add "rgbjpeg" flag to tiffsave

add a secret "rgbjpeg" flag to tiffsave to help IIPImage server

iipimage server 0.9.9 and earlier don't handle YCbCr-coded JPEG tiffs
correctly ... setting --rgbjpeg makes vips output RGB coded JPEG tiff
which iipsrv can handle.

Using this flag makes files 2x to 3x larger with no quality improvement,
so it is tagged as deprecated to keep it hidden.

ChangeLog

@@ -4,6 +4,7 @@
 - foreign memory buffer images did not have the right dhint, broke
   command-line falsecolour on sequential images
 - support many Radiance readers active at once
+- add secret "rgbjpeg" flag to vips_tiffsave() to help IIP
 
 19/1/14 started 7.38.1
 - bump soname, thanks benjamin

libvips/foreign/tiff.h

@@ -47,7 +47,8 @@ int vips__tiff_write( VipsImage *in, const char *filename,
 	gboolean pyramid,
 	gboolean squash,
 	VipsForeignTiffResunit resunit, double xres, double yres,
-	gboolean bigtiff );
+	gboolean bigtiff,
+	gboolean rgbjpeg );
 
 int vips__tiff_read( const char *filename, VipsImage *out, int page, 
 	gboolean readbehind );

libvips/foreign/tiffsave.c

@@ -4,6 +4,8 @@
  * 	- wrap a class around the tiff writer
  * 17/3/12
  * 	- argh xres/yres macro was wrong
+ * 26/1/14
+ * 	- add rgbjpeg flag
  */
 
 /*
@@ -75,6 +77,7 @@ typedef struct _VipsForeignSaveTiff {
 	double xres;
 	double yres;
 	gboolean bigtiff;
+	gboolean rgbjpeg;
 } VipsForeignSaveTiff;
 
 typedef VipsForeignSaveClass VipsForeignSaveTiffClass;
@@ -123,7 +126,8 @@ vips_foreign_save_tiff_build( VipsObject *object )
 		tiff->pyramid,
 		tiff->squash,
 		tiff->resunit, tiff->xres, tiff->yres,
-		tiff->bigtiff ) )
+		tiff->bigtiff,
+		tiff->rgbjpeg ) )
 		return( -1 );
 
 	return( 0 );
@@ -249,6 +253,13 @@ vips_foreign_save_tiff_class_init( VipsForeignSaveTiffClass *class )
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignSaveTiff, bigtiff ),
 		FALSE );
+
+	VIPS_ARG_BOOL( class, "rgbjpeg", 20, 
+		_( "RGB JPEG" ),
+		_( "Output RGB JPEG rather than YCbCr" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED, 
+		G_STRUCT_OFFSET( VipsForeignSaveTiff, rgbjpeg ),
+		FALSE );
 }
 
 static void

libvips/foreign/vips2tiff.c

@@ -136,6 +136,8 @@
  * 24/9/13
  * 	- support many more vips formats, eg. complex, 32-bit int, any number
  * 	  of bands, etc., see the tiff loader
+ * 26/1/14
+ * 	- add RGB as well as YCbCr write
  */
 
 /*
@@ -261,6 +263,7 @@ typedef struct tiff_write {
         float yres;                    	/* Resolution in Y */
 	char *icc_profile;		/* Profile to embed */
 	int bigtiff;			/* True for bigtiff write */
+	int rgbjpeg;			/* True for RGB not YCbCr */
 
 	GMutex *write_lock;		/* Lock TIFF*() calls with this */
 } TiffWrite;
@@ -529,7 +532,8 @@ write_tiff_header( TiffWrite *tw, TIFF *tif, int width, int height )
 			}
 			else if( tw->compression == COMPRESSION_JPEG &&
 				tw->im->Bands == 3 &&
-				tw->im->BandFmt == VIPS_FORMAT_UCHAR ) { 
+				tw->im->BandFmt == VIPS_FORMAT_UCHAR &&
+				!tw->rgbjpeg ) { 
 				/* This signals to libjpeg that it can do
 				 * YCbCr chrominance subsampling from RGB, not
 				 * that we will supply the image as YCbCr.
@@ -1291,7 +1295,8 @@ make_tiff_write( VipsImage *im, const char *filename,
 	gboolean pyramid,
 	gboolean squash,
 	VipsForeignTiffResunit resunit, double xres, double yres,
-	gboolean bigtiff )
+	gboolean bigtiff,
+	gboolean rgbjpeg )
 {
 	TiffWrite *tw;
 
@@ -1313,6 +1318,7 @@ make_tiff_write( VipsImage *im, const char *filename,
 	tw->onebit = squash;
 	tw->icc_profile = profile;
 	tw->bigtiff = bigtiff;
+	tw->rgbjpeg = rgbjpeg;
 	tw->write_lock = NULL;
 
 	tw->resunit = get_resunit( resunit );
@@ -1531,7 +1537,8 @@ vips__tiff_write( VipsImage *in, const char *filename,
 	gboolean pyramid,
 	gboolean squash,
 	VipsForeignTiffResunit resunit, double xres, double yres,
-	gboolean bigtiff )
+	gboolean bigtiff,
+	gboolean rgbjpeg )
 {
 	TiffWrite *tw;
 	int res;
@@ -1553,7 +1560,7 @@ vips__tiff_write( VipsImage *in, const char *filename,
 	if( !(tw = make_tiff_write( in, filename,
 		compression, Q, predictor, profile,
 		tile, tile_width, tile_height, pyramid, squash,
-		resunit, xres, yres, bigtiff )) )
+		resunit, xres, yres, bigtiff, rgbjpeg )) )
 		return( -1 );
 	if( tw->pyramid ) {
 		if( !(tw->bname = vips__temp_name( "%s.tif" )) ||