &rawmode, &quality,
 			  &progressive, &smooth, &optimize, &streamtype,
-                          &xdpi, &ydpi))
+                          &xdpi, &ydpi, &subsampling))
 	return NULL;
 
     encoder = PyImaging_EncoderNew(sizeof(JPEGENCODERSTATE));
@@ -518,6 +519,7 @@
     encoder->encode = ImagingJpegEncode;
 
     ((JPEGENCODERSTATE*)encoder->state.context)->quality = quality;
+    ((JPEGENCODERSTATE*)encoder->state.context)->subsampling = subsampling;
     ((JPEGENCODERSTATE*)encoder->state.context)->progressive = progressive;
     ((JPEGENCODERSTATE*)encoder->state.context)->smooth = smooth;
     ((JPEGENCODERSTATE*)encoder->state.context)->optimize = optimize;
diff -ur Imaging-1.1.6-orig/libImaging/Jpeg.h Imaging-1.1.6/libImaging/Jpeg.h
--- Imaging-1.1.6-orig/libImaging/Jpeg.h	2006-12-03 03:37:25.000000000 -0800
+++ Imaging-1.1.6/libImaging/Jpeg.h	2008-01-30 08:48:19.611543368 -0800
@@ -85,6 +85,9 @@
     /* DPI setting (0=square pixels, otherwide DPI) */
     int xdpi, ydpi;
 
+	/*Chroma Subsampling (-1=default, 0=none, 1=medium, 2=high) */
+	int subsampling;
+
     /* PRIVATE CONTEXT (set by encoder) */
 
     struct jpeg_compress_struct cinfo;
diff -ur Imaging-1.1.6-orig/libImaging/JpegEncode.c Imaging-1.1.6/libImaging/JpegEncode.c
--- Imaging-1.1.6-orig/libImaging/JpegEncode.c	2006-12-03 03:37:25.000000000 -0800
+++ Imaging-1.1.6/libImaging/JpegEncode.c	2008-01-31 11:39:40.763673088 -0800
@@ -143,6 +143,46 @@
 	jpeg_set_defaults(&context->cinfo);
 	if (context->quality > 0)
 	    jpeg_set_quality(&context->cinfo, context->quality, 1);
+	
+	/* Set subsampling options */
+	switch (context->subsampling)
+	{
+		case 0:  /* 1x1 1x1 1x1 (4:4:4) : None */
+		{
+			context->cinfo.comp_info[0].h_samp_factor = 1;
+			context->cinfo.comp_info[0].v_samp_factor = 1;
+			context->cinfo.comp_info[1].h_samp_factor = 1;
+			context->cinfo.comp_info[1].v_samp_factor = 1;
+			context->cinfo.comp_info[2].h_samp_factor = 1;
+			context->cinfo.comp_info[2].v_samp_factor = 1;
+			break;
+		}
+		case 1:  /* 2x1, 1x1, 1x1 (4:2:2) : Medium */
+		{
+			context->cinfo.comp_info[0].h_samp_factor = 2;
+			context->cinfo.comp_info[0].v_samp_factor = 1;
+			context->cinfo.comp_info[1].h_samp_factor = 1;
+			context->cinfo.comp_info[1].v_samp_factor = 1;
+			context->cinfo.comp_info[2].h_samp_factor = 1;
+			context->cinfo.comp_info[2].v_samp_factor = 1;
+			break;
+		}
+		case 2:  /* 2x2, 1x1, 1x1 (4:1:1) : High */
+		{
+			context->cinfo.comp_info[0].h_samp_factor = 2;
+			context->cinfo.comp_info[0].v_samp_factor = 2;
+			context->cinfo.comp_info[1].h_samp_factor = 1;
+			context->cinfo.comp_info[1].v_samp_factor = 1;
+			context->cinfo.comp_info[2].h_samp_factor = 1;
+			context->cinfo.comp_info[2].v_samp_factor = 1;
+			break;
+		}
+		default:
+		{
+			/* Use the lib's default */
+			break;
+		}
+	}
 	if (context->progressive)
 	    jpeg_simple_progression(&context->cinfo);
 	context->cinfo.smoothing_factor = context->smooth;