From 676e803e4c34aa223da0b811c8a3ef11ed801afb Mon Sep 17 00:00:00 2001
From: Marti Maria <marti.maria@littlecms.com>
Date: Sun, 10 Nov 2024 19:58:35 +0100
Subject: [PATCH] Fix a bug on CMYK gamut check when using float Lab as input
 space.

For what it seems, it has been there for many years.
---
 src/cmsgmt.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/cmsgmt.c b/src/cmsgmt.c
index 7067cf11..3064c166 100644
--- a/src/cmsgmt.c
+++ b/src/cmsgmt.c
@@ -298,8 +298,9 @@ cmsPipeline* _cmsCreateGamutCheckPipeline(cmsContext ContextID,
     cmsUInt32Number dwFormat;
     GAMUTCHAIN Chain;
     cmsUInt32Number nGridpoints;
-    cmsInt32Number nChannels;
+    cmsInt32Number nChannels, nInputChannels;
     cmsColorSpaceSignature ColorSpace;
+    cmsColorSpaceSignature InputColorSpace;
     cmsUInt32Number i;
     cmsHPROFILE ProfileList[256];
     cmsBool     BPCList[256];
@@ -345,11 +346,13 @@ cmsPipeline* _cmsCreateGamutCheckPipeline(cmsContext ContextID,
     AdaptationList[nGamutPCSposition] = 1.0;
     IntentList[nGamutPCSposition] = INTENT_RELATIVE_COLORIMETRIC;
 
-
     ColorSpace  = cmsGetColorSpace(hGamut);
     nChannels   = cmsChannelsOfColorSpace(ColorSpace);
     nGridpoints = _cmsReasonableGridpointsByColorspace(ColorSpace, cmsFLAGS_HIGHRESPRECALC);
-    dwFormat    = (CHANNELS_SH(nChannels)|BYTES_SH(2));
+    
+    InputColorSpace = cmsGetColorSpace(ProfileList[0]);
+    nInputChannels  = cmsChannelsOfColorSpace(InputColorSpace);
+    dwFormat        = (CHANNELS_SH(nInputChannels)|BYTES_SH(2));
 
     // 16 bits to Lab double
     Chain.hInput = cmsCreateExtendedTransform(ContextID,