cmyk jpeg write

ChangeLog

@@ -5,6 +5,8 @@
 - revert the dynamic wrapping for Python :-( next version!
 - added VImage::convert2disc (thanks Ole)
 - you can now set the jpeg quality factor for tiff pyramids (thanks Joe)
+- you can now shrink jpegs during read, see "man im_jpeg2vips"
+- added CMYK JPEG write
 
 12/12/07 started 7.13.3
 - added "include <cstring>" to VImage.cc to help gcc 4.3

TODO

@@ -1,17 +1,9 @@
 - JPEG write should know about CMYK as well, maybe write all 4 band images as
   CMYK?
 
-- JPEG read could have a "subsample" param and use 
-
-unsigned int scale_num, scale_denom 
-	Scale the image by the fraction scale_num/scale_denom.
-	Default is 1/1, or no scaling.	Currently, the only supported
-	scaling ratios are 1/1, 1/2, 1/4, and 1/8.  (The library design
-	allows for arbitrary scaling ratios but this is not likely to
-	be implemented any time soon.)	Smaller scaling ratios permit
-	significantly faster decoding since fewer pixels need be processed
-	and a simpler IDCT method can be used.
+  test CMYK JPEG write, also PNG write with new saveable
 
+  can we use convert_saveable for PPM and friends as well?
 
 - HAVE_HYPOT could define a hypot() macro?
 

include/vips/internal.h

@@ -77,7 +77,13 @@ extern int im__read_test;
 extern int im__mmap_limit;
 extern GMutex *im__global_lock;
 
-IMAGE *im__convert_saveable( IMAGE *in, gboolean allow_alpha );
+typedef enum {
+	IM__RGB,	/* 1 or 3 bands (like PPM) */
+	IM__RGBA,	/* 1, 2, 3 or 4 bands (like PNG) */
+	IM__RGB_CMYK	/* 1, 3 or 4 bands (like JPEG) */
+} im__saveable_t;
+
+IMAGE *im__convert_saveable( IMAGE *in, im__saveable_t saveable );
 
 void im__link_make( IMAGE *parent, IMAGE *child );
 void im__link_break_all( IMAGE *im );

libsrc/conversion/im_copy.c

@@ -52,6 +52,8 @@
  * 2/11/06
  * 	- moved im__convert_saveable() here so it's always defined (was part
  * 	  of JPEG write code)
+ * 15/2/08
+ * 	- added im__saveable_t ... so we can have CMYK JPEG write
  */
 
 /*
@@ -90,6 +92,7 @@
 #include <math.h>
 
 #include <vips/vips.h>
+#include <vips/internal.h>
 
 #ifdef WITH_DMALLOC
 #include <dmalloc.h>
@@ -344,11 +347,12 @@ im_copy_from( IMAGE *in, IMAGE *out, im_arch_type architecture )
 	}
 }
 
-/* Convert to 1 or 3 band uchar sRGB (or 2/4 band, if allow_alpha is set). 
- * Need to im_close() the return IMAGE.
+/* Convert to a saveable format. im__saveable_t gives the general type of image
+ * we make: vanilla 1/3 bands (PPM), with an optional alpha (like PNG), or
+ * with CMYK as an option (like JPEG). Need to im_close() the return IMAGE.
  */
 IMAGE *
-im__convert_saveable( IMAGE *in, gboolean allow_alpha )
+im__convert_saveable( IMAGE *in, im__saveable_t saveable )
 {
 	IMAGE *out;
 
@@ -375,11 +379,10 @@ im__convert_saveable( IMAGE *in, gboolean allow_alpha )
 		in = t;
 	}
 
