From 6df26bfc9b818b44354d6d916df7d79f65d26788 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Angel=20S=C3=A1nchez?= <angelsanchez@inedit.com>
Date: Thu, 25 Jul 2019 10:40:52 +0200
Subject: [PATCH] load lab 8bit with alpha to labS

---
 libvips/foreign/tiff2vips.c | 62 +++++++++++++++++++++++++++++++++++--
 libvips/foreign/vips2tiff.c | 41 ++++++++++++------------
 2 files changed, 81 insertions(+), 22 deletions(-)

diff --git a/libvips/foreign/tiff2vips.c b/libvips/foreign/tiff2vips.c
index 245f9807..9482f22c 100644
--- a/libvips/foreign/tiff2vips.c
+++ b/libvips/foreign/tiff2vips.c
@@ -787,6 +787,57 @@ rtiff_parse_labpack( Rtiff *rtiff, VipsImage *out )
 	return( 0 );
 }
 
+
+/* Per-scanline process function for 8-bit VIPS_CODING_LAB to 16-bit LabS with
+ * alpha.
+ */
+static void
+rtiff_lab_with_alpha_line( Rtiff *rtiff,
+	VipsPel *q, VipsPel *p, int n, void *dummy )
+{
+	int samples_per_pixel = rtiff->header.samples_per_pixel;
+
+	unsigned char *p1;
+	short *q1;
+	int x;
+
+	p1 = (unsigned char *) p;
+	q1 = (short *) q;
+	for( x = 0; x < n; x++ ) {
+		int i;
+
+		q1[0] = ((unsigned int) p1[0]) * 32767 / 255;
+		q1[1] = ((short) p1[1]) << 8;
+		q1[2] = ((short) p1[2]) << 8;
+
+		for( i = 3; i < samples_per_pixel; i++ )
+			q1[i] = (p1[i] << 8) + p1[i];
+
+		q1 += samples_per_pixel;
+		p1 += samples_per_pixel;
+	}
+}
+
+/* Read an 8-bit LAB image with alpha bands into 16-bit LabS.
+ */
+static int
+rtiff_parse_lab_with_alpha( Rtiff *rtiff, VipsImage *out )
+{
+	if( rtiff_check_min_samples( rtiff, 4 ) ||
+		rtiff_check_bits( rtiff, 8 ) ||
+		rtiff_check_interpretation( rtiff, PHOTOMETRIC_CIELAB ) )
+		return( -1 );
+
+	out->Bands = rtiff->header.samples_per_pixel;
+	out->BandFmt = VIPS_FORMAT_SHORT;
+	out->Coding = VIPS_CODING_NONE;
+	out->Type = VIPS_INTERPRETATION_LABS;
+
+	rtiff->sfn = rtiff_lab_with_alpha_line;
+
+	return( 0 );
+}
+
 /* Per-scanline process function for LABS.
  */
 static void
@@ -802,7 +853,7 @@ rtiff_labs_line( Rtiff *rtiff, VipsPel *q, VipsPel *p, int n, void *dummy )
 	p1 = (unsigned short *) p;
 	q1 = (short *) q;
 	for( x = 0; x < n; x++ ) {
-		/* We use a signed int16 for L.
+		/* We use signed int16 for L.
 		 */
 		q1[0] = p1[0] >> 1;
 
@@ -1314,10 +1365,15 @@ rtiff_pick_reader( Rtiff *rtiff )
 	int bits_per_sample = rtiff->header.bits_per_sample;
 	int photometric_interpretation = 
 		rtiff->header.photometric_interpretation;
+	int samples_per_pixel = rtiff->header.samples_per_pixel;
 
 	if( photometric_interpretation == PHOTOMETRIC_CIELAB ) {
-		if( bits_per_sample == 8 )
-			return( rtiff_parse_labpack );
+		if( bits_per_sample == 8 ) {
+			if( samples_per_pixel > 3 )
+				return( rtiff_parse_lab_with_alpha );
+			else
+				return( rtiff_parse_labpack );
+		}
 		if( bits_per_sample == 16 )
 			return( rtiff_parse_labs );
 	}
diff --git a/libvips/foreign/vips2tiff.c b/libvips/foreign/vips2tiff.c
index fca3d64e..ed534d50 100644
--- a/libvips/foreign/vips2tiff.c
+++ b/libvips/foreign/vips2tiff.c
@@ -1117,18 +1117,18 @@ wtiff_new( VipsImage *im, const char *filename,
 static void
 LabQ2LabC( VipsPel *q, VipsPel *p, int n )
 {
-        int x;
+	int x;
 
-        for( x = 0; x < n; x++ ) {
-                /* Get most significant 8 bits of lab.
-                 */
-                q[0] = p[0];
-                q[1] = p[1];
-                q[2] = p[2];
+	for( x = 0; x < n; x++ ) {
+		/* Get most significant 8 bits of lab.
+		 */
+		q[0] = p[0];
+		q[1] = p[1];
+		q[2] = p[2];
 
-                p += 4;
-                q += 3;
-        }
+		p += 4;
+		q += 3;
+	}
 }
 
 /* Pack 8 bit VIPS to 1 bit TIFF.
@@ -1236,22 +1236,25 @@ invert_band0( Wtiff *wtiff, VipsPel *q, VipsPel *p, int n )
 /* Convert VIPS LABS to TIFF 16 bit LAB.
  */
 static void
-LabS2Lab16( VipsPel *q, VipsPel *p, int n )
+LabS2Lab16( VipsPel *q, VipsPel *p, int n, int samples_per_pixel )
 {
-        int x;
+	int x;
 	short *p1 = (short *) p;
 	unsigned short *q1 = (unsigned short *) q;
 
         for( x = 0; x < n; x++ ) {
+		int i;
+
                 /* TIFF uses unsigned 16 bit ... move zero, scale up L.
                  */
                 q1[0] = VIPS_LSHIFT_INT( (int) p1[0], 1 );
-                q1[1] = p1[1];
-                q1[2] = p1[2];
 
-                p1 += 3;
-                q1 += 3;
-        }
+		for( i = 1; i < samples_per_pixel; i++ )
+			q1[i] = p1[i];
+
+		q1 += samples_per_pixel;
+		p1 += samples_per_pixel;
+    }
 }
 
 /* Pack the pixels in @area from @in into a TIFF tile buffer.
@@ -1286,7 +1289,7 @@ wtiff_pack2tiff( Wtiff *wtiff, Layer *layer,
 			invert_band0( wtiff, q, p, area->width );
 		else if( wtiff->im->BandFmt == VIPS_FORMAT_SHORT &&
 			wtiff->im->Type == VIPS_INTERPRETATION_LABS )
-			LabS2Lab16( q, p, area->width );
+			LabS2Lab16( q, p, area->width, in->im->Bands );
 		else
 			memcpy( q, p, 
 				area->width * 
@@ -1369,7 +1372,7 @@ wtiff_layer_write_strip( Wtiff *wtiff, Layer *layer, VipsRegion *strip )
 		}
 		else if( im->BandFmt == VIPS_FORMAT_SHORT &&
 			im->Type == VIPS_INTERPRETATION_LABS ) {
-			LabS2Lab16( wtiff->tbuf, p, im->Xsize );
+			LabS2Lab16( wtiff->tbuf, p, im->Xsize, im->Bands );
 			p = wtiff->tbuf;
 		}
 		else if( wtiff->onebit ) {