diff --git a/third_party/libtiff/0039-handling-of-tifftag-inknames.patch b/third_party/libtiff/0039-handling-of-tifftag-inknames.patch
new file mode 100644
index 0000000..5ffd695
--- /dev/null
+++ b/third_party/libtiff/0039-handling-of-tifftag-inknames.patch
@@ -0,0 +1,192 @@
+diff --git a/third_party/libtiff/tif_dir.c b/third_party/libtiff/tif_dir.c
+index 347b7115c..ac7097c22 100644
+--- a/third_party/libtiff/tif_dir.c
++++ b/third_party/libtiff/tif_dir.c
+@@ -138,32 +138,30 @@ setExtraSamples(TIFF* tif, va_list ap, uint32* v)
+ }
+ 
+ /*
+- * Confirm we have "samplesperpixel" ink names separated by \0.  Returns 
++ * Count ink names separated by \0.  Returns
+  * zero if the ink names are not as expected.
+  */
+-static uint32
+-checkInkNamesString(TIFF* tif, uint32 slen, const char* s)
++static uint16
++countInkNamesString(TIFF *tif, uint32 slen, const char *s)
+ {
+-	TIFFDirectory* td = &tif->tif_dir;
+-	uint16 i = td->td_samplesperpixel;
++	uint16 i = 0;
++	const char *ep = s + slen;
++	const char *cp = s;
+ 
+ 	if (slen > 0) {
+-		const char* ep = s+slen;
+-		const char* cp = s;
+-		for (; i > 0; i--) {
++		do {
+ 			for (; cp < ep && *cp != '\0'; cp++) {}
+ 			if (cp >= ep)
+ 				goto bad;
+ 			cp++;				/* skip \0 */
+-		}
+-		return ((uint32)(cp-s));
++			i++;
++		} while (cp < ep);
++		return (i);
+ 	}
+ bad:
+ 	TIFFErrorExt(tif->tif_clientdata, "TIFFSetField",
+-	    "%s: Invalid InkNames value; expecting %d names, found %d",
+-	    tif->tif_name,
+-	    td->td_samplesperpixel,
+-	    td->td_samplesperpixel-i);
++		"%s: Invalid InkNames value; no NUL at given buffer end location %u, after %u ink",
++		tif->tif_name, slen, i);
+ 	return (0);
+ }
+ 
+@@ -477,13 +475,61 @@ _TIFFVSetField(TIFF* tif, uint32 tag, va_list ap)
+ 		_TIFFsetFloatArray(&td->td_refblackwhite, va_arg(ap, float*), 6);
+ 		break;
+ 	case TIFFTAG_INKNAMES:
+-		v = (uint16) va_arg(ap, uint16_vap);
+-		s = va_arg(ap, char*);
+-		v = checkInkNamesString(tif, v, s);
+-		status = v > 0;
+-		if( v > 0 ) {
+-			_TIFFsetNString(&td->td_inknames, s, v);
+-			td->td_inknameslen = v;
++		{
++			v = (uint16) va_arg(ap, uint16_vap);
++			s = va_arg(ap, char*);
++			uint16 ninksinstring;
++			ninksinstring = countInkNamesString(tif, v, s);
++			status = ninksinstring > 0;
++			if(ninksinstring > 0 ) {
++				_TIFFsetNString(&td->td_inknames, s, v);
++				td->td_inknameslen = v;
++				/* Set NumberOfInks to the value ninksinstring */
++				if (TIFFFieldSet(tif, FIELD_NUMBEROFINKS))
++				{
++					if (td->td_numberofinks != ninksinstring) {
++						TIFFErrorExt(tif->tif_clientdata, module,
++							"Warning %s; Tag %s:\n  Value %u of NumberOfInks is different from the number of inks %u.\n  -> NumberOfInks value adapted to %u",
++							tif->tif_name, fip->field_name, td->td_numberofinks, ninksinstring, ninksinstring);
++						td->td_numberofinks = ninksinstring;
++					}
++				} else {
++					td->td_numberofinks = ninksinstring;
++					TIFFSetFieldBit(tif, FIELD_NUMBEROFINKS);
++				}
++				if (TIFFFieldSet(tif, FIELD_SAMPLESPERPIXEL))
++				{
++					if (td->td_numberofinks != td->td_samplesperpixel) {
++						TIFFErrorExt(tif->tif_clientdata, module,
++							"Warning %s; Tag %s:\n  Value %u of NumberOfInks is different from the SamplesPerPixel value %u",
++							tif->tif_name, fip->field_name, td->td_numberofinks, td->td_samplesperpixel);
++					}
++				}
++			}
++		}
++		break;
++	case TIFFTAG_NUMBEROFINKS:
++		v = (uint16)va_arg(ap, uint16_vap);
++		/* If InkNames already set also NumberOfInks is set accordingly and should be equal */
++		if (TIFFFieldSet(tif, FIELD_INKNAMES))
++		{
++			if (v != td->td_numberofinks) {
++				TIFFErrorExt(tif->tif_clientdata, module,
++					"Error %s; Tag %s:\n  It is not possible to set the value %u for NumberOfInks\n  which is different from the number of inks in the InkNames tag (%u)",
++					tif->tif_name, fip->field_name, v, td->td_numberofinks);
++				/* Do not set / overwrite number of inks already set by InkNames case accordingly. */
++				status = 0;
++			}
++		} else {
++			td->td_numberofinks = (uint16)v;
++			if (TIFFFieldSet(tif, FIELD_SAMPLESPERPIXEL))
++			{
++				if (td->td_numberofinks != td->td_samplesperpixel) {
++					TIFFErrorExt(tif->tif_clientdata, module,
++						"Warning %s; Tag %s:\n  Value %u of NumberOfInks is different from the SamplesPerPixel value %u",
++						tif->tif_name, fip->field_name, v, td->td_samplesperpixel);
++				}
++			}
+ 		}
+ 		break;
+ 	case TIFFTAG_PERSAMPLE:
+@@ -1114,6 +1160,9 @@ _TIFFVGetField(TIFF* tif, uint32 tag, va_list ap)
+ 		case TIFFTAG_INKNAMES:
+ 			*va_arg(ap, const char**) = td->td_inknames;
+ 			break;
++		case TIFFTAG_NUMBEROFINKS:
++			*va_arg(ap, uint16_t *) = td->td_numberofinks;
++			break;
+ 		default:
+ 			{
+ 				int i;
+diff --git a/third_party/libtiff/tif_dir.h b/third_party/libtiff/tif_dir.h
+index f608dd713..399a35ab3 100644
+--- a/third_party/libtiff/tif_dir.h
++++ b/third_party/libtiff/tif_dir.h
+@@ -117,6 +117,7 @@ typedef struct {
+ 	/* CMYK parameters */
+ 	int     td_inknameslen;
+ 	char*   td_inknames;
++	uint16_t td_numberofinks;                 /* number of inks in InkNames string */
+ 
+ 	int     td_customValueCount;
+         TIFFTagValue *td_customValues;
+@@ -174,6 +175,7 @@ typedef struct {
+ #define FIELD_TRANSFERFUNCTION         44
+ #define FIELD_INKNAMES                 46
+ #define FIELD_SUBIFD                   49
++#define FIELD_NUMBEROFINKS             50
+ /*      FIELD_CUSTOM (see tiffio.h)    65 */
+ /* end of support for well-known tags; codec-private tags follow */
+ #define FIELD_CODEC                    66  /* base of codec-private tags */
+diff --git a/third_party/libtiff/tif_dirinfo.c b/third_party/libtiff/tif_dirinfo.c
+index 7217042c2..ea3b0c20f 100644
+--- a/third_party/libtiff/tif_dirinfo.c
++++ b/third_party/libtiff/tif_dirinfo.c
+@@ -114,7 +114,7 @@ tiffFields[] = {
+ 	{ TIFFTAG_SUBIFD, -1, -1, TIFF_IFD8, 0, TIFF_SETGET_C16_IFD8, TIFF_SETGET_UNDEFINED, FIELD_SUBIFD, 1, 1, "SubIFD", (TIFFFieldArray*) &tiffFieldArray },
+ 	{ TIFFTAG_INKSET, 1, 1, TIFF_SHORT, 0, TIFF_SETGET_UINT16, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 0, 0, "InkSet", NULL },
+ 	{ TIFFTAG_INKNAMES, -1, -1, TIFF_ASCII, 0, TIFF_SETGET_C16_ASCII, TIFF_SETGET_UNDEFINED, FIELD_INKNAMES, 1, 1, "InkNames", NULL },
+-	{ TIFFTAG_NUMBEROFINKS, 1, 1, TIFF_SHORT, 0, TIFF_SETGET_UINT16, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 1, 0, "NumberOfInks", NULL },
++	{ TIFFTAG_NUMBEROFINKS, 1, 1, TIFF_SHORT, 0, TIFF_SETGET_UINT16, TIFF_SETGET_UNDEFINED, FIELD_NUMBEROFINKS, 1, 0, "NumberOfInks", NULL },
+ 	{ TIFFTAG_DOTRANGE, 2, 2, TIFF_SHORT, 0, TIFF_SETGET_UINT16_PAIR, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 0, 0, "DotRange", NULL },
+ 	{ TIFFTAG_TARGETPRINTER, -1, -1, TIFF_ASCII, 0, TIFF_SETGET_ASCII, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 1, 0, "TargetPrinter", NULL },
+ 	{ TIFFTAG_EXTRASAMPLES, -1, -1, TIFF_SHORT, 0, TIFF_SETGET_C16_UINT16, TIFF_SETGET_UNDEFINED, FIELD_EXTRASAMPLES, 0, 1, "ExtraSamples", NULL },
+diff --git a/third_party/libtiff/tif_dirwrite.c b/third_party/libtiff/tif_dirwrite.c
+index f481250e3..fe6d6558a 100644
+--- a/third_party/libtiff/tif_dirwrite.c
++++ b/third_party/libtiff/tif_dirwrite.c
+@@ -692,6 +692,11 @@ TIFFWriteDirectorySec(TIFF* tif, int isimage, int imagedone, uint64* pdiroff)
+ 				if (!TIFFWriteDirectoryTagAscii(tif,&ndir,dir,TIFFTAG_INKNAMES,tif->tif_dir.td_inknameslen,tif->tif_dir.td_inknames))
+ 					goto bad;
+ 			}
++			if (TIFFFieldSet(tif, FIELD_NUMBEROFINKS))
++			{
++				if (!TIFFWriteDirectoryTagShort(tif, &ndir, dir, TIFFTAG_NUMBEROFINKS, tif->tif_dir.td_numberofinks))
++					goto bad;
++			}
+ 			if (TIFFFieldSet(tif,FIELD_SUBIFD))
+ 			{
+ 				if (!TIFFWriteDirectoryTagSubifd(tif,&ndir,dir))
+diff --git a/third_party/libtiff/tif_print.c b/third_party/libtiff/tif_print.c
+index a0737941f..a9f05a7ec 100644
+--- a/third_party/libtiff/tif_print.c
++++ b/third_party/libtiff/tif_print.c
+@@ -402,6 +402,10 @@ TIFFPrintDirectory(TIFF* tif, FILE* fd, long flags)
+ 		}
+                 fputs("\n", fd);
+ 	}
++	if (TIFFFieldSet(tif, FIELD_NUMBEROFINKS)) {
++		fprintf(fd, "  NumberOfInks: %d\n",
++			td->td_numberofinks);
++	}
+ 	if (TIFFFieldSet(tif,FIELD_THRESHHOLDING)) {
+ 		fprintf(fd, "  Thresholding: ");
+ 		switch (td->td_threshholding) {
diff --git a/third_party/libtiff/README.pdfium b/third_party/libtiff/README.pdfium
index 08bbe37..11547b7 100644
--- a/third_party/libtiff/README.pdfium
+++ b/third_party/libtiff/README.pdfium
@@ -22,3 +22,4 @@
 0036-Replace-sprintf-calls-with-snprintf.patch: Replace sprintf with snprintf for macOS 13 SDK compatibility, from https://gitlab.com/libtiff/libtiff/-/merge_requests/408, edited to apply to PDFium, which does not have libtiff 352cb5a4fb11.
 0037-tiff-read-rgba-tile-ext.patch: Fix (unsigned) integer overflow on strips/tiles > 2 GB.
 0038-fix-ojpeg-hack.patch: Fix OJPEG hack.
+0039-handling-of-tifftag-inknames.patch: Revised handling of TIFFTAG_INKNAMES and related TIFFTAG_NUMBEROFINKS value.
diff --git a/third_party/libtiff/tif_dir.c b/third_party/libtiff/tif_dir.c
index 347b711..ac7097c 100644
--- a/third_party/libtiff/tif_dir.c
+++ b/third_party/libtiff/tif_dir.c
@@ -138,32 +138,30 @@
 }
 
 /*
- * Confirm we have "samplesperpixel" ink names separated by \0.  Returns 
+ * Count ink names separated by \0.  Returns
  * zero if the ink names are not as expected.
  */
-static uint32
-checkInkNamesString(TIFF* tif, uint32 slen, const char* s)
+static uint16
+countInkNamesString(TIFF *tif, uint32 slen, const char *s)
 {
-	TIFFDirectory* td = &tif->tif_dir;
-	uint16 i = td->td_samplesperpixel;
+	uint16 i = 0;
+	const char *ep = s + slen;
+	const char *cp = s;
 
 	if (slen > 0) {
-		const char* ep = s+slen;
-		const char* cp = s;
-		for (; i > 0; i--) {
+		do {
 			for (; cp < ep && *cp != '\0'; cp++) {}
 			if (cp >= ep)
 				goto bad;
 			cp++;				/* skip \0 */
-		}
-		return ((uint32)(cp-s));
+			i++;
+		} while (cp < ep);
+		return (i);
 	}
 bad:
 	TIFFErrorExt(tif->tif_clientdata, "TIFFSetField",
-	    "%s: Invalid InkNames value; expecting %d names, found %d",
-	    tif->tif_name,
-	    td->td_samplesperpixel,
-	    td->td_samplesperpixel-i);
+		"%s: Invalid InkNames value; no NUL at given buffer end location %u, after %u ink",
+		tif->tif_name, slen, i);
 	return (0);
 }
 
@@ -477,13 +475,61 @@
 		_TIFFsetFloatArray(&td->td_refblackwhite, va_arg(ap, float*), 6);
 		break;
 	case TIFFTAG_INKNAMES:
-		v = (uint16) va_arg(ap, uint16_vap);
-		s = va_arg(ap, char*);
-		v = checkInkNamesString(tif, v, s);
-		status = v > 0;
-		if( v > 0 ) {
-			_TIFFsetNString(&td->td_inknames, s, v);
-			td->td_inknameslen = v;
+		{
+			v = (uint16) va_arg(ap, uint16_vap);
+			s = va_arg(ap, char*);
+			uint16 ninksinstring;
+			ninksinstring = countInkNamesString(tif, v, s);
+			status = ninksinstring > 0;
+			if(ninksinstring > 0 ) {
+				_TIFFsetNString(&td->td_inknames, s, v);
+				td->td_inknameslen = v;
+				/* Set NumberOfInks to the value ninksinstring */
+				if (TIFFFieldSet(tif, FIELD_NUMBEROFINKS))
+				{
+					if (td->td_numberofinks != ninksinstring) {
+						TIFFErrorExt(tif->tif_clientdata, module,
+							"Warning %s; Tag %s:\n  Value %u of NumberOfInks is different from the number of inks %u.\n  -> NumberOfInks value adapted to %u",
+							tif->tif_name, fip->field_name, td->td_numberofinks, ninksinstring, ninksinstring);
+						td->td_numberofinks = ninksinstring;
+					}
+				} else {
+					td->td_numberofinks = ninksinstring;
+					TIFFSetFieldBit(tif, FIELD_NUMBEROFINKS);
+				}
+				if (TIFFFieldSet(tif, FIELD_SAMPLESPERPIXEL))
+				{
+					if (td->td_numberofinks != td->td_samplesperpixel) {
+						TIFFErrorExt(tif->tif_clientdata, module,
+							"Warning %s; Tag %s:\n  Value %u of NumberOfInks is different from the SamplesPerPixel value %u",
+							tif->tif_name, fip->field_name, td->td_numberofinks, td->td_samplesperpixel);
+					}
+				}
+			}
+		}
+		break;
+	case TIFFTAG_NUMBEROFINKS:
+		v = (uint16)va_arg(ap, uint16_vap);
+		/* If InkNames already set also NumberOfInks is set accordingly and should be equal */
+		if (TIFFFieldSet(tif, FIELD_INKNAMES))
+		{
+			if (v != td->td_numberofinks) {
+				TIFFErrorExt(tif->tif_clientdata, module,
+					"Error %s; Tag %s:\n  It is not possible to set the value %u for NumberOfInks\n  which is different from the number of inks in the InkNames tag (%u)",
+					tif->tif_name, fip->field_name, v, td->td_numberofinks);
+				/* Do not set / overwrite number of inks already set by InkNames case accordingly. */
+				status = 0;
+			}
+		} else {
+			td->td_numberofinks = (uint16)v;
+			if (TIFFFieldSet(tif, FIELD_SAMPLESPERPIXEL))
+			{
+				if (td->td_numberofinks != td->td_samplesperpixel) {
+					TIFFErrorExt(tif->tif_clientdata, module,
+						"Warning %s; Tag %s:\n  Value %u of NumberOfInks is different from the SamplesPerPixel value %u",
+						tif->tif_name, fip->field_name, v, td->td_samplesperpixel);
+				}
+			}
 		}
 		break;
 	case TIFFTAG_PERSAMPLE:
@@ -1114,6 +1160,9 @@
 		case TIFFTAG_INKNAMES:
 			*va_arg(ap, const char**) = td->td_inknames;
 			break;
+		case TIFFTAG_NUMBEROFINKS:
+			*va_arg(ap, uint16_t *) = td->td_numberofinks;
+			break;
 		default:
 			{
 				int i;
diff --git a/third_party/libtiff/tif_dir.h b/third_party/libtiff/tif_dir.h
index f608dd7..399a35a 100644
--- a/third_party/libtiff/tif_dir.h
+++ b/third_party/libtiff/tif_dir.h
@@ -117,6 +117,7 @@
 	/* CMYK parameters */
 	int     td_inknameslen;
 	char*   td_inknames;
+	uint16_t td_numberofinks;                 /* number of inks in InkNames string */
 
 	int     td_customValueCount;
         TIFFTagValue *td_customValues;
@@ -174,6 +175,7 @@
 #define FIELD_TRANSFERFUNCTION         44
 #define FIELD_INKNAMES                 46
 #define FIELD_SUBIFD                   49
+#define FIELD_NUMBEROFINKS             50
 /*      FIELD_CUSTOM (see tiffio.h)    65 */
 /* end of support for well-known tags; codec-private tags follow */
 #define FIELD_CODEC                    66  /* base of codec-private tags */
diff --git a/third_party/libtiff/tif_dirinfo.c b/third_party/libtiff/tif_dirinfo.c
index 7217042..ea3b0c2 100644
--- a/third_party/libtiff/tif_dirinfo.c
+++ b/third_party/libtiff/tif_dirinfo.c
@@ -114,7 +114,7 @@
 	{ TIFFTAG_SUBIFD, -1, -1, TIFF_IFD8, 0, TIFF_SETGET_C16_IFD8, TIFF_SETGET_UNDEFINED, FIELD_SUBIFD, 1, 1, "SubIFD", (TIFFFieldArray*) &tiffFieldArray },
 	{ TIFFTAG_INKSET, 1, 1, TIFF_SHORT, 0, TIFF_SETGET_UINT16, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 0, 0, "InkSet", NULL },
 	{ TIFFTAG_INKNAMES, -1, -1, TIFF_ASCII, 0, TIFF_SETGET_C16_ASCII, TIFF_SETGET_UNDEFINED, FIELD_INKNAMES, 1, 1, "InkNames", NULL },
-	{ TIFFTAG_NUMBEROFINKS, 1, 1, TIFF_SHORT, 0, TIFF_SETGET_UINT16, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 1, 0, "NumberOfInks", NULL },
+	{ TIFFTAG_NUMBEROFINKS, 1, 1, TIFF_SHORT, 0, TIFF_SETGET_UINT16, TIFF_SETGET_UNDEFINED, FIELD_NUMBEROFINKS, 1, 0, "NumberOfInks", NULL },
 	{ TIFFTAG_DOTRANGE, 2, 2, TIFF_SHORT, 0, TIFF_SETGET_UINT16_PAIR, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 0, 0, "DotRange", NULL },
 	{ TIFFTAG_TARGETPRINTER, -1, -1, TIFF_ASCII, 0, TIFF_SETGET_ASCII, TIFF_SETGET_UNDEFINED, FIELD_CUSTOM, 1, 0, "TargetPrinter", NULL },
 	{ TIFFTAG_EXTRASAMPLES, -1, -1, TIFF_SHORT, 0, TIFF_SETGET_C16_UINT16, TIFF_SETGET_UNDEFINED, FIELD_EXTRASAMPLES, 0, 1, "ExtraSamples", NULL },
diff --git a/third_party/libtiff/tif_dirwrite.c b/third_party/libtiff/tif_dirwrite.c
index f481250..fe6d655 100644
--- a/third_party/libtiff/tif_dirwrite.c
+++ b/third_party/libtiff/tif_dirwrite.c
@@ -692,6 +692,11 @@
 				if (!TIFFWriteDirectoryTagAscii(tif,&ndir,dir,TIFFTAG_INKNAMES,tif->tif_dir.td_inknameslen,tif->tif_dir.td_inknames))
 					goto bad;
 			}
+			if (TIFFFieldSet(tif, FIELD_NUMBEROFINKS))
+			{
+				if (!TIFFWriteDirectoryTagShort(tif, &ndir, dir, TIFFTAG_NUMBEROFINKS, tif->tif_dir.td_numberofinks))
+					goto bad;
+			}
 			if (TIFFFieldSet(tif,FIELD_SUBIFD))
 			{
 				if (!TIFFWriteDirectoryTagSubifd(tif,&ndir,dir))
diff --git a/third_party/libtiff/tif_print.c b/third_party/libtiff/tif_print.c
index a073794..a9f05a7 100644
--- a/third_party/libtiff/tif_print.c
+++ b/third_party/libtiff/tif_print.c
@@ -402,6 +402,10 @@
 		}
                 fputs("\n", fd);
 	}
+	if (TIFFFieldSet(tif, FIELD_NUMBEROFINKS)) {
+		fprintf(fd, "  NumberOfInks: %d\n",
+			td->td_numberofinks);
+	}
 	if (TIFFFieldSet(tif,FIELD_THRESHHOLDING)) {
 		fprintf(fd, "  Thresholding: ");
 		switch (td->td_threshholding) {