-	/* Get the bands right. If we have >3, drop down to 3. If we have 2,
-	 * drop down to 1. If allow_alpha is on, we can also have 2/4 bands.
+	/* Get the bands right. 
 	 */
 	if( in->Coding == IM_CODING_NONE ) {
-		if( in->Bands == 2  && !allow_alpha ) {
+		if( in->Bands == 2 && saveable != IM__RGBA ) {
 			IMAGE *t = im_open_local( out, "conv:1", "p" );
 
 			if( !t || im_extract_band( in, t, 0 ) ) {
@@ -389,7 +392,7 @@ im__convert_saveable( IMAGE *in, gboolean allow_alpha )
 
 			in = t;
 		}
-		else if( in->Bands > 3 && !allow_alpha ) {
+		else if( in->Bands > 3 && saveable == IM__RGB ) {
 			IMAGE *t = im_open_local( out, "conv:1", "p" );
 
 			if( !t ||
@@ -400,7 +403,8 @@ im__convert_saveable( IMAGE *in, gboolean allow_alpha )
 
 			in = t;
 		}
-		else if( in->Bands > 4 && allow_alpha ) {
+		else if( in->Bands > 4 && 
+			(saveable == IM__RGB_CMYK || saveable == IM__RGBA) ) {
 			IMAGE *t = im_open_local( out, "conv:1", "p" );
 
 			if( !t ||

libsrc/conversion/im_jpeg2vips.c

@@ -20,6 +20,8 @@
  * 11/2/08
  * 	- spot CMYK jpegs and set Type
  * 	- spot Adobe CMYK JPEG and invert ink density
+ * 15/2/08
+ * 	- added "shrink" parameter
  */
 
 /*
@@ -432,7 +434,7 @@ read_exif( IMAGE *im, void *data, int data_length )
  */
 static int
 read_jpeg_header( struct jpeg_decompress_struct *cinfo, 
-	IMAGE *out, gboolean *invert_pels )
+	IMAGE *out, gboolean *invert_pels, int shrink )
 {
 	jpeg_saved_marker_ptr p;
 	int type;
@@ -448,6 +450,7 @@ read_jpeg_header( struct jpeg_decompress_struct *cinfo,
 	 * for YUV YCCK etc.
 	 */
 	jpeg_read_header( cinfo, TRUE );
+	cinfo->scale_denom = shrink;
 	jpeg_calc_output_dimensions( cinfo );
 	*invert_pels = FALSE;
 	switch( cinfo->out_color_space ) {
@@ -611,12 +614,32 @@ read_jpeg_image( struct jpeg_decompress_struct *cinfo, IMAGE *out,
 static int
 jpeg2vips( const char *name, IMAGE *out, gboolean header_only )
 {
+	char filename[FILENAME_MAX];
+	char mode[FILENAME_MAX];
+	char *p, *q;
+	int shrink;
 	struct jpeg_decompress_struct cinfo;
         ErrorManager eman;
 	FILE *fp;
 	int result;
 	gboolean invert_pels;
 
+	/* Parse the filename.
+	 */
+	im_filename_split( name, filename, mode );
+	p = &mode[0];
+	shrink = 1;
+	if( (q = im_getnextoption( &p )) ) {
+		shrink = atoi( q );
+
+		if( shrink != 1 && shrink != 2 && 
+			shrink != 4 && shrink != 8 ) {
+			im_error( "im_jpeg2vips", 
+				_( "bad shrink factor %d" ), shrink );
+			return( -1 );
+		}
+	}
+
 	/* Make jpeg compression object.
  	 */
         cinfo.err = jpeg_std_error( &eman.pub );
@@ -635,12 +658,13 @@ jpeg2vips( const char *name, IMAGE *out, gboolean header_only )
 	/* Make input.
 	 */
 #ifdef BINARY_OPEN
-        if( !(fp = fopen( name, "rb" )) ) {
+        if( !(fp = fopen( filename, "rb" )) ) {
 #else /*BINARY_OPEN*/
-        if( !(fp = fopen( name, "r" )) ) {
+        if( !(fp = fopen( filename, "r" )) ) {
 #endif /*BINARY_OPEN*/
 		jpeg_destroy_decompress( &cinfo );
-                im_error( "im_jpeg2vips", _( "unable to open \"%s\"" ), name );
+                im_error( "im_jpeg2vips", 
+			_( "unable to open \"%s\"" ), filename );
 
                 return( -1 );
         }
@@ -654,7 +678,7 @@ jpeg2vips( const char *name, IMAGE *out, gboolean header_only )
 
 	/* Convert!
 	 */
-	result = read_jpeg_header( &cinfo, out, &invert_pels );
+	result = read_jpeg_header( &cinfo, out, &invert_pels, shrink );
 	if( !header_only && !result )
 		result = read_jpeg_image( &cinfo, out, invert_pels );
 

libsrc/conversion/im_vips2jpeg.c

@@ -1,4 +1,4 @@
-/* Convert 1 or 3-band 8-bit VIPS images to/from JPEG.
+/* Convert 8-bit VIPS images to/from JPEG.
  *
  * 28/11/03 JC
  *	- better no-overshoot on tile loop
@@ -23,6 +23,8 @@
  * 	- oop, libexif confusion
  * 2/11/07
  * 	- use im_wbuffer() API for BG writes
+ * 15/2/08
+ * 	- write CMYK if Bands == 4 and Type == CMYK
  */
 
 /*
@@ -217,9 +219,9 @@ write_new( IMAGE *in )
 		return( NULL );
 	memset( write, 0, sizeof( Write ) );
 
-	if( !(write->in = im__convert_saveable( in, FALSE )) ) {
+	if( !(write->in = im__convert_saveable( in, IM__RGB_CMYK )) ) {
 		im_error( "im_vips2jpeg", 
-			_( "unable to convert to RGB for save" ) );
+			_( "unable to convert to saveable format" ) );
 		write_destroy( write );
 		return( NULL );
 	}
@@ -541,12 +543,13 @@ static int
 write_vips( Write *write, int qfac, const char *profile )
 {
 	IMAGE *in = write->in;
+	J_COLOR_SPACE space;
 
 	/* Should have been converted for save.
 	 */
         assert( in->BandFmt == IM_BANDFMT_UCHAR );
 	assert( in->Coding == IM_CODING_NONE );
-        assert( in->Bands == 1 || in->Bands == 3 );
+        assert( in->Bands == 1 || in->Bands == 3 || in->Bands == 4 );
 
         /* Check input image.
          */
@@ -561,14 +564,18 @@ write_vips( Write *write, int qfac, const char *profile )
 	 */
         write->cinfo.image_width = in->Xsize;
         write->cinfo.image_height = in->Ysize;
-	if( in->Bands == 3 ) {
-		write->cinfo.input_components = 3;
-		write->cinfo.in_color_space = JCS_RGB; 
-	}
-	else if( in->Bands == 1 ) {
-		write->cinfo.input_components = 1;
-		write->cinfo.in_color_space = JCS_GRAYSCALE; 
-	}
+	write->cinfo.input_components = in->Bands;
+	if( in->Bands == 4 && in->Type == IM_TYPE_CMYK )
+		space = JCS_CMYK;
+	else if( in->Bands == 3 )
+		space = JCS_RGB;
+	else if( in->Bands == 1 )
+		space = JCS_GRAYSCALE;
+	else 
+		/* Use luminance compression for all channels.
+		 */
+		space = JCS_UNKNOWN;
+	write->cinfo.in_color_space = space; 
 
 	/* Rest to default. 
 	 */

libsrc/conversion/im_vips2png.c

@@ -125,7 +125,7 @@ write_new( IMAGE *in )
 		return( NULL );
 	memset( write, 0, sizeof( Write ) );
 
-	if( !(write->in = im__convert_saveable( in, TRUE )) ) {
+	if( !(write->in = im__convert_saveable( in, IM__RGBA )) ) {
 		im_error( "im_vips2png", 
 			_( "unable to convert to RGB for save" ) );
 		write_destroy( write );

man/im_jpeg2vips.3

@@ -17,8 +17,21 @@ int im_vips2mimejpeg( IMAGE *in )
 .SH DESCRIPTION
 .B im_jpeg2vips() 
 reads the named jpeg file and writes it to the specified
-IMAGE. The entire image is read before returning. It will handle 1 and 3 band
-8-bit images only.
+IMAGE. The entire image is read before returning. It can read most 8-bit JPEG
+images, including CMYK. 
+
+You can embed options in the filename. They have the form:
+
+  filename.jpg:<shrink-factor>
+
+.B shrink-factor 
+will shrink the image by that factor during read. Allowed values are 1, 2, 4
+and 8. Shrinking during read is very much faster than decompressing the whole
+image and then shrinking. Example:
+
+  fred.jpg:8
+
+will return fred.jpg shrink by a factor of 8.
 
 Any embedded ICC profiles are ignored: you always just get the RGB from the
 file. Instead, the embedded profile will be attached to the image as metadata